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DCS Computer Hardware Digital to Digital Converter User's Manual

1. s seneenssnnsnnenesnrnneennnnnnne 22 28 RTR E 71 105 DSD data algonment 80 DSD filter options ec eeccceeeeeeeeeeeeeeeees 71 DSD filters 200 eceececeeeeeeceeeseeaeeeees 97 98 DSD full scale 0 0 0 eeceeeeeeeeeeeeeees 71 98 DSD modulators 71 DSD Output MOE cee ceecceeeeeeeeeeeeeeeees 45 DSD outputs FC 15 DSD outputs GC 17 DSD Quad input selechng cee 12 DSD Quad output connecting 0 0000000n 18 DSD SDIF input selecting c ee 12 DSD SDIF output Conpechng 18 DODO DSE EE 42 DSD DCremoval 0 eeeececeeeeeeeeeeeeees 45 DSD level meierng 40 57 59 DSD SDIF input cc eeccceeeeeeeeeeeeeeeeees 66 DSD SDIF interface ceecceeeeeeeeeeeees 86 DSD SDIF Out ul ccsccdceccedeeaccseicccsseesceacdarsinnes 67 Dual AES input selecting a0nnnannannnannaaanne 12 Dual AES output mode ees 45 Dual AES outputs connecting 000000000 18 Dual AES outputs FC 15 Dual AES outputs GC 17 dCS 974 User Manual dCS Ltd Dual AES to single wire 23 E CI DUON BEEN 61 68 editing a store name 61 Enter DUM OM NEE 62 68 enor MOM WEEN 52 Error Monitor men 39 52 error reported by destination device 120 ol AO I f cee er 52 F FURS et Aere eege 13 FUME TINCT DEER 45 TIO ODUOINS Ee eegene 45 filter options DS T1 filter responses DCH 99 filter tte Getpeieeierager eebe een 45 mter CULO MM EEN 73 filter energy emmeagt 45 PUES R ot edso
2. This menu turns on bit activity monitors on the selected input signal for use on the audio data it can find out how many active bits you have coming in or identify stuck bits in other equipment This only works for PCM inputs the entry disappears for DSD inputs This feature does NOT monitor the units outputs Level Meters Controls level metering of the output data The level meters may be used to monitor DSD signals by setting a DSD to PCM conversion Even though the conversion may not be used the level metering will effectively meter the DSD input Display Controls the Brightness Contrast Cursor direction and Backlight timeout behaviour of the display dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 Sample Rate Conversion Format Conversion Submenu Audio Input Select Sync Source The Sample Rate Conversion menu is as follows SamF le Rate Conversion koudio Input Select Sync Source Multirle Channel Syne Input Gang le Rate OuULFUL Sample Rate Quteut Mode Filter Select the required input from the list and press Set The Dua AES option requires that the Inout Sample Rate be set to 192 kS s 176 4 kS s 96 kS s or 88 2 kS s The Quad AES option requires that the Inout Sample Rate be set to 192 kS s or 176 4 kS s The DSD setting automatically identifies DSD SDIF 2 or DSD SDIF 3 data on the DSD SDIF input select a source to synchronise to from the list and press Set The ava
3. e Check that the destination device can receive the sample rate the dCS 974 is putting out in the appropriate 1 wire 2 wire 4 wire format Output audio quality is poor e Check that Output Wordlength is set correctly e f truncating from 24 bits use Noise Shaping and or Dither e Ensure the unit is locked to the source device or an external clock driving the source device e Converting from a very low sampling rate to a high sampling rate cannot give sparkling hi fi performance although it can improve things a bit the upsampling phenomenon The dCS 974 can convert a 12 kS s 8 bit signal up to 192 kS s 24 bit in real time but the linearity will be poor due to lack of source information the noise floor will be high and the audio bandwidth will still be 5kHz i e not much better than a telephone line dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Output audio bandwidth is low e During sample rate conversion the signal is digitally filtered this is essential for good performance The output audio bandwidth will usually be slightly less than half the lowest sample frequency involved in the conversion A stereo output signal is expected but signal is present on one channel only e Check that Balance is not set to one side e If PCM SDIF 2 or DSD SDIF 2 is used check that CH1 OUT and CH2 OUT are both connected e Check you are not using a Dual AES mode with just one cable connected A
4. 1 0x dCS Ltd May 2001 Manual part no DOC1241121A1 Page 65 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 THE HARDWARE CONTROLS AND CONNECTORS Rear Panel NCE LOOP REFERE D IN OUT AES CLK OUT SYNC INPUT AES EBU OUTPUTS Figure 17 Rear Panel All input and output connectors are mounted on the rear panel Individual connectors are identified by the panel legend Signal Inputs AES EBU Digital Inputs 3 pin XLR Female 4 off AES 1 AES 4 Used for AES3 format signals AES 1 and AES 2 are used together in Dual AES mode All four inputs are used together for Quad AES or DSD Quad modes AES EBU Reference Loop 3 pin XLR Female Male AES Ref Loop IN amp OUT Loop IN is used for AES3 references and also for Sync Link operation in multi channel synchronising Loop OUT is hard wired to Loop IN allowing the reference to be daisy chained through several units Sync Input BNC This is intended for future enhancements SPDIF Inputs Various 3 off RCA IN BNC IN TOS IN Used for SPDIF inputs Pull the plastic dust cover out of the TOS input before use DSD SDIF Input BNC 4 off CH1 IN CH2 IN WCLK IN LOOP OUT The upper group of four DSD SDIF connectors form an input interface They are used as a set for
5. 1 pass DSD 2 pass 2 pass 2 pass 2 pass 2 pass 2 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass Table 2 One Pass and Two Pass Conversions If the input sample rate were 32 kS s then the display would offer a different selection OnVers LOF 1d Quteut Rate a d List mm e d Me Ah Ah DU mn ir Lu Luut rt The input sample rate can be changed to one that is incompatible with the currently selected Output Sample Rate because it needs a 2 pass operation As an example we might have 11 025 kS s coming in not on Auto and try to select 96 kS s The dCS 974 will detect that this ought to be a 2 pass operation and display the following information box 44 4 CER ch Invalid Fs In for Fs Out Press a key to alter Fs Out Bali L dB RF db While displaying this information box the output of the dCS 974 will be muted To continue either Change the Inout Sample Rate to one suitable for conversion see the table above or Press any key and the dCS 974 will display a list of valid Output Sample Rates as follows for our 11 025 kS s example dCS 974 User Manual dCs Ltd Output Mode Filter Manual for Software Version 1 0x May 2001 l2k 5 5 11 625k 5 5 For a 2 Pass conversion convert the input to an intermediate sample rate and either feed it direct into another dCS 974 or record the result then convert from the intermediate sample rate to the required sample rate You can always choose on
6. 192kS s or Quad AES at 176 4 or 192kS s AES EBU REFERENCE LOOP A OUT a Q Oll RCA G Be DSD SDIF O DSD Quad DSD SDIF 2 or DSD SDIF 3 Figure 10 PCM to DSD conversion The dCS 974 converts PCM to DSD including 176 4 kS s to DSD using the arrangement given below Connect any digital audio source of any wordlength between 8 and 24 bits using single Dual or Quad AES to the AES inputs or using single or double speed SDIF 2 to the SDIF 2 inputs or using single wire SPDIF to the appropriate SPDIF input and select the input accordingly Set Output Mode to DSD SDIF 2 or DSD SDIF 3 Choose a Filter if you wish Output SDIF 2 via the DSD SDIF connectors two data cables and one word clock or SDIF 3 with just two data cables Alternatively take the DSD Quad output from the AES 1 2 3 and 4 outputs Sample Rate Conversion settings Sample Rate Conversion On Audio Input Select Any even including Dual AES or Quad AES at higher Input Sample Rates Sync Source Any Input sample Rate Any Output Sample Rate n a Output Mode DSD Filter Any Output Wordlength n a Noise Shaping n a Dither n a Detect Silence n a As an example load Store H to take an input from AES1 and convert it to DSD SDIF 2 or DSD Quad format dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Using a Master Clock DIGITAL OUT WORDCLOCK IN Hand Crafted by N l I I The Red Hot CD Playe
7. 28 Figure 13 Multi channel Sample Rate Conversion with bit aligned source 29 Figure 14 Multi channel Sample Rate Conversion with Master Clock 30 Figure 15 Multi channel Sample Rate Conversion with more alignment TOI ue 31 Figure 16 Multi channel Sample Rate Conversion with multiple sample rates IR 33 Figure 17 Rear Panel EE 66 Figure To Front Fane kerrointa e a R a 68 Figure 19 Transient Performance of 44 1 kS s Filter Options 8 73 Figure 20 Transient Performance of 96 kS s Filter Options 00n00nn0ann00nnn 14 Figure 21 Wordclock and AES3 outputs 96 KS S 2 0 0 cceccceeeeeeeeeeeeeeaes 77 Figure 22 Wordclock and AES3 outputs 44 1 KS S 0 0 cece ceeeeeeeeeeeeeeaes 77 Figure 23 Wordclock in to Wordclock out Oopkis 78 Figure 24 Wordclock in to Wordclock out A4 1k is cc ceccceeeeeeeeeeeeeeees 78 Figure 25 AES3 in to AES3 out 96 KS S 0 0 cece cceececeeeeeseeeeeseeeeesaeesseaees 79 Figure 26 AES3 in to AES3 out 44 1 KS S 2 0 ccccceeeceeeceeeeeeeeeeeeeeeeeees 79 Figure 27 DSD data and Word clock out 80 Figure 28 44 1 kS s to 96 kS s PCM showing AES3 alignment 82 Figure 29 96 kS s to 44 1 kS s PCM showing AES3 alignment 82 Figure 30 44 1 kS s to DSD showing DSD bit alignment ee 83 Figure 31 DIner TEE 94 Figure 32 Dither Spectra FFTS nesiveiioies telstieeconaiciveena tenes ienoancls 9
8. Audio Input Select menu Use the rotary control to scroll down the list until the cursor is beside Quad AES Press the Set button to select it The screen will change back to the Sample Rate Conversion menu Proceed to Step 2 Connecting toa DSD SDIF 2 source Check that your source equipment is capable of DSD SDIF operation Connect the DSD SDIF 2 output on your source equipment to the upper block of DSD SDIF connectors on the dCS 974 rear panel using three coax cables Connect CH1 out to CH1 IN CH2 out to CH2 IN and CLK out to WCLK IN Fit a 75Q BNC terminating plug to the nearby LOOP OUT connector Press the button twice to enter first the Sample Rate Conversion menu then the Audio Input Select menu Use the rotary control to scroll down the list until the cursor is beside DSD SDIF 2 Press the Set button to select it There will be a noticeable delay while the DSD code loads then the screen will change back to the Sample Rate Conversion menu The dCS 974 will automatically detect either SDIF 2 or SDIF 3 Proceed to Step 2 Connecting to a DSD Quad source Check that your source equipment is capable of DSD Quad operation Connect the AES 1 output on your source equipment to the AES 1 input on the dCS 974 rear panel the AES 2 output to the AES 2 input the AES 3 output to the AES 3 input and the AES 4 output to the AES 4 input using four XLR cables Ensure the cables are connected in the correct order Press the button twice t
9. Balance and Maximise Swap Channels Phase Detect Silence De Pre Emphasis Display Customise Error Monitor Submenu Error Hold and Reset Test Submenu Generator Overview Controlling the Generator Generator Amplitude Adjustment Generator Frequency Adjustment Self Test Info Submenu Bit Activity Monitor Submenu Bit Activity Monitoring Overview Setting the Monitor Level Meters Submenu Level Meter Overview Turning the Level Meters On Meter Type Bar or Numerical Decay Time Peak Hold Using the dCS 974 to monitor a track Watch Out for this One Display Submenu Setups and Locking the Front Panel Storing a Setup Fixed Setups Recalling a Setup Locking Out Changes and Unlocking Again Rear Panel Signal Inputs Signal Outputs Control and Power Additional Information Front Panel Power Indicator OPERATION buttons MEMORY buttons LCD display LED indicators Rotary encoder Digital Data Formats Supported DSD PCM Input and or Output Performance Clocking Sample Alignment Multiple Channel Sync ing Multiple Channel Multiple Sample Rate Synchronising Noise Shaping Dither Digital Interface Specifications Message Handling AES EBU Message Handling SPDIF Message Handling May 2001 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 SDIF 2 Message Handling 90 SDIF 3 Message Handling 90 Power Consumption 91 Size Weight and Operating Conditions 92 ACS 974 Performance CGupves KKK KN RKNR ERR NKNR ERKENNEN KEN
10. DA96 Auto 96kS s input on AESI to Dual 24 96 Format Conversion On Recalling a Setup Stored setups may be recalled from memory at any time Press the Recall button once to display the list of user defined setups dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Either select one of these or press the Recall button again to toggle between the user defined and fixed setups ress 39a1lnh DA Aue 24 Oe GES ou Ha F2 AESI ou FCDA 96 24 dd A US02 CDOHS Fe scroll up or down to the required store and press the Enter button A message window will appear in the display to confirm that the unit is reading the setup When complete the display shows the Status screen for the current menu lf you make a mistake during a Store or Recall routine and you have not yet pressed Enter you can abort it by pressing any of the 4 Operation buttons Locking Out Changes and Unlocking Again Once the unit is set up it may be locked against casual interference by holding down the Status button and pressing the Store button THEEMS appears on the right hand side of the Status Error Monitor Test Mode Info Bit Activity Monitor or Level Meter screen as appropriate and the front panel controls have no effect To restore normal operation hold down the Status button and press the Edit button The Us label will disappear and normal operation will be resumed dCS 974 User Manual Manual for Software Version
11. Electrical Characteristics IMPORTANT The upper DSD SDIF WCLK IN connector loops through to the upper LOOP OUT connector to allow an external Wordclock to be daisy chained The last unit in the daisy chain will need a 75Q2 BNC termination connected to the upper LOOP OUT SPDIF electrical Input Output Type Single ended ground referred Impedance 15 15 Q Sensitivity unloaded 0 5 1 0 V pk pk Maximum Wordlength 24 24 bits Connector RCA Phono amp BNC Table 13 SPDIF Interface Electrical Characteristics dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 SPDIF optical Input Output Type Optical Maximum Wordlength 24 24 bits Wavelength 660nm Connector Toslink EIAJ CP 340 Table 14 SPDIF Optical Interface Characteristics IMPORTANT The Toslink interface is not specified for operation at 88 2 or 96 kS s due to limitations in the Toslink devices In practice the interface has been shown to operate correctly with other dCS equipment at all sample rates up to 96kS s_ but dCS cannot guarantee this due to Toslink manufacturing variations dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Message Handling The dCS 974 strips the message information from the incoming data The message in the outgoing data is set using the AES Message Edit and SPDIF Message Edit menus located under the Sample Rate Conversion menu AES EBU Message Handling The AES3 1992 standard was written
12. Error Monitoring screen To view this go to the top level menu select Error Monitor and press Status Error Monitoring CEC Errors LHE amp Parity Errors LHF amp Invalid Flags LHE amp This shows the error count on Left and Right channels separately since the last reset Error Hold and Reset Select the Error Monitor menu and press gt to display the next level menu Error Monitor C Errors Left CRO Errors Right Parity Errors Left Parity Errors Right Invalid Errors Left SE Errors Right Press again to display the options for CRC Error Left Error Monitor Errors Left BHold Reset Select either Hold or Reset and press Set The screen display changes to the Error Monitoring status Hold stops the count for that error type and Reset sets the count to zero Each error count may be stopped or reset in this way The A menu applies the changes to All Errors dCS 974 User Manual dCs Ltd Test Submenu Generator Overview IMPORTANT Manual for Software Version 1 0x May 2001 The dCS 974 includes a high quality digital signal test generator with both sine or square wave outputs and displays its settings on the Test Mode screen When invoked the generator adjusts its output format to that currently operating and substitutes the generated output for any input signal The generator operates at the output sample rate In PCM modes it is a PCM generator in the appropriate mode in DSD mode it
13. Filter 2 there is a choice of 4 The SonicStudio uses 24 96 as double speed AES at the time of writing Connect Sonic Solutions SonicStudio workstation AES output to AES 1 input on the dCS 974 Load the setup from Store K or use the settings below Output from any AES output or any of the SPDIF outputs or using two data cables and one clock via the SDIF 2 outputs Sample Rate Conversion settings Sample Rate Conversion On Audio Input Select Sync Source Input Sample Rate Output Sample Rate Output Mode Filter Output Wordlength Noise Shaping Dither Detect Silence AES Message Edit SPDIF Message Edit Gain AES Audio Input Auto 96 kS s 44 1 kS s Normal Filter 2 16 9th Order Off On Professional Off Non Audio Off Mode Stereophonic Professional Off Non Audio Off Permit On Format Compact Disc 0 1qB MAINS FUSE 2AT ON OFF Copy dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Demultiplexing a 24 96 Dual AES recording Bit for Bit From 24 bit 96kS s Dual AES source are connected correctly AES 1 Left data AES 2 Right data e e E male A o A D oO 24 bit 96kS s from 24 bit 96kS s 24 bit 96kS s 4 independent AES outputs from 3 independent SDIF 2 output SPDIF outputs Figure 7 Converting dual AES 24 96 to a single wire double speed one The dCS 974 converts a 96 kS s 24 bit Dual AES input to
14. IN is used as a sync source in and out are related as below The lower waveform is the output the upper one is the input For 44 1 kS s out leads in by about 500 ns and for 96 kS s it is about 230 ns fe running 1 2 90 div BA lim 2 500 VM 1 000 1 1M de 2 2 00 Vrdiy pos 2 000 1 000 7 30s de 1 0000 us O 000 g 1 0000 us 200 ns div repetitive Trigger Mode Edge 1 f 2 250 Figure 23 Wordclock in to Wordclock out 96 kS s Zoo running 1 2 90 diw DN lim 2 500 VM 1 000 1 1M de 2 2 00 Vrdiy pos 2 000 1 000 7 30s de 2 5000 us O 000 zs 2 J000 Us 3090 ns div repetitive Trigger Mode Edge 1 2 250 Figure 24 Wordclock in to Wordclock out 44 1 kS s If tighter alignment of WCLK IN to WCLK OUT is needed consider using a dCS 992 Master Clock where the phase of individual word clock feeds is adjustable or contact us 18 If this misalignment causes you a problem please contact us dCS 974 User Manual dCS Ltd Manual for Software Version 1 0x May 2001 AES3 in and out are related as below where they are at the same sample rate and the AES3 input is used as a sync source The alignment is better than 40ns Input is at the top of the displays output is at the bottom Signals are at the sockets on the dCS 974 fe running d 2 00 M 0Iy DN lim 4 500 w 10 00 1 1M de D 2 00 Vedi pos 4 000 10 00 1 Ms de 1 0000 us O 000 s 1 0000 us 200 ns div repe
15. Ltd Input Sample Rate Output Sample Rate Manual for Software Version 1 0x May 2001 For PCM input modes the input sample rate can be sensed and set automatically using the Auto option or forced The latter is useful where use of 1 or 2 wire mode for higher sample rates might be ambiguous otherwise Auto is best It occurs at the bottom of the Input Sample Rate list Gang le Rate Conversion DEU Sample Rate 15 Ze S s 5 16k5 12k Gas 11 425k 5 5 WOU Oo Select the required entry from the list and press Set If you have selected Auto then the list changes when re entered samele Fate Conversion Ineut Sample Rate BAuWLo E and the Status display will indicate that Auto is on Input AES Audio Input Modes Hormal W Length 244 bits H Share Off Output Sample Rate is a parameter for PCM output modes only Select the required Output Sample Rate from the list and press Set The dCS 974 accepts 112 input output sample rate combinations including DSD in one pass The remaining 70 combinations can be accommodated in 2 passes These are shown in Table 2 overleaf Not all the apparently valid output sample rates may be available to you from the menu When Auto Input Sample Rate Selection is turned on the menu system dynamically alters the Output Sample Rate menu to reflect the valid 1 pass output rates for the current input rate For example if Auto is turned on and the input is running at 96 kS
16. SDIF 2 PCM or DSD or SDIF 3 DSD only WCLK IN may be used to sync the unit to an external reference wordclock while taking data from another input WCLK IN is internally wired to LOOP OUT allowing a reference wordclock to be daisy chained through several units When the daisy chain is not used the LOOP OUT connector must be fitted with a 5Q BNC terminator WCLK IN will also accept a 10 MHz GPS reference dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Signal Outputs AES EBU Digital Outputs 3 pin XLR Male 4 off AES 1 AES 2 AES 3 AES 4 Used for AES3 format signals AES 1 and AES 2 or AES 3 and AES 4 are used together in Dual AES mode All four outputs are used together for Quad AES or DSD Quad modes In single AES modes AES 2 AES 3 and AES 4 outputs follow the AES 1 output AES EBU Clock Output 3 pin XLR Male 1 off AES CLK OUT AES CLK OUT carries an AES3 clock signal at the same sample rate as the AES 1 output It is used for synchronising equipment connected to the outputs of the unit SPDIF Outputs Various 3 off RCA OUT BNC OUT TOS OUT Used for SPDIF outputs Pull the plastic dust cover out of the TOS output before use DSD SDIF Output BNC 3 off CH1 OUT CH2 OUT WCLK OUT The lower group of three DSD SDIF connectors form an output interface Used as a set for SDIF 2 PCM or DSD or SDIF 3 DSD only outputs WCLK OUT carries Wordclock at the same rate as that appearing on the A
17. Slave If there is no sync signal coming into the AES Ref Loop In it will set up as a Master See section Multiple Channel Sync ing page 81 for an explanation or the multi channel applications from page 29 for wiring Do not feed a signal with active User bits into AES Ref Loop In with Multiple Channel Sync turned on When the option is On the Status display informs you about the unit s configuration If an active signal is connected to the AES Ref Loop In but it does not carry User bits the unit thinks it is a Single unit and the Status display is as follows Tneut AESI Sync Audio Input OP Mode Hormal LU Length 24 bits H Shares OFF If no signal is connected into the AES Ref Loop In there is no sync link going in the unit thinks it is a Master and the Status display is as follows Input ABST Sync Audio Input OP Mode Hormal P LU Length 24 bits AB H Sharer Ort Bal L db KR db If the sync link is connected and active the unit thinks it is a Slave and the Status display shows Ot 44 1 ks Input AESI Sync Audio Input OP Modes Hormal Sl ave LU Length 24 bits Gain E amp dB H Share OF f Bal L AdE F gE For multi channel syncing on DSD to DSD the sync link does not synchronise all the output Wordclocks Each unit will have a different phase Just use the Wordclock from one unit and ignore the rest the group delays for the signals will not be affected dCS 974 User Manual dCs
18. a double speed 96 kS s 24 bit signal available from any or all of the 4 AES 2 electrical SPDIF optical SPDIF or SDIF 2 outputs When using the Format Conversion menu the operation is bit for bit on the audio data messages can be edited Connect Nagra D Genex G 8000 SADIE Lake DSP etc dual AES source to inputs AES 1 and AES 2 on the dCs 974 Load the setup from Store J and set Pure Format Conversion to On or use settings below Output from any AES output or any of the SPDIF outputs or using two data cables and one clock via the SDIF 2 outputs The outputs will all be at double speed Format Conversion settings Pure Format Conversion On Audio Input Select Dual AES Sync Source Audio Input Input Sample Rate Auto 96 kS s Output Sample Rate 96 kS s Output Mode Normal AES Message Edit Professional On Non Audio Off Mode Stereophonic SPDIF Message Edit Professional On Non Audio Off Copy Permit On Format 2 Ch Gen Format dCS 974 User Manual dCs Ltd Upsampling a CD DIGITAL OUT CLOCK IN 24 bit 96kS s or 192kS s Dual AES to DAC Manual for Software Version 1 0x May 2001 Hand Crafted by The Red Hot CD Player Co Figure 8 Upsampling a CD to 24 96 or 24 192 The dCS 974 converts a 44 1 kS s 16 bit SPDIF input to a Dual AES 96 kS s 24 bit signal available from AES 1 amp AES 2 outputs There is no information added in the process although you may wish to check theory here C
19. are rae oe J 5 00 Ydi ABH lim 8 000 Y 10 00 1 ne de DN ENEE EE RE OO E 2 5000 us O 000 g 2 2000 US 200 ns div repetitive Trigger Mode Edge E 2 500 Figure 29 96 kS s to 44 1 kS s PCM showing AES3 alignment dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Se running 1 3 00 W div DN lim 56 250 VM 10 00 1 Ms de 2 5 00 Vrdiv DN lim 8 000 10 00 1 ia de 1 0000 us 0 000 zs 1 0000 us 200 ns div repetitive Trigger Mode Edge E 2 500 Figure 30 44 1 kS s to DSD showing DSD bit alignment Multiple Channel Multiple Sample Rate Synchronising DVDs can make use of mixed sample rates in their multi channel mode for example 96 kS s in the front channels and 48 kS s in the rear channels As well as the problems mentioned above in the section Multiple Channel Sync ing use of multiple channels brings an additional problem in that the group delay in the sample rate conversion process varies with the sample rate It generally gets longer as the sample rate gets lower making the rear channels seem further away than you might want Figure 16 shows how a master clock may be used with several dCS 974 s in parallel to get simultaneous synchronised sample rates out at the same time Please contact dCs if you need support for this process dCS 974 User Manual dCs Ltd Noise Shaping 22 Manual for Software Version 1 0x May 2001 The dCS 974 uses noise shapin
20. arrows point to the digit that you want to edit press the Set button The knob will now increment or decrement the selected digit If you increment the digit beyond 9 then the next digit gets incremented and the current digit is set to 0 Similarly if the digit is at 0 decrementing it will change the previous digit s For example the above display shows 1kHz If we decrement the 0001 digit the result is as follows PP igrnal a Shae i VW E When you have set the frequency you want move the arrows to the symbol and press Set To discard the changes and return to the tone generator menu move the arrows to the X symbol and press Set dCS 974 User Manual dCs Ltd IMPORTANT Self Test Manual for Software Version 1 0x May 2001 outputFs If you select a frequency that is more than gt the frequency generator will outputFs automatically be set to a Select Generator Off and press Set it will toggle to Generator Sine Wait several seconds for the code to load up then press again and it will change to Generator Square Press again and it will return to Generator Off Press Status to display the Test Mode screen In J Bks Cat 44 1 Gas Waveform Generator Sine AmMelitude 12 gE Frequency SL H tt Hz The ISO label appears on all status screens while the generator is on With the Generator On the signal path from the selected input is disabled and replaced by the Test Generator signa
21. eeeeeeeececececececeeeees 69 INGICATOFS LED i cowich ernie aoc E N 69 HMen EE 39 56 Input Sample Rate menu 43 Input Sample Rate Auto 43 input selection cccec cece eeeceeceeeeeeeeeeees 11 41 Iuieif GR RT 66 Ile 66 INPUT VV OFACIOGK EE 66 Inte 66 Mpu SPDIF EE 66 internal SynCare e 41 Invalid Fs In for Fs Out 44 Invalid Fs Out for Fs In eee 122 ISSUE software 56 J jitter reducing anoanonnannannnnnnnnnannnnnnnnnnnne 13 28 L UR G lle IGICALOR EEN 69 Lab Ref SYNC mode 41 Bebon EE 68 Sb iaieie ele 69 RRE EE 40 57 Level Meters ticker 59 Level Meters bandwidth cceeeeee es 57 Level Meters clip mdicaton 57 Level meters decay me 58 Level Meters decay me 58 Level Meters DD 40 57 59 Level Meters numercal 57 Level Meters peak hold 08 57 58 Level meters setting the bandwidth 59 Level Meters fvpe ANN 58 loading a default setunp 10 IOC KK CIE EE 120 lock failure destination device 120 locking front panel 64 Beie deif let 64 Lockout setting and unsetting 64 low output bandwidth ccceceeeeeeeeeee es 121 M maintenance regular scene 116 Master Clock using 13 14 27 30 31 32 Maximise fails to output full scale 121 Maximise menu 48 dCS 974 User Manual dCs Ltd Maximise USIN anoanannanoanannanonnnnnannnnnnnnnnnne 49 Memory butto
22. for Software Version 1 0x dCs Ltd May 2001 STEP BY STEP GUIDE This section guides you through setting up the unit for basic operation You may find this useful if you have not used the dCS 974 for a while Preliminaries The Quick Start Guide sheet details the menu structure and outlines the use of the front panel controls For more information see Navigating through the Menu what the On Screen symbols mean on page 36 and The Software Menu and Setups on page 34 We will be changing settings in either the Sample Rate Conversion menu or the Format Conversion menu Use the rotary control to scroll up and down the screen and the Operation buttons to change menu levels or select items Connect up with cables designed for digital audio e for AES EBU interfaces use 110Q screened twisted pair cables fitted with one male XLR connector and one female XLR connector e for DSD SDIF or SPDIF BNC interfaces use 75Q coax cables fitted with BNC plugs e for SPDIF RCA interfaces use 75Q coax cables fitted with RCA Phono plugs e for SPDIF TOS interfaces use Toslink fibre optic cables Power up the unit and wait for about 20 seconds while it configures itself The screen will show Data Conversion Systems Press the Recall button When the screen displays the Recall Setup list press the Recall button again to change to the preset setup list then press the Enter button Wait while the unit loads the default setup Store A then di
23. from this you can Recall a stored setup known to have a higher contrast setting see the next section If the worst happens and none are available switch off the unit then hold down the Status button while switching on The unit will display Using Default Settings and will load a setup with high contrast The third option Cursor controls the way the cursor responds to turning the encoder The default setting is the cursor moves down if the encoder is turned clockwise If you prefer the opposite arrangement move the cursor to the bottom line and press Set Clockwise Down changes to Clockwise Up Pressing Set again change back The fourth option determines the time after which the display backlight goes out The backlight is an electroluminescent device and so in theory has limited life It can also buzz a little and although we select for low buzz and acoustically damp it it can be irritating So the display goes dark after a preset period although pressing any button or turning the knob will wake it up again When the cursor is against the Backlight Off After option each time you press Set it steps through the settings min 3 min and 5 min dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Setups and Locking the Front Panel Storing a Setup The dCS 974 features 12 non volatile user programmable setup stores labelled Store O to Store 11 These are accessed by the rotary control and the block
24. list are indicated by the X sign in the box next to it For example amk le Fate Conversion Disrlas Customise BE DRFut E SiC O P Mode LU Length Share O Dither indicates that the five displayed parameters are Input Sync O P Mode W Length and N Shape Dither and the options further down the list are not displayed dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 To display a parameter that is not marked first check that no more than four parameters in the list are marked If so select the extra parameter and press Set an X sign will appear in the box next to it If five parameters are already marked select an unwanted one and press Set the X sign will disappear Then select the wanted parameter and press Set The parameters available are Input Audio input selection Sync Synchronisation source O P Mode Output mode W Length Word Length N Shape Noise Shaping characteristic applied Dither Displays Dither type used L R Flip Filter Displays Filter Cut used With the top five parameters selected the Status screen might look like this Input AESI Audio Input Lab Modes Hormal LU Length 24 bits H Share Off With the bottom four parameters selected the Status screen might look like this dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Error Monitor Submenu The dCS 974 keeps count of CRC Parity and Invalid errors and displays them on the
25. low perceived weighted noise power This last is a significant test of generator performance the dCS 974 performs very well Performance curves for all these settings including PDFs of the added dither are given in the dCS 974 Performance Curves page 94 The noise added by the dither settings is summarised below Dither Type Noise Added Noise Perceived Power Power Noise 0 Fs 2 unweighted Added F weighted No dither straight truncation Top Hat dither Triangular dither Noise Shaped Triangular dither Table 10 Noise Added by Dither Types If dither is used it is shaped made less audible by noise shaping This applies as much to noise shaped triangular as the others dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Digital Interface Specifications AES EBU AES3 Input Output Type Balanced differential Impedance 110 110 Q Sensitivity unloaded 1 10 7 V pk pk Maximum Wordlength 24 24 bits Connector XLR3 female XLR3 male Connections Pin 1 Ground or shield Pin 2 Signal Pin 3 Signal Table 11 AES EBU Interface Electrical Characteristics SDIF and DSD Input Output Upper block Lower block Type Single ended ground referred Impedance 100 CH1 2 59 Q 1k WCLK Sensitivity unloaded TTL TTL Maximum Wordlength 24 24 bits Connector BNC x 4 BNC x3 Connections CH1 IN CH1 OUT CH2 IN CH2 OUT WCLK IN WCLK OUT LOOP OUT Table 12 DSD SDIF Interface
26. of four MEMORY buttons on the lower left hand corner of the unit First set up the unit as required then press the Store button If nothing has been stored yet the display will look like this dEraptoaz lt Emrty gt Empet Emr dEraptoaz Emr t gt Emp t a LE J LR 11 Hs 1 S AP You can scroll up and down the list using the rotary encoder and reveal the other five stores Scroll to the required store e g Store 4 and press the Edit button The display changes to EME t a eed Zei T To edit the first character in the name press the Edit button again The display changes an alphanumeric screen is displayed with the current store name at the top and all of the legal characters below it as follows m he S ai op de wz Turn the knob to move the edit block 3 backwards and forwards through the available characters The arrow indicates which character you are editing and the character is updated in real time as you move the edit cursor The el symbol represents lt End gt When you have finished editing the character press the Edit button to return to the previous screen and select the next character to edit Names can be up to 15 characters long plus an lt End gt character to mark the end of the name If all 15 characters are used and you attempt to edit the lt End gt character in the 16th slot the Edit button has no effect Inserting lt End gt half way through a name wi
27. page 22 detailed software and hardware information page 34 technical information page 70 information for first time users page 110 options maintenance and troubleshooting page 114 index section page 124 References to other sections in the text have the Section Name page with Section Name in bold Sometimes if you are reading a soft copy of the manual section names and page numbers are hyperlinks click on them and you will go there IMPORTANT Important information is presented like this ignoring this may cause you to damage the unit or invalidate the warranty The manual is designed to be helpful If there are points you feel we could cover better or that we have missed out please tell us About Sample Rates All references to sample rates in this manual use the unit kS s kilo Samples per second rather than the technically incorrect KHz dCS 974 User Manual dCs Ltd CONTENTS Product Overview Contents Step by Step Guide Typical Applications The Software Menu and Setups Manual for Software Version 1 0x About this Manual About Sample Rates Preliminaries Step 1 Selecting an Input Connecting to a Single AES or SPDIF source Connecting to a PCM SDIF 2 source Connecting to a Dual AES Source Connecting to a Quad AES source Connecting toa DSD SDIF 2 source Connecting to a DSD Quad source Step 2 Setting the Sync Source Syncing to an External Wordclock Syncing to an AES EBU
28. remote COMO eener ee 67 rotary encOoder 69 S STA O D ere 71 Sale rine ee a rea Ga ee a al 119 Sample algnment 17 sample alignment AES3 in to oult 19 sample alignment AES3 to Wordclock Tf SAM PIC EE eeh 5 sample rate combinations cccceee eens 43 sample rate Conversion es 16 25 Sample Rate Conversion menu 41 Sample Rate Conversion mode 38 sample rate Input 43 sample rate output ccceeeeeeseeeeeeeees 43 SDIF IMENI C E 86 HEED 66 SDIF 2 input selechnmg 11 SDIF 2 message bhandlumg 90 SDF OUND EEN 67 SDIF 2 output connecting eee eens 18 selecting a single wire Imput 11 dCS 974 User Manual dCs Ltd Selecting AN Input 11 selecting DSD Quad input eee 12 selecting DSD SDIF mput eee 12 selecting Dual AES mput eee 12 selecting Quad AES mput cece 12 selecting GIDIE Zmput 11 Self Test display cccccsseccseeeceeeeeeeeesaees 55 serial number unft cee cecceeeeeeeeeeeeeees 67 EE 118 EE E 68 setting output mode cee ceeeeeee ees 15 17 setting output sample rate eee 16 setups Ten ee 63 SEENEN 61 Signal generator NEE 53 Single AES output connecting 00 18 single wire output mode 45 single wire Outputs FC 15 single wire outputs GR 17 SIZ Gs eege Eege 92 software Lesue 56 software updates downloading 0010 67 software version ccceecceeceeeeeeeeeeeeeeeeeeeee
29. signal FFT with and without dither Noise Shaper and Noise Shaper with Dither Performance dCS 972 SW v1 54 60 sew 16 bit truncation 10th order noise shaping no dither Se 16 bit truncation 10th order noise shaping Top Hat dither 16 bit truncation 10th order noise shaping Triangular dither E i Zv Ban D 16 bit truncation 10th order noise shaping Noise Shaped Triangular dither SCH FO Petal raed pan IN GET app S S eng 100 a A a e g jy 5 Fi S 120 AJ A jj 7 Ze AT reet Ke AN D st Ce TS Y S Wach K SC E K SE ep bes KE 7 i lt p S G 140 E Kg G CS Zem den E 160 0 2 4 6 8 10 12 14 16 18 20 22 Frequency kHz Figure 35 Truncated small signal FFT showing noise shaping with and without dither dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Spot Q Noise for DSD Filters in 400 Hz bandwidth eid 20 F2 F3 wem e F5 F6 F7 a 120dB in 20 kHz 100 120 Q Noise rel Full Scale DSD dB 140 1 6 0 8 C 200 1 10 100 1000 Frequency kHz Figure 36 DSD output spot Q Noise for the various Filter options Integrated Q Noise for DSD Filters normalised for Full Scale DSD at 0dB 20 00 Ei 0 00 F2 F3 20 00 A F4 F5 F6 E 40 00 60 00 80 00 100 00 Integrated Q Noise Power dB 120 00 Le EH e ee 140 00 ee Z 160 00 180 00 1 10 100 1000 Freq
30. source equipment and ensure it is locked Connect another Wordclock output from the Master Clock to the WCLK IN connector upper block of DSD SDIF connectors on the dCS 974 rear panel Fit a 75Q BNC terminating plug to the nearby LOOP OUT connector If the source equipment uses SDIF 2 in either PCM or DSD mode the Wordclock feed from the Master Clock replaces the Wordclock feed from the source equipment Scroll down the Sample Rate Conversion menu to Sync Source and press the button Scroll down the list to Wordclock and press Set The Unlocked indicator will light for a few seconds then turn off as the unit re locks Proceed to Step 3 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Syncing to an AES EBU Reference If you want to synchronise your system to an AES EBU Reference from a Master Clock such as the dCS 992 or other stable source do the following Set the Master Clock sample rate to match the source probably 44 1 or 48kS s Connect either an AES EBU or Wordclock output from the Master Clock to the clock input on the source equipment and ensure it is locked Connect another AES EBU output from the Master Clock to the AES Ref Loop IN connector on the dCS 974 rear panel Scroll down the Sample Rate Conversion menu to Sync Source and press the button Scroll down the list to AES Loop Terminated and press Set The Unlocked indicator will light for a few seconds then turn off as the u
31. this mode the AES Clk Output and 3 SPDIF outputs all carry identical AES streams with no data they may be used for synchronisation The SDIF Clk Output sends Wordclock at the same rate as on AES 1 do not use the SDIF data outputs while in Quad AES mode Otherwise set to Normal for single wire outputs on AES 1 AES 2 AES 3 amp AES 4 the three SPDIF outputs and the SDIF 2 output For PCM out the unit can have PCM or DSD in The dCS 974 offers a choice of filter for use on some of the more popular in out combinations The filters offer differing responses For PCM outputs Filter in each case offers the sharpest cut off and no or least aliasing but longest energy smear Filter 4 gives the gentlest roll off usually with significant aliasing but the shortest transient response with least smear For DSD output the differences are not so great the responses are given in the section dCS 974 Performance Curves page 94 The conversions that offer multiple filters are as follows dCS 974 User Manual dCs Ltd Output Word Length IMPORTANT Manual for Software Version 1 0x May 2001 Out Number of Filters Available DSD DSD 8 PCM DSD 8 192 96 4 176 4 88 2 4 176 4 44 1 4 96 48 4 96 44 1 4 88 2 44 1 4 48 44 1 4 44 1 96 4 Table 3 Conversions with Multiple Filter Options We encourage you to experiment with the filters to find the one that sounds best for your particular application Do not assume that one filte
32. 10 seconds then switch on normal operation should be resumed The stereo image is poor or out of position e Check that Phase and Swap Channels are set to Normal e Check that Balance is correctly set e t may be that the input signals are out of phase swapped or out of balance Use the units controls to correct this e If using the DSD SDIF interface the CH1 amp CH2 cables may be swapped e f you are using a Dual AES or Quad AES mode from some other equipment make sure you used the right outputs from that Maximise fails to increase the signal level to full scale e The range of the Maximise function is limited to 12dB If the input signal peaks are smaller than 12dB0 Maximise will apply 12dB of gain A second pass will apply up to 12dB more gain dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Invalid Fs Out for Fs In message Sanrle Rate Conversion i Invalid Fs Out for Fs In Press Set to alter Fs In ans other key to cancel e You have selected a combination that cannot be handled in one pass see the table in the section Output Sample Rate on page 43 for valid single pass combinations Choose an intermediate sample rate and convert in two passes For example if you need to convert from 32 kS s to 11 025 kS s first convert to 44 1 kS s and record then convert the recording from 44 1 kS s to 11 025 kS s e While changing frequencies you have accidentally selected an interm
33. 115 V so it only blows if there is a fault usually if the unit is set to its low voltage setting 100 120V but has been plugged into a high voltage supply 220 240V Usually no other damage is caused but if the fuse blows repeatedly on replacement some other damage will have been done and the unit must be returned to dCs for repair Fuse Type 20 x 5mm 2 amp HRC fuse If the fuse should fail it is essential that it be replaced with one of the same type Failure to do so could result in damage to the unit and may invalidate the warranty To gain access to the fuse remove the IEC mains connector use a small flat bladed screwdriver to pry up the tab on the fuse carrier and pull it out Push the fuse out of the clip in the carrier and replace it with a new one Push the carrier back into the unit so that it clicks home dCS 974 O more dcsltd co uk MAINS FUSE 2A T ON OFF Remove Fit old fuse new fuse sa BY Figure 51 Changing the Mains Fuse IMPORTANT Disconnect from the supply before changing the fuse dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Software Installing New Software There are two major components of software in your unit These are the operating software and the display software The operating software can be downloaded via the RS 232 link from a PC COM port using the Windows Remote software running on the PC To use this follow the installation instructions on the flo
34. 120dBO Unconditionally free from truncation effects with all inputs DSD carries this further The principle is the same but with DSD there is more noise than there is signal even at full scale It is just that it is in a part of the spectrum the ear cannot hear 30 46 bit Q noise is 98 1 dB relative to a full scale sine wave dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 Noise shaping on its own is not perfect It relies on a small amount of noise in the input signal to generate the frequency shaped correction signal and if there is very low noise in the input signal this mechanism can break down In reality such a situation can only occur with test signals digitally generated signals or silences introduced in editing If one of these situations may arise any chance of a problem can be completely removed by adding a dither signal as well as using noise shaping The noise shaping shapes the dither in the dCS 974 architecture If Noise Shaped Triangular dither is used then there is very little weighted degradation in the final signal although the quite high level of total noise power now present means that the process should be carried out after major editing There is another option not supported by the dCS 974 generate the dither independently of the signal and frequency shape it prior to addition but do not add it in an error shaping loop This seems to dCS to combine the worst of all wo
35. 15 17 output Mode single wire 45 output quality IS poor 120 Output Sample Rate menu 43 output sample rate setting ee 16 Output Word Length men 46 output AES CIOCK EE 67 Out DSD SD MF E 67 OUN SDI 2 arn a A i 67 Output WOrdCloCK isinna 67 OUOU E 67 outputs connecting fo 18 GH SPDIF tee 67 Manual for Software Version 1 0x May 2001 Owner registration cccceeeseeeeeeeeeeeeeeees 118 owner registration transfer c0000 131 P POM TO DSD EE 26 performance CUIVES cccccceeeseeeeaeeeeeeeeeeees 94 Phase indicators cece cecceeeeceeeeeeeeeeeeeeees 69 phase locked oop n nannnnnnnnnnnnnnannnnnnnennnnnnnnne 76 Phase menu 49 eeben 76 ME ele ln El EEN 76 PLL pull in FANG EN 76 poor Output quality ce eceeeeeeeeeeeeee ees 120 power COnSUum Don 91 Power indicator annannannnnennannnnennnnnnnnnnnnne 68 DOWN Mle larerrne a nails auensialndass 67 powering Up EE 10 110 Pre Emphasis men 50 pure format conversion ccseceeeeeeeeeeeeees 39 Q Quad AES input selechng 12 Quad AES output Mode cccceeceeeeeeeees 45 Quad AES output connecting a0a0a0000n 18 Quad AES output EC 15 Quad AES output GR 17 Quad AES to CD format ee eeeee 28 R leeft Le ME 112 rear DANG ie DEE 66 Recall DUWOM EE 63 68 recall aborting E 64 recalling a Setup 63 recalling the default setup ceee 111
36. 16 kS s 12 kS s Dual AES 1 2 Quad AES SPDIF1 RCA SPDIF2 BNC SPDIF3 TOS PCM SDIF 2 DSD SDIF 2 or 3 DSD Quad 192 kS s 176 4 kS s 96 kS s 88 2 kS s 50 kS s 48 kS s 44 1 kS s 32 kS s 24 kS s 22 05 kS s 16 kS s 12 kS s 11 025 kS s Auto 11 025 kS s are not there when Format Conversion is On They prevent bit for bit operation DSD 64 44 1kHz Normal Dual AES Quad AES DSD SDIF 2 DSD SDIF 3 Output Mode Filter 1 Se Filter 2 F Se n Output Word Length 5 Ge Off e Noise Shaping EE a 10th Order Off Top Hat Triangular Noise Shaped Triangular Dither AES Message Edit Professional On Off Not Indicated Two Channel Single Channel Primary Secondary Stereophonic Non Audio On Off Menu entries in italics and the menus below them may disappear if the selection of other parameters makes them Mode Source Byte 1 Source Byte 2 Source Byte 3 Source Byte 4 Source Destination Byte 2 Destination Byte 3 Destination Byte 4 Destination unrealistic SPDIF Message Edit Professional On Off This mainly happens with DSD on Non Audio On Off Copy Permit On Off 2 Ch Gen Format Compact Disc 2 Ch Enc Decode DAT Format dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Gain adjust Gain Balance Balance adjust Reset max hold Maximise Maximise Maximise Normal Swap Channels Swapped Normal Left i
37. 2 27 130 14 27 13 31 99 noise 6 Single 110 78 151 02 25 19 23 55 complex zero 7 Real zeros 101 5 132 41 25 29 27 04 SACD Spec 20 00 28 00 Table 5 DSD Filter Performance DSD Data Formats DSD is supported on SDIF 2 SDIF 3 and DSD Quad formats Ke Super Audio CD System Specifications Part 2 Audio Specifications available from Philips System Standards and Licensing Licensing Support Building SFF 8 PO Box 80002 5600 JB Eindhoven The Netherlands dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 PCM Input and or Output Performance Filtering The normal filtering considerations of passband ripple cutoff frequency and rate out of band stop band suppression and transient phase response apply to sample rate converters The dCS 974 uses linear phase FIR filters to avoid the limit cycle problems that come with many IIR filters Linear phase gives filters a symmetrical transient response before and after a transient pre ringing and post ringing The passband may or may not have a ripple De depending on the conversion and or filter being used Cutoff feig E gt 40 of the lowest sampling rate used in the conversion input or output The stop band is typically below 110 dB but varies with conversion and can be as low as 130 dB The frequency responses of two commonly used conversions 96kS s gt 44 1kS s and 48kS s 44 1kS s are shown in Figure 41 and Figure 40 on
38. 24 bit 176 4kS s or 192kS s Quad AES format using a standard 8 track digital recorder then convert to other formats such as Red Book CD Sample Rate Conversion settings Sample Rate Conversion On Audio Input Select Quad AES Sync Source Audio Input Inout Sample Rate AUTO Output Sample Rate 44 1kS s Output Mode Normal Filter Any Output Wordlength 16 Noise Shaping 9th Order Dither NS Triangular Detect Silence On Provided the Output Sample Rate is set to one quarter of the Input Sample Rate i e 176 4kS s 44 1kS s or 192kS s 48kS s you can reduce jitter by using the dCS 974 as the master clock and locking the recorder to it Change Sync Source to Internal connect WCLK OUT lower block to the recorder s Wordclock input and set the recorder to slave Archive at 176 4kS s for audio based material archive at 192kS s for video based material Ensure the sample rates match the source material dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Multi channel Sample Rate Conversion bit aligned sources 96kS s Ch1 amp 2 EE een e 96kS s Ch3 amp 4 44 1kS s SOURCE 96kS s Ch5 amp 6 96kS s Ch7 amp 8 CH1 IN o N WCLK IN Fa 1 Q D e o CH OUT el Q Qa Figure 13 Multi channel Sample Rate Conversion with bit aligned source If the source data is bit aligned for example from a multitrack recorder up to four or five dCS 974 s ma
39. 26 46 30 87 35 28 Frequency kHz Figure 40 48 kS s to 44 1 kS s conversion Filter responses 96 kS s to 44 1 kS s Filters dCS 972 SW v1 54 Filt 1 Filt 2 l i d A A Ry AN l d H Ai l a l 4 i d I d i d LA Il H ih D s EE E a 1 H d PIR VAL RAGA 8 82 13 23 17 64 22 05 26 46 30 87 35 28 39 69 Frequency kHz SC L l S if e ae d I ri l Figure 41 96 kS s to 44 1 kS s conversion Filter responses N AN dal 44 1 Response dB Passband Response dB dCS 974 User Manual dCS Ltd Noise Amplitude relative to No Shaping dB Noise Amplitude relative to No Shaping dB 24 36 30 24 18 Manual for Software Version 1 0x May 2001 32 kS s Noise Shape Plots dCS 972 SW v1 54 2nd or 6th Order Recommended 4 8 Frequency kHz Figure 42 32 kS s noise shaper curves 44 1 kS s Noise Shape Plots dCS 972 SW v1 54 2nd or 9th Order Recommended 4 8 12 Frequency kHz Figure 43 44 1 kS s noise shaper curves Order 1 Order Order 3 Order 4 Order 5 gt Order 6 Order 7 Order 8 Order 9 Order 10 Order 1 o Order 2 Order 3 Order 4 Order5 Order 6 Order 7 Order 8 Order 9 Order 10 20 dCS 974 User Manual dCs Ltd 48 kS s Noise Shape Plots dCS 972 SW v1 54 36 30 24 Noise Amp
40. 3 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 OPTIONS The following options may be fitted to new units or retrofitted at a later date Option code Option VID Locking to video sample rates V5 Mains voltage set to 230 240V V4 Mains voltage set to 215 220V V2 Mains voltage set to 115 120V V1 Mains voltage set to 100V Table 17 Options available Locking to Video Sample Rates We can fit additional video frequency VCXO s enabling frequencies such as 44 056kS s and 47 952kS s This option must be fitted at dCS to allow full checking Contact dCs for details Mains Supply Voltage Any unit may be set for operation from 230 240V 220V 115 120V or 100V A C The voltage setting can be updated later by your Distributor if necessary Specify the new voltage code Ordering Options for a New Unit To order any option check the option codes from Table 17 above and tell us dCS 974 with options lt option codes gt IMPORTANT You must specify a supply voltage option code Having Your Options Changed dCS support modifications updates and option changes to supplied units Major changes are normally carried out at dCS as we have extensive test facilities and can verify the changes Please contact your Distributor or dCS for details IMPORTANT Please do no
41. 4 AES Clock Output ccccccceceeeeseeeeeeeeeeees 67 AES input selecting 00nnnannannoannnnnnannnnnnna 11 Alle 66 AES EES 86 AES Message Edit menu 48 AES message handling aannannnannannnnannennna 88 AES Message User buts 42 AES OUMUTS esirin e 67 AES Ref sync tO ccsccescccseccsetsetseereceres 14 AES reference loop 66 ejeje erile Tu 22 Audio Input Select men 41 auto input sample rate eeeeeceeeeeeeeee es 43 B Backlight timeout ccccccccseeeeeeeeeeeeeeeees 60 Balance mdcator 69 Balance menu 48 Balance USING ccccceccceccseeeceeeeeeeeeeeseeeees 49 Bit Activity Monitor ccccccccceeceeeeeeees 40 56 bit for bit operation ccceceeeeeeeeeeeees 15 38 button 22 eee ec T 68 DUO EO IEN 61 68 button Enter 62 68 button Recall 63 68 button Gei 68 button Status 0 0 0 eeeeceeeeeececeseeeeeeeeeeeees 68 button Store cece eecececeecececeeeeeeeeseeeeaees 61 68 buttons Memory sanannannsnnnnnnnnsnnnnnnnrnnnnnne 68 buttons Operation ccccccceeeeeeeeeeeeeeeeeees 68 C CADES EE 10 CAMO U OWN EEN 119 can t lock to Generator output 000n00000an 53 Can t read display cccccccsseceseeeeeeeeeeeeees 60 clock ACCUIACY EE 76 clock Stabllity 0 cece ceecceeeceeeeeeeeeeeeeeeenees 76 Clocking miermal 76 connecting the outputs eeeeceeeee neces 18 contact i
42. 5 Figure 33 Small Signal Raw Data with Utbers cc ccceeccceeeeeeeeeeeeeeaes 95 Figure 34 Truncated small signal FFT with and without drther 96 Figure 35 Truncated small signal FFT showing noise shaping with and EIERE 96 Figure 36 DSD output spot Q Noise for the various Filter options 97 Figure 37 DSD Output integrated Q Noise for the various Filter options 97 Figure 38 DSD Output F weighted Q Noise for the various Filter options 98 Figure 39 DSD showing 0 dBO full ecalel ec ceccceseeeeeeeeeeeeeeeeseeeeeseaees 98 Figure 40 48 kS s to 44 1 kS s conversion Filter responses ann00nnaannan 99 Figure 41 96 kS s to 44 1 kS s conversion Filter responses a0nn00nnaannan 99 Figure 42 32 kS s NOISE shaper cunves 100 Figure 43 44 1 kS s noise shaper cuUmves 100 Figure 44 48 kS s noise shaper cumves 101 Figure 45 88 2 kS s noise ahapercuUmes 101 Figure 46 96 kS s NOISE shaper cumves 102 Figure 47 Noise shaper noise and weighted noise VS order 102 Figure 48 Noise Shaping and Dither Gpoecha 107 Figure 49 Truncation Only Gpechra 107 Figure 50 Noise Gain and Weighted Noise Gain by Shaper Order and Sample Ee 108 dCS 974 User Manual dCs Ltd Keywords and Phrases DURON EE 68 2 24 bit OPEration c cccccssseeceeeeeeeeeeeeeseeeess 19 Z4 0pGioChD 22 2 PASS COnversions 43 44 45 A aborting a store or recalt 6
43. 7 Group Delays PCM to PCM transitions dCS 974 User Manual dCs Ltd Clocking Internal clock Manual for Software Version 1 0x May 2001 The sample clock quality significantly determines the output performance of a DDC in as far as items connected may have to reconstitute an analogue signal and may ultimately derive their clock from the DDC clock The highest quality clocks that are available are crystals so we use these In Internal sync mode the dCS 974 uses one of two on board voltage controlled crystal oscillators VCXOs as clock sources one for 48 kS s related outputs and one for 44 1 kS s related outputs The internal VCXO is synchronised to the sync source which need not be the signal input by a phase locked loop PLL The PLL is of a special narrow bandwidth type that provides a significant degree of clock cleaning but even so signal quality may degrade if particularly poor slave clocks are used A consequence of the narrow bandwidth is that it takes quite a long time for the PLL to lock to a new clock frequency of the order of 2 seconds The PLL uses DSP assistance to keep this time acceptable The input data is extracted using an oversampled UART type of decoder This can tolerate quite jittery inputs whose phase is unrelated to the clock source used for locking The average frequency must be the same however Accuracy when shipped 10 ppm Long Term Stability 10 ppm year at room temperature Tempe
44. ACS 974 Digital to Digital Converter User Manual Software version 1 0x May 2001 2001 dCS Ltd All rights reserved Reproduction of this manual in any manner whatsoever without the written permission of dCs is strictly forbidden Additional copies of this manual may be obtained from dCs Information contained in this manual is subject to change without notice and whilst it is checked for accuracy no liabilities can be accepted for errors 1 dCS Ltd is Data Conversion Systems Ltd Company registered in the England no 2072115 dCS 974 User Manual Manual for Software Version 1 0x dCS Ltd May 2001 Manual part no DOC1241121A1 Page 2 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual dCS Ltd Manual for Software Version 1 0x May 2001 PRODUCT OVERVIEW Formats Functions Syncing The dCS 974 DDC Digital to Digital Converter is a high performance real time sample rate and format converter developed from our highly successful dCS 972 t is designed for studio applications where source material is available in one format but outputs are required in other digital formats in real time For example archives might be made for storage in 24 192 or 24 176 4 formats and then used to produce output in SACD DVD CD and other multimedia formats AES3 SPDIF SDIF 2 and DSD formats are all support
45. DSD SDIF 2 DSD SDIF 3 or DSD Quad Figure 9 General Sample Rate Conversion The dCS 974 converts any one of 12 sample rates in any format to any of the 12 sample rates in ALL formats 4 AES 2 electrical SPDIF optical SPDIF or SDIF 2 outputs Most frequency combinations including all the primary ones are accommodated in one pass see Table 2 on page 44 For best results slave the unit to the audio input AES Ref Loop In or the SDIF 2 WCLK IN Connect any digital audio source of any word length between 8 and 24 bits using single AES or dual AES or quad AES to the AES inputs or using single or double speed SDIF 2 to the SDIF 2 inputs or using single wire SPDIF to the appropriate SPDIF input Select Audio Input accordingly Output via any of the outputs Sample Rate Conversion settings Sample Rate Conversion On Audio Input Select Any including Dua AES if the Input Sample Rate is 88 2kS s or more and Quad AES if the Input Sample Rate is 176 4 kS s or 192kS s Output Mode Normal or Dual AES may be selected if the Output Sample Rate is 88 2 kS s or 96kS s Dual AES or Quad AES must be used for 192 kS s or 176 4 kS s Other settings Any 3 It has to be Dual AES or Quad AES for 192 kS s or 176 4 kS s dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 PCM to DSD From PCM in ANY format AES SPDIF Toslink or SDIF 2 at sample rates 44 1k 48k 88 2k or 96kS s or Dual AES at 88 2k 96k 176 4k or
46. E D M o U M os Si iy E a Kern E ee en EE SE E ee S v 120 Reeg ENV QAO POG HF x E AE ere i lt x io e l re Gei Fi AN gt r oe ET AR jo 140 ra LO d King ee L Ae 160 0 2 4 6 8 10 12 14 16 18 20 22 Frequency kHz Figure 48 Noise Shaping and Dither Spectra Spectra of 90dB 24 bit sinewave truncated to 16 bits with dither options dCS 972 SW v1 54 60 __ 24 bit source data 80 RE 16 bit truncation no dither 89 70 dB 16 bit truncated V 91 00 dB source signal m B f 2 SG w i S E dE S t S g d 1 z i 1200 cc 2 Q g Sa SS a b 2 SZ S E e SS 4 H SZ OF r G i I R G d i d ri av i K ry d Di 1 d t A p Po wh ms S j po whe LAS d A sve E k gt g d Ba l Ki es Ei a w I Pu g 140 e OS Ei K ia 1 ECH S L y Ze t K G ef D if og oe ZK os o sf i r x i i i d e s de t vu 2 c V V y Si 160 Aa E 3 AA i f ao A e A A N l Lull n Ane a i 12 14 0 2 4 6 8 10 16 18 20 22 Frequency kHz Figure 49 Truncation Only Spectra dCS 974 User Manual dCS Ltd Noise Power dB rel no shaping Manual for Software Version 1 0x May 2001 When is Dither Needed 30 24 24 30 36 42 48 Dither on its own or with noise shaping is not always needed The condition for not being needed depends on the level of noise in the incoming sign
47. ES 1 output It may be used to synchronise equipment connected to any of the dCs 974 data outputs The lower LOOP IN connector is intended for future enhancements Control and Power Remote 9 pin D type Female 2 off Remote In and Loop Out For remote control via a PC and or downloading software updates Remote In and Loop Out sockets allow daisy chaining of several different dCS units from one PC COM port Mains Supply 3 pin IEC CEE22 Switched fused and filtered IEC power inlet for a 50 or 60 Hz AC supply Additional Information As well as connectors the rear panel displays the following information about the unit near the mains supply connector Mains Voltage The actual voltage setting supplied Model Number dCS 974 Manufacturers Name and Country of origin dCS Ltd UK The underside of the unit will have a label on that contains a number such as 974 4B1 6B2 2A1 3A2 12345 This is the unit serial number but it also contains vital configuration information We will need this number all of it to give you support over the phone or to ship software updates to you dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Front Panel BIT OPERATION I Hax Status gam i Set ither Gees LIR flip MEMORY ee eca i ore er dCS 974 D to D Converter Figure 18 Front Panel Because of the many options on the dCS 974 we have used a menu based system to control it The hardw
48. Format Converter FC mode In SRC mode the unit performs DSP on the signal and gain is always reduced by 0 01dB This is because many of the other operations such as dithering or noise shaping add a small amplitude signal so we reduce the amplitude a small amount to prevent spurious Clips It also means that for simple operations such as Dual AES in to double speed AES out bits in will not be the same as bits out Because in some cases this is important the unit can also operate in FC mode FC mode has no 0dB signal drop and will not allow operations that can cause audio data bit changes but it does allow bit for bit copies of signals to be made in different digital formats It also allows message editing but many of the other options available in SRC mode are removed from the menus while FC mode is active SRC mode offers all the options of FC mode FC mode just turns off the options that affect bit for bit performance There are no options that are just available in FC mode Sample Rate Conversion The default setting is Sample Rate Conversion SRC mode on Format Conversion FC mode Off Pressing will open the Sample Rate Conversion menu Sample Rate Conversion RAaudio Input Select S0C Source Multirle Channel Sunc Input Sample Rate OULFUL Sample Rate Uutput Hode Filter dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Format Conversion The default setting is SRC mode on FC mode
49. If the unit is tested with sine waves at frequencies which divide almost exactly into the sample rate e g 6 001kHz signal 48 kS s sampling frequency the segments on the right hand side of the meter will flicker This effect disappears if the signal frequency is changed by about 10Hz and so it is not a problem when monitoring music It is caused by the signal beating with the sample rate dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 Display Submenu OOPS The final option on the top level menu is Display Select this and press gt isF lay Wir Okt E WE Conte ast RE Cursor Clockwise Down Backlight off after 1 min Bright adjusts the brightness of the display backlight and Contrast adjusts the LCD display contrast These should be set for optimum readability The length of the solid bars indicate the setting of each parameter there are 27 levels for each To adjust the brightness select Bright and press Set The cursor will change to the symbol Set the required brightness with the rotary control then press Set again to exit adjustment mode The Contrast is adjusted in a similar manner It is possible to turn the contrast to such a low setting that it is very difficult to read the display If this happens and the menu level is changed you may not be able to see the display well enough to navigate to the Display menu and increase the contrast to readable level To recover
50. NEN RER KENNEN R ERKENNEN RK 94 General Technical Information ccccccscceeeeeeeeeeeeeeeeeeeeeeeeeeneeenesenesenesenees 104 Word Length Reduction 104 Using Your dCS 974 For The First Time cccccceeceseeeeeeeeeeeeeeeeeeeeeeeeneeeenenes 110 What s in the Box 110 Supply Voltage Setting 110 Getting Started 110 Installing the Unit in a Rack 112 EE 114 Locking to Video Sample Rates 114 Mains Supply Voltage 114 Ordering Options for a New Unit 114 Having Your Options Changed 114 Maintenance and Suppolt ccccccsccsseceeeeeeeceesceeeeneeeneecesseneseneseneseneseneseeess 116 Hardware 116 Service amp Maintenance 116 User Changeable Parts 116 Software 117 Installing New Software 117 Warranty 118 Initial Warranty 118 Extended Warranty 118 Warranty Exclusions 118 Obtaining Service 118 Update or Calibration 119 Safety and Electrical Safety 119 WFOUDICSNOOUING SE 120 FAQs 120 If You Need More Help 123 Other Information 123 Indexes and Software Version NUMDEPG ccscceeeeeeeeeeeeeeneeeneseneseneeenes 124 Definitions of Units 124 Tables 124 Figures 125 Keywords and Phrases 126 Owner Registration Transfer 131 dCS 974 User Manual Manual for Software Version 1 0x dCS Ltd May 2001 Manual part no DOC1241121A1 Page 9 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual Manual
51. Off To turn FC mode on select Format Conversion and press The menu below will appear OMVeErS 1 OF BPoure Format Conversion OFF Audio Input Select Ser Source Multirle Channel Syric Ipgut SC Ee Rate Outeout Ho HES rR Edit Pressing Set will toggle the state from Off to On The unit will check to see if the Output Sample Rate is the same as the Inout Sample Rate and if it is not it asks you to press Set to change the Output Sample Rate or any other button to cancel the attempt to turn FC mode on BPure Format Conversion On Audio Input Select Sync Source Multiele Channel Sunc Input Se Rate ut gut Mo HES ME Edit On returning to the main menu Sample Rate Conversion is shown as disabled ate Conversion Ee Conversion Error Monitor Bit activity Moni tor Level Meters Disrelay To re enter SRC mode you have to set Pure Format Conversion to Off Error Monitoring Error monitoring on the input signal can be implemented for CRC Parity and Valid bits in the AES3 and SPDIF message streams This menu covers resetting the monitors and is only available for PCM inputs the entry disappears for DSD inputs Test The unit can be used as a very high purity signal generator as well as performing self test functions via this menu Info This menu displays information about the unit for support purposes dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Bit Activity Monitors
52. Reference Step 3 Setting a Conversion Format Conversion Sample Rate Conversion Step 4 Connecting the Outputs Connecting a Single AES or SPDIF Output Connecting the SDIF 2 Output Connecting the Dual AES Outputs Connecting the Quad AES or DSD Quad Outputs Connecting the DSD SDIF 2 or DSD SDIF 3 Output Step 5 Reducing the Output Wordlength Other Settings Converting a 24 96 recording to CD format Demultiplexing a 24 96 Dual AES recording Bit for Bit Upsampling a CD General Sample Rate Conversion and Distribution PCM to DSD Using a Master Clock Converting Quad AES to CD Format Multi channel Sample Rate Conversion bit aligned sources Multi channel Sample Rate Conversion Using a Master Clock Multi channel Sample Rate Conversion with more alignment tolerance Multi channel Sample Rate Conversion with multiple sample rates out Navigating through the Menu what the On Screen symbols mean Top Menu Sample Rate Conversion Format Conversion Error Monitoring Test Info Bit Activity Monitors Level Meters Display Sample Rate Conversion Format Conversion Submenu Audio Input Select Sync Source Multiple Channel Sync Input Sample Rate Output Sample Rate Output Mode Filter Output Word Length May 2001 dCS 974 User Manual dCs Ltd The Hardware Controls and Connectors dCS 974 Technical Information Manual for Software Version 1 0x Noise Shaping Dither AES Message Edit SPDIF Message Edit Gain
53. T would only give 13 9 dB perceived improvement less a further degradation from adding dither dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Manual part no DOC 1241121A1 Page 109 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 UsING YOUR dCS 974 FOR THE FIRST TIME What s in the Box The contents of the box are at least dCS 974 User Manual Quick Start Guide Power cable 2 Spare Fuses Remote cable Remote software Supply Voltage Setting The dCS 974 is shipped with its supply voltage preset for operation in the destination country The voltage is not intended to be changed by the user If it needs to be changed see the section Having Your Options Changed on page 114 Getting Started Here s what to do If the unit does not behave the first time you power up contact your re seller or dCS Check the appropriate mains supply for your local mains is marked on the rear panel If it is connect the unit to a power outlet using the cable supplied connect no other leads at this stage and switch on The Power LED wll light then the screen will light up and display Dats Conversion Systems After approximately 20 seconds the front panel LEDs will indicate the last stored state and the Unlocked LED wi
54. al the amount of noise shaping being used and the output word length The user may want to avoid having to think about this at all in which case use Noise Shaped Triangular dither or may wish to minimise noise and added noise As a rule of thumb if the following condition is met dither is not necessary Noise in input r Noise gain of 5 Q noise of wanted signal noise shaper output word length The noise gain of the noise shaper is the same as the unweighted noise power given in Table 16 and is shown in Figure 50 below Noise Gain and Weighted Noise Gain vs Shaper Order dCS 972 SW v1 54 Actual Increased Noise Power and Noise top section Gain o 96 kS s o 88 2 kS s m 48 kS s 44 1 kS s 532 kS s Perceived F Weighted Noise Power bottom section Noise Shaper Order Figure 50 Noise Gain and Weighted Noise Gain by Shaper Order and Sample Rate As an example of reading this consider a 24 bit signal in with a 110 dBO noise floor to be output at 48 kS s 16 bits The Q noise in the output signal would be 98 dBO so if a noise shaper with more 12 dB of noise gain was used no dither would be necessary Looking at the chart a 5 order shaper 14 2 dB of noise gain would avoid the need for dither whereas a 4 order one 10 9 dB of noise gain would need dither The 5 order shaper would give a weighted noise improvement of 16 4 dB whereas the A
55. al applications cccececeeeseeeeeeeeneeenees 22 typical spurious performance PCM ZA U units definition Be EE 124 Unlocked indicator nnnnnnnnnnnnnnnennennnnnnnnn 69 unlocking front pDanel 64 updating the software 117 upsampling a CD 24 upsampling CD to 24110 2 V VIGGO SVING erui a ten 114 W Waran y e deal set asain deeded a icuretecu sited 118 warranty exclusions cccceceeeeeeeeeeeee ees 118 warranty extended es 118 131 warranty Initial ccc eecceeeeeeeeeeeeeeeees 118 WIG IOI EE 92 WIGIMING BEE 84 weighting E 84 85 105 word length reduchon 104 Wordclock alonment 78 WOrdclock daisv cham 66 Wordclock In terminating ee 66 WOOrdeiocK INPUT arein 66 Wordclock Loop Out 66 VVOFGCIOCK e L I E 67 VV OFGGIOGK SYNG e EE 13 wordlength reducmg 19 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Manual part no DOC 1241121A1 Page 130 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 X Owner Registration Transfer To transfer the balance of the Extended Warranty to a new owner please complete the form below in block capitals and forward it with the Extended Warranty Certificate to dCS at the address below within 30 days of the sale dCs Ltd Mull House G
56. ample Rate kS s Time in Time in ns Time in ns input 44 1 kS s 96 kS s input input Basic dCS 974 unit to unit output timing alignment Input misalignment allowed with all inputs at the same frequency for block structuring to work no Master Clock Input misalignment allowed 668 324 with all inputs at the same frequency with Master Clock Input misalignment allowed 11338 5208 with all inputs at the same frequency with Master Clock as in Figure 16 Table 8 Multiple Channel Sync mode allowable input misalignment The scope shots below show the timing relationships between two units using the sync link for various conversions They are taken from 2 units with scope probes on the same point in each unit The units are linked by a sync link 19 version 2 0 software or higher Ul Unit Interval see AES3 spec There are 128 Ul s per sample in AES3 21 Master Clock can adjust its Wordclock phases as necessary dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Zoo running d 3 00 M 0Iy DN lim 56 250 10 00 1 ia de 2 5 00 Vrdiv af lim 6 000 EE ee Se ens Ged ee eR ih tee OR a So hie aces hp a EE EE E GE GE S HE WEE 1 0000 us 0 000 s 1 0000 us 200 ns div repetitive Trigger Mode Edge E 2 500 Figure 28 44 1 kS s to 96 kS s PCM showing AES3 alignment fe running 1 3 00 YWediv DN lim 56 250 VM 10 00 1 1M de e CH fee oe E i ey en I
57. anual for Software Version 1 0x dCs Ltd May 2001 Power Consumption The dCS 974 has a linear power supply and so power consumption changes as the supply voltage changes The internal regulation is comparatively efficient for a linear supply so these changes are kept to a minimum Consumption is independent of supply voltage setting Power Consumption with Supply Voltage measured as AC power into mains socket Nominal voltage 16 W Voltage 10 14 W Voltage 10 17 W The actual intended supply voltages are shown on the rear panel 50Hz or 60Hz operation is not important the unit can use either In general users will not need to change the mains input configuration If you do need this to be done please see the section Having Your Options Changed page 114 in this manual and contact your distributor or dCs dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 Size Weight and Operating Conditions Size and Weight The dCS 974 dimensions correspond to a standard 2U 19 rack mount case Four heavy duty feet fitted to the base extend the overall height to slightly greater than 2U Dimensions Width 430mm see note i Height without feet 88mm 2U Height with feet 95 mm Depth 390mm see note ii Weight 8 5kg see note iii note i Removable 19 rack mount ears are supplied taking total width to 483 mm 19 note ii Measured from front panel to rear panel connectors Additional depth sh
58. are buttons and knobs below navigate you through it Power Indicator The LED in the top left hand corner lights when power is applied OPERATION buttons The bank of 4 buttons in the top left hand corner are the Operation buttons and are used for navigating around the menu tree Status returns the display to the status information screen to allow a rapid check of key settings e selects the previous higher menu level gt selects the next lower menu level Set implements the selected menu item MEMORY buttons The bank of 4 buttons in the lower left hand corner are the Memory buttons and are used for storing and retrieving setups Recall allows one of ten stored setups to be selected ready for loading Store allows one of ten locations to be selected as the location for saving the current setup Edit is used to change the name of a saved setup Enter loads or saves a setup LCD display The backlit LCD display in the centre of the panel can display up to 8 lines of information dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 LED indicators A group of LED indicators to the right of the LCD display gives a level of status indication Dither is lit if any Dither is selected Noise shaping is lit if any Noise Shaping is selected L R flip indicates that the channels are flipped Two Phase LEDs indicate if either or both channels are phase inverted Gain is lit if the setting is other than uni
59. ary control will move the cursor up and down the list Now press the Set button to accept Gain and the cursor changes to to indicate that this parameter Gain may now be adjusted using the rotary control Turn the control either way and the Gain changes in 0 1dB steps When the required setting is reached press Set and the cursor will change back to W Pressing lt when the cursor is For W returns to the previous menu level Pressing Set when the cursor is W and the option cannot be adjusted e g AES 1 in the Audio Input Select menu selects that option and returns to the previous menu level From the Status screen pressing any of the four Operation buttons displays the last menu level used Pressing the Status button when the cursor is bk or m displays the Status screen for the selected menu dCS 974 User Manual dCs Ltd Top Menu Manual for Software Version 1 0x May 2001 The top menu contains the major entries Sample Rate Conversion Format Conversion Error Monitoring Test Info Bit Activity Monitors Level Meters and Display as follows Oper SLOPn Format Conversion Error Monitor Test Into Bit Activity Monitor Level Meters sp lau In many cases the settings in one menu do not affect those in others In other cases they do and where this occurs the menu will automatically adjust to allow only valid options The unit can operate in one of two main modes Sample Rate Converter SRC mode and
60. at a time when only 3 sample rates were in common use in the audio industry dCS started manufacture of ADCs featuring 96 and 88 2 kS s sample rates in 1993 and we have evolved modifications to AES3 1992 which accommodate these innovations These are currently being considered by the AES The AES EBU interface transmits a data structure that conforms to the dCs version of AES3 1992 This contains 28 bits of Manchester encoded data and a 4 bit near Manchester encoded preamble in a subframe and subframes are further assembled in a block and frame structure Each subframe contains e preambles to allow the receiver to sync up e up to 24 bits of audio data transmitted Isb first e V a validity bit e U auser bit for the User Message e C a Channel Status bit for the System Message e P a parity bit IMPORTANT The AES EBU interface and the SPDIF interface have similar data structures although the messages are completely different The two structures are identified in the data domain by the use of the Consumer Professional bit bit 1 in the message A I indicates AES EBU format a 0 indicates SPDIF format The default AES EBU message attached to the output data by the unit before being changed by the user is as follows Professional On Non Audio Off Mode Stereophonic Source DCS1 Destination null For more information on the way dCS implement the AES3 system message to handle higher sample rates see the Appendix to this man
61. ator operating at a sample rate of 705 6 kS s and then converted to DSD This means that the maximum frequency that it can produce is 352 8 kHz dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 To set up the generator press twice to move to the menu screen then display the Test menu BGenerator Sine Generator Amel itiude IS DOE Generator Freswency H S999kHz Self Test The Generator options are Off Sine and Square Press Set slowly to scroll through these There is a short delay while the generator code Is loaded IMPORTANT The initial Generator Amplitude is 18dB0 If the dCS 974 is ultimately driving speakers or headphones ensure the system gain is at a reasonable level before turning the generator on Generator Amplitude Adjustment Select Generator Amplitude and press Set to adjust it Turn the rotary control counter clockwise to reduce the amplitude in 0 5dB steps or clockwise to increase it Attempting to increase the amplitude above OdB causes the setting to wrap around to 120dB When the required amplitude is displayed press Set again to update the setting Generator Frequency Adjustment Select Generator Frequency and press Set to adjust it The following screen appears JP d SIS l Fresauerncy EE VW E The frequency resolution of the generator is about 1 part in 2 of the sample rate about 10uHz at 48 kS s Rotating the knob moves the arrows left and right When the
62. aximum gain that may be applied is 12dB If the correction exceeds this 12 0dB of gain will be applied Please note that Maximise cannot correct overloads Maximise can be run repeatedly if you have a lot of gain to max up At the start of the track select Maximise then Reset max hold and press Set At the end of the track select Maximise then Maximise and press Set The gain correction will be applied Replay the track and the gain will be Maximised Select Maximise then Disolay max hold and press Set to see the current peak signal record Fle Fate Lonversion Gap Channels EHormal SwWaAFFed This allows the left and right channels to be swapped For normal operation select Normal and press Set To swap channels select Swapped and press Set the L R Flip LED will light up The options for Phase are Normal Select then press Set Outputs are in phase with inputs Both Phase indicators are off Left Inverted Select then press Set Left channel is out of phase with input Right is in phase Left Phase indicator lights Right Inverted Select then press Set Right channel is out of phase with input Left is in phase Right Phase indicator lights Both Inverted Select then press Set Both channel outputs are out of phase with inputs Both Phase indicators light dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Detect Silence Detect Silence is a PCM only option that gives digital silence out if th
63. ces below It actually uses an Error Shaping architecture but the name is now being used for entirely other things and is less well known so we call it erroneously Noise Shaping Ss Minimally Audible Noise Shaping S P Lipshitz and R A Wannamaker J AES vol 39 no 11 p836 852 i Psychacoustically Optimal Noise Shaping R A Wannamaker J AES vol 40 no 7 8 p611 620 dCS 974 User Manual dCs Ltd Dither Manual for Software Version 1 0x May 2001 The dCS 974 uses relatively unusual dither generators to achieve the very good Statistics necessary for audio purposes Many dither generators use PRBS generators Pseudo Random Binary Shift register generators These are well known well documented and very predictable but unfortunately their statistics are not that great The problem shows up as a spectrum that is not flat and histograms PDFs Probability Density Functions that diverge from the ideal quite significantly Adding dither adds noise Top hat dither uses one generator per channel to add 0 5 Isbs p p of rectangularly distributed dither and triangular dither uses two generators per channel to add 1 Isbs p p of triangularly distributed dither This is on top of the Q V12 rms dither from word length reduction in the first place where Q is the size of the output word Isb The noise shaped triangular setting uses one generator to add 1 Isbs p p of triangularly distributed dither that is frequency shaped and so has
64. cibels referred to the defined full scale sine wave in a DSD system So 0 dBOpsp is the zero dB audio reference level dBu Level in decibels referred to a 0 775V rms sine wave with no external loading u unloaded The level of 0 775V is derived from the older dBm for which the reference level is 1mW of signal power into a 600Q termination from an output with 600Q source impedance kS s Sample rate in kilo samples per second This replaces kHz which is technically incorrect when referring to sample rates SQNR Signal to Q noise ratio Table 1 Menu Tree 35 Table 2 One Pass and Two Pass Conversaions 44 Table 3 Conversions with Multiple Filter Options cccccecceeeeeeeeeeeeeees 46 Table A DSD Filter Summary 71 Table 5 DSD Filter Performances ccccccccsecceeeceeeeseeeseeeeeeeeeeseeeseeeseeeeeees 72 Table 6 Typical Spurious Level VS Conversion s nsenseneennernennenrnnrrnrrnrnne 74 Table 7 Group Delays PCM to PCM transitions annannannannnnnnnnnnnnnnnnnnnnn 75 Table 8 Multiple Channel Sync mode allowable input misalignment 81 Table 9 Noise Shape Orders by Output Sample Rate annnannnannannnennnannn 84 Table 10 Noise Added by Dither Tvpes 85 Table 11 AES EBU Interface Electrical Characteristics ccccsecceeeeeees 86 Table 12 DSD SDIF Interface Electrical Characteristics cccceeeeeeeee
65. d AES The Inout amp Output Sample Rate must be 176 4 or 192kS s Quad AES bit for bit data will be available on the AES 1 AES 2 AES 3 and AES 4 output group Do not use the other outputs e DSD SDIF 2 The Audio Input Select setting must be DSD or DSD Quad DSD SDIF 2 bit for bit data will be available from the DSD SDIF outputs lower block and DSD Quad data from the AES 1 AES 2 AES 3 and AES 4 output group Do not use the other outputs e DSD SDIF 3 The Audio Input Select setting must be DSD or DSD Quad DSD SDIF 3 bit for bit data will be available from the DSD SDIF outputs lower block and DSD Quad data from the AES 1 AES 2 AES 3 and AES 4 output group Do not use the other outputs Proceed to Step 4 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Sample Rate Conversion TOP LEVEL Sample Rate Conversion Audio Input Select 192kS s 176 4kS s Multi Channel Sync I eS Input Sample Rate 12kS s Output Sample Rate 11 025kS s Default DSD SDIF 3 Figure 4 Sample Rate Conversion lf DSD output formats are required proceed to Setting the Output Mode Setting the Output Sample Rate If PCM outputs are required scroll down the Sample Rate Conversion menu to Output Sample Rate and press the button Scroll down the list to the required rate and press the Set button If the selected conversion can be handled in one pass the setting will be accepted and the scr
66. d May 2001 Multi channel Sample Rate Conversion with more alignment tolerance WORDCLOCKS TO SOURCES dCS 992 Master Clock ei Q Mains Fuse 2AT On Off oa e Ge e OO 96kS s Ch1 amp 2 lE N AOD r FROM SOURCE 96kS s Ch3 amp 4 SOF 96kS s Ch5 amp 6 i FROM Be SOURCE S 96kS s Ch7 amp 8 Figure 15 Multi channel Sample Rate Conversion with more alignment tolerance A dCS 992 Master Clock can also be used to sync the source and the dCS 974 units as above In addition to the sync link cabling starting with AL additional clocking cables C allow the dCS 974 s to extract clocks from the C cables and extract the data from the signal input cables The master clock outputs different frequencies on the different cabling types This allows considerable bit alignment error as might occur if some tracks are stored on one machine and some on another For all dCS 974 units set the Sync Source to Wordclock and the Multiple Channel Sync option to On They will all set up as slaves Make sure that all the other settings are the same on each unit Note that cable A must NOT be driven from the dCS 992 s AES1 output version 2 0 or higher software dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Multi channel Sample Rate Conversion with multiple sample rates out A dCS 992 Master Clock can also be used to sync up the source and more than one set of units all a
67. dCs Ltd May 2001 Amplitude dB Amplitude Isb 24 Dither Only Spectra no Signal dCS 972 SW v1 54 110 Aw Ver ew minted pits pala ell P sl INI Top Hat dither actual theoretical SEH Triangular dither actual theoretical Noise Shaped Triangular dither actual theoretical 140 150 0 2 4 6 8 10 12 14 16 18 20 22 Frequency kHz Figure 32 Dither Spectra FFTs Raw Data for Source and Truncated Small Signal dCS 972 SW v1 54 2048 1024 A OT _ mas WW UTI Wu Wi K Wl Ui IN I re i II Mi Bd UNE uh JN yoo Ei 1 WI Vi WI TT HN ut Mu IE d 1024 24 bit source data 16 bit truncation 16 bit truncation with Top Hat dither 16 bit truncation with Triangular dither 16 bit truncation with Noise Shaped Triangular dither 2048 0 128 256 384 512 Sample Number Figure 33 Small Signal Raw Data with Dithers dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Spectra of 90dB 24 bit sinewave truncated to 16 bits with dither options dCS 972 SW v1 54 60 24 bit source data TEREPE 16 bit truncation no dither 16 bit truncation Top Hat dither 80 16 bit truncation Triangular dither 16 bit truncation Noise Shaped Triangular dither 100 Amplitude dB 120 140 Zo PAS lee oe not NA tea wa Wen Aah Ju IA A 4 0 2 4 6 8 10 12 1 16 18 20 22 Frequency kHz Figure 34 Truncated small
68. distortion Spurs P are caused by high order images of the baseband input signal aliasing back into the output The filtering in the converter has to suppress these We measure these spurs for a 1 kHz input signal typical values are given in dBO for a 1dBO sine wave in the table below The blank cells are two pass conversions where the performance depends on both conversions Output Sample Rate kS s 22 05 24 32 44 1 48 96 176 4 192 134 134 109 132 119 130 132 121 117 105 139 117 Table 6 Typical Spurious Level vs Conversion Ke Spurious products For example a 1 kHz tone with a 48 kS s sample rate in will produce spurs at 2 9 KHz and 4 9 kHz 6 8 kHz and 8 8 kHz etc with a 44 1 kS s sample rate out dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Noise Noise arises from processing rounding errors and from stop band performance It is typically around 130dB0O but depends on the conversion being used Group Delay The conversion process takes time and the time is dependent on the conversion being carried out and the filters used Typical values in microseconds are given for four conversions in the table below Group Delay us Sample Period us Conversion Filter Filter Filter Filter Input Output 1 2 3 4 44 1k gt 96k 1141 1131 1131 1131 22 676 88 2k 44 1k 1024 11 338 96k 44 1k 1515 1065 1065 1065 10 417 96k 48k 868 958 1028 948 10 417 Table
69. e DSD DSD Quad or PCM at 44 1kS s or more DSD SDIF 2 data will be available from the DSD SDIF outputs lower block and DSD Quad data from the AES 1 AES 2 AES 3 and AES 4 output group Do not use the other outputs Proceed to Step 4 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Step 4 Connecting the Outputs Choose one of the following five sections Connecting a Single AES or SPDIF Output If the Output Sample Rate is 88 2 or 96kS s check that your destination equipment is capable of double speed operation If you have set Output Mode to Normal connect the required single wire output on the dCS 974 rear panel to the matching inputs on the destination equipment using suitable cables Signals are available from any of the four AES EBU outputs or the three SPDIF outputs simultaneously Connecting the SDIF 2 Output If the Output Sample Rate is 88 2 or 96kS s check that your destination equipment is capable of double speed operation If you have set Output Mode to Normal connect the lower block of DSD SDIF connectors on the dCS 974 rear panel to the destination equipment using 3 coax cables Connect CH1 OUT to CH1 in CH2 OUT to CH2 in and WCLK OUT to CLK in Connecting the Dual AES Outputs Check that your destination equipment is capable of Dual AES operation If you have set Output Mode to Dua AES connect the AES 1 output on the dCS 974 rear panel to the AES 1 or AES A input on the destination equipmen
70. e of 44 1 kS s or 48 kS s as the intermediate sample rate so you can record the intermediate pass on most recording devices However it is best to use the highest possible sample rate for the intermediate pass if your recording device can take it For example to convert from 192 kS s to 12 kS s first convert from 192 kS s to 96 kS s and then convert from 96 kS s to 12 kS s Use of two dCS 974 s avoids intermediate storage For DSD output select DSD SDIF 2 or DSD SDIF 3 and the unit will make the appropriate changes The unit supports DSD out with either DSD or PCM in DSD output includes a DSD DC blocking filter All signals in DSD or PCM will have their DC filtered out When set to either DSD output mode a DSD Quad signal appears on four output cables AES 1 AES 2 AES 3 and AES A The 3 SPDIF outputs all carry identical AES streams with no data they may be used for synchronisation For PCM output select Dual AES to output a 192kS s 176 4kS s 96 kS s or 88 2 kS s AES3 signal on two output cables AES 1 and AES 2 or AES 3 and AES 4 In this mode the AES Clk Output and 3 SPDIF outputs all carry identical AES streams with no data they may be used for synchronisation The SDIF Clk Output sends Wordclock at the same rate as on AES 1 do not use the SDIF data outputs while in Dual AES mode For PCM output select Quad AES to output a 192kS s or 176 4kS s AES3 signal on four output cables AES 1 AES 2 AES 3 and AES 4 In
71. e unit detects digital silence in This is useful where dither and or noise shaped truncation are being used without it even if the signal in goes to digital silence the output will continue to output low level noise It allows some automation further along the CD preparation chain The options are On Select then press Set Output goes silent after about 25ms_ of silence in Output recovers immediately when the input goes live although it takes about 25 ms for the dither to turn back on if this is used Off Select then press Set IMPORTANT Digital Silence detection does not currently operate in DSD modes De Pre Emphasis For Output Sample Rates of 32kS s to 96kS s Emphasis may be applied or removed using this menu The menu displays E OnVers Lor Hes Pre SE Bit De Emehasis 5671 Auer De EmehasistClITT TI Pre Enrhasis Se 15sec Pre Emehasis CCITT J 1r Select the appropriate function and press Set IMPORTANT Note that the unit drops the signal level by 12dB when applying pre emphasis to prevent overloads occurring When removing pre emphasis de emphasising there is no signal drop When units are run back to back therefore in any order applying and removing pre emphasis there will always be a 12 dB signal drop Display Customise This menu allows the user to determine which five parameters are displayed on the status screen in addition to input and output sample rates The active parameters in the
72. ed and multiple units may be synchronised for stable multi channel operation The unit is mains powered and is housed in a 2U 3 5 high 19 rack mounting case It may be controlled either from its front panel or from a software based remote control running on a PC Frequently used Setups may be stored and re called later The last setting is automatically stored on power down so that fixed installations may be set up at leisure installed and then left alone Unauthorised alterations to settings may be prevented by a panel lock out feature Numerous monitoring functions are provided both for the audio signal and for messaging attached to it The unit has bit activity and level meters and message manipulation CRC parity and invalid errors may be monitored and reported so that right first time transfer to disc plants may easily be achieved The unit is highly software based and more functions and features are added from time to time Software updates from dCS are free e DSD at 2 822MS s see page 71 e PCM from 192 kS s down to 11 025 kS s see page 43 e PCM data formats supported are AES EBU XLR Dual 2 wire AES3 XLR Quad 4 wire AES3 XLR SPDIF Phono Toslink and BNC and SDIF 2 see page 70 e DSD data formats supported are SDIF 2 BNC SDIF 3 BNC and DSD Quad 4 wire XLR Sample Rate and Format Conversion page 34 Multi channel Sync capability page 42 Bit for bit multiplex de multipl
73. ediate combination that cannot be handled in one pass Press Set and choose a valid Nout or Output Sample Rate as appropriate from the list The Customise Display menu will not allow another option to be set e f you check the list you should find that the maximum of 5 parameters are already marked with a X Remove one you do not need and try again dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 If You Need More Help Contact dCS Our office hours are 8 00 a m to 5 00 p m Monday to Friday UK time UTC or UTC 1hr Contact us by phone or fax on Inside the UK Outside the UK Telephone 01799 531 999 44 1799 531 999 Fax 01799 531 681 44 1799 531 681 Table 18 dCS Phone Numbers You can write to us at dCs Ltd Mull House Great Chesterford Court Great Chesterford Saffron Walden CB10 1PF UK Our E Mail address more dcsltd co uk Our web site is http www dcsitd co uk Other Information dCS produce technical notes from time to time If you are interested in these please do not hesitate to contact us or check our web site dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 INDEXES AND SOFTWARE VERSION NUMBERS This manual is for software version 1 0x v1 0x versions differ only in a few minor bug fixes Definitions of Units Tables dBo Level in decibels referred to a full scale sine wave in a sampled system So 0 dBO is full scale dBOpsp Level in de
74. een will change back to the Sample Rate Conversion menu If not this information box will appear on the display 441 Ao CES ch Invalid Fs In for Fs Out Press a key to alter Fs Out H S Filter Cut 1 Bali L HdE KR db Press any button to display a list of valid output sample rates Scroll down the list to a suitable rate and press the Set button dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 Setting the Output mode Scroll down the Sample Rate Conversion menu to Output Mode and press the button The cursor should be beside Norma Choose one of the settings from the following list scroll to it and press Set Normal The Output Sample Rate must not be higher than 96kS s Single wire data will be available on all of the AES SPDIF or SDIF 2 outputs Dual AES The Output Sample Rate must be 88 2 96 176 4 or 192kS s Dual AES data will be available on the AES 1 AES 2 output pair and the AES 3 AES 4 output pair Do not use the other outputs Quad AES The Output Sample Rate must be 176 4 or 192kS s Quad AES data will be available on the AES 1 AES 2 AES 3 and AES 4 output group Do not use the other outputs DSD SDIF 2 The input format must be DSD DSD Quad or PCM at 44 1kS s or more DSD SDIF 2 data will be available from the DSD SDIF outputs lower block and DSD Quad data from the AES 1 AES 2 AES 3 and AES 4 output group Do not use the other outputs DSD SDIF 3 The input format must b
75. er and press Set For 16 or 17 bits scroll down the Sample Rate Conversion menu to Dither and press the gt button Scroll down to NS Triangular and press Set dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 A wide variety of Noise Shaping and Dither setting combinations are possible For more information see Word Length Reduction on page 104 Proceed to Other Settings dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Other Settings The basic set up procedure is complete The Sample Rate Conversion menu contains several other menu pages For more information see Sample Rate Conversion Format Conversion Submenu starting on page 41 dCS 974 User Manual dCs Ltd TYPICAL APPLICATIONS Manual for Software Version 1 0x May 2001 Converting a 24 96 recording to CD format From 24 bit 96kS s source DC EBU D O e LOOP CLK OUT SYNC INPUT 6 AHS EBU OUTP TS 16 bit 44 1kS s from SPDIF CH AEE CH2 IN REMOTE Ce S Sg SE DZ OUT CH1 OUT CH2 OUT DSD SDIF bai f OO 16 bit 44 1kS s 16 bit 44 1kS s 4 independent AES outputs from 3 independent SDIF 2 output SPDIF outputs Figure 6 Double Speed 24 96 to CD format The dCS 974 converts a double speed 96 kS s 24 bit AES input to a 44 1 kS s 16 bit signal available from all of the 4 AES 2 electrical SPDIF optical SPDIF or SDIF 2 outputs The conversion set up uses
76. es 86 Table 13 SPDIF Interface Electrical Characteristics ccccccecccseeeeeeeeees 86 Table 14 SPDIF Optical Interface Characteristics ccccccccccceeeeeeeeeeeeaees 87 Table 15 SDIF 2 Message Table cccccsecccsseeceeeeceeecececeeeeseeeeeeeseeeseas 90 Table 16 Dither and Noise Shaping Noise Powers nannnennnnnnennnnnnnnnnnnnn 105 Table 17 Options available EE 114 Table 18 dCS Phone Number 123 dCS 974 User Manual dCS Ltd Figures Manual for Software Version 1 0x May 2001 Figure 1 Audio Input Selection srnu a N a 11 Figure 2 Syne Source Gelechon ia n aaa iaa a 13 Figure 3 Pure Format Conversion ccccccccseccseeeeeeeeseeeeseeeeseeeeseeeeseeesaeeees 15 Figure 4 Sample Rate Conversion cccccssccceseeceeeeceeeeeseeceuseseueesseesseeesaas 16 Figure 5 Setting Wordlength Noise Shaping and Dither a0nnnann0nnn0annaannn 19 Figure 6 Double Speed 24 96 to CD Tomat 22 Figure 7 Converting dual AES 24 96 to a single wire double speed one 23 Figure 8 Upsampling a CD to 24 96 or 24102 24 Figure 9 General Sample Rate Conversion cccscccceseeeeeeeeeeeeeeeeseneeesaees 25 Figure 10 PCM to DSD conversion cccceseeceeeeceeeceeecceeceuseseuseseeeeneeesees 26 Figure 11 Using a Master Clock A 27 Figure 12 Converting Quad AES to CD format cc ceccecseeeeeeeeeseeeeeneeees
77. ex mode page 39 PCM to DSD DSD to PCM DC Removal for DSD Multiple filters on many major sample rate conversions page 45 Dither 3 types see page 47 Noise shaping 10 different options on all major PCM sample rates page 47 Output Level control with Maximise page 48 e Balance control page 48 e Digital Silence out with digital silence in page 50 Comprehensive can sync to Wordclock or AES reference or signal and sync to video option available free if we email them and you download from a PC COM port Low cost if you ask us for ERROMs or other media we charge for media and handling dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Monitoring Bit Activity page 56 Stereo Output Level page 57 and CRC Parity amp Invalid flag errors in the input data page 52 Test Generator High quality 160 dB signal generator with mHz resolution page 53 Can be dithered and or noise shaped truncated Ease of Use User programmable set ups page 61 Pre loaded setups Remembers last settings Lockouts page 64 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 About this Manual If you have not used a dCS 974 before please read the section Using Your dCS 974 For The First Time on page 110 This manual has been arranged with the most commonly used sections placed first table of contents page 6 step by step page 10 and applications guides
78. ficate for this unit within 30 days of purchase please note the serial number on the underside of the unit and contact dCs Registration ensures you will receive information on important hardware and software upgrades as they become available If you sell the unit within the first year the balance of the Extended Warranty may be transferred to the new owner by completing the Owner Registration Transfer form page 131 and returning it with the Extended Warranty Certificate to dCs The Warranty on this dCS 974 shall be void if e the product is misused in any way e any unauthorised modifications or repairs are carried out e the product is not used in accordance with the Operating Conditions stated on page 92 of this manual e the product is serviced or repaired except by an authorised dCS Distributor e the product is operated in a system without a mains earth or ground connection e the unit is returned inadequately packed If you experience problems with your dCS 974 you should check the Troubleshooting section on page 120 You may be able to resolve the situation yourself for example by changing a menu setting lf this does not resolve the problem contact your local authorised dCs Distributor for advice quoting the model the serial number from the underside of the unit the software version number see the Info Submenu page 56 and giving a detailed description of the fault Please do not return any unit to dCs witho
79. g that is optimised to the F weighting curve It does not affect signal frequency or transient response but shapes the frequency response of errors Q noise or truncation errors so that they fall as much as possible in the less sensitive part of the spectrum The architecture used also shapes dither where this is added For all the major sample rates 32 kS s 44 1 kS s 48 kS s 88 2 kS s 96 kS s the noise shapers have been individually optimised and the first 10 orders are offered The 1 3 and 9 shapes for 44 1 kS s agree well with Wannamaker s published results Noise Shaping adds more noise power but because of the shaping it is perceived as lower noise There is a compromise to be drawn as more aggressive shaping is used more noise is added and less perceived improvement occurs In practice things stop improving by about the 10 order The increased real noise power can cause small clicks in editing if this is carried out after the shaping For each major sample rate we recommend an aggressive and a gentle setting below Sample Rate Lowest Highest Gentle Aggressive kS s Order Shaping Shaping 39 43 10 gnd gin 44 1 1 10 ST g 48 43 10 gnd CW 88 2 e 10 3 a 96 43 10 gra 7 Table 9 Noise Shape Orders by Output Sample Rate The gentle shaping tends to follow the E weighting curve by chance For more information on this topic either see Word Length Reduction on page 104 or read the referen
80. hanges and then it decays into distorted mush and either abruptly stops or else keeps fuzzing away until a new signal starts The level at which all this happens is the Isb of the output word for CDs it is at the 16 bit level which equates to about 90 dBO The level is high enough to be quite audible and the effect must be tackled to make reasonable quality CDs There is really only one way of tackling the problem another signal has to be added to the wanted one to smooth the staircase transfer function that truncation causes Mathematically with two signals present the transfer function the wanted signal sees is the convolution of the PDF of the second signal and the staircase function The converse is also true the transfer function the additional signal sees is the convolution of the PDF of the wanted signal and the staircase function This aspect is not a problem with the dither types considered below but it can be with some highly frequency shaped dithers The additional signal is usually referred to as dither and it is usually noise like because then its statistics can be controlled and the converse effect of the signal modulating the dither can be made insignificant or zero However there are a number of ways that this dither signal can be generated and treated The major options are e it can be generated from the signal or generated independently and added Dither It seems implausible that the dither sig
81. he dCS 974 7 384 Dither PDFs showing how the dither types are effectively ideal including noise shaped triangular dither FFTs of the dither signals used excludes truncation or Q noise Raw data for small signal truncated 4 Isbs sinewave showing source waveform no dither and all dither types Shows absence of DC offset and behaviour of the various dithers FFTs of truncated small signal 90 dBO sine showing no truncation truncation without dither and the effect of dithers FFTs of truncated small signal 90 dBO sine with noise shaping with and without added dithers DSD spot Q noise for filter options DSD integrated Q noise for filter options DSD F weighted Q noise for filter options DSD 0 dBO full scale signal 48 kS s to 44 1 kS s conversion Filter responses 96 kS s to 44 1 kS s conversion Filter responses Noise shaping curves for 32 kS s Noise shaping curves for 44 1 kS s Noise shaping curves for 48 kS s Noise shaping curves for 88 2 kS s Noise shaping curves for 96 kS s Noise Shaper noise and weighted noise vs shaper order Histograms of Dither Types before Truncation dCS 972 SW v1 54 pple yy A A V IW EA La Al A Mf wy K wl wy ae ch A Top Hat Triangular Noise Shaped Triangular 128 0 128 256 384 Code Isbs Figure 31 Dither PDFs 27 Note that many aspects of the dCS 974 are identical to those of the dCS 972 dCS 974 User Manual Manual for Software Version 1 0x
82. igure 47 Noise shaper noise and weighted noise vs order Order 1 Order o Order 3 Order 4 Order 5 Order 6 oe Order 7 Order 8 Order 9 Order 10 44 48 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Manual part no DOC 1241121A1 Page 103 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 GENERAL TECHNICAL INFORMATION Word Length Reduction Word length reduction truncation causes an error signal to be added to the wanted signal The error signal is usually referred to as Q noise or Quantisation noise the approximation is made that the errors are noise like This is true for large signals but for smaller ones it is not so As the wanted signal gets smaller the complexity of the error signal decreases and the errors first of all pile into ever lower order harmonics or intermods and then as the level of the signal sinks below the Q level much error power piles into the fundamental This causes its amplitude to become unpredictable it may drop abruptly to zero and disappear or it may cease to go down any more and just stay at a constant level From the audio viewpoint this sounds very unpleasant As a Signal tail decays away the tonal quality c
83. ilable sync sources are Audio Input Syncs to the selected input source this is the normal setting AES Loop Syncs to the AES Ref Loop In leaving the reference unterminated to allow daisy chain connection through Loop Out to another device AES Loop Term Syncs to the AES Ref Loop In and terminates the reference source Wordclock Syncs to DSD SDIF WCLK IN in the upper group of connectors Internal syncs to the dCS 974 s internal clock Lab Ref Syncs to a 10 MHz signal into DSD SDIF CLK IN in the upper group of connectors For best results synchronise to the Audio Input or a master clock on one of the clock reference inputs that is also driving the source For DSD SDIF inputs you can still sync to Audio Inout as the unit will automatically sync to DSD SDIF WCLK IN For DSD in SDIF 2 or SDIF 3 mode a Wordclock must be used contact dCs if you need a Bit Clock The Lab Ref setting allows use of a GPS reference if you use this make sure other parts of your system are also GPS syncd Only select Infernal sync if you are using the unit as a signal generator or a reference clock source dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Multiple Channel Sync This option is either On or Off at le Fate Lonversion a Channel Sync E r The unit uses the AES Ref Loop In as a sync link When On if the unit detects a sync signal into the AES Ref Loop In it will sync to it and set up as a
84. is a DSD generator If the unit is sync d to an input when it goes into Generator mode then the generator stays sync d to that input so the output will be synchronous and locked If the unit is not sync d to anything set the Sync Source to Internal Otherwise the equipment you are trying to drive may be unable to lock to the Generator outputs because the sample rate has drifted out of lock range The Sample Rate Conversion menu is still active in Generator mode so it can enter Generator mode with no external syncing the Generator can be set up a sync input can be selected from the Sample Rate Conversion menu and the unit will sync to that Noise shaping and other features available in the Sample Rate Conversion menu can still be used as long as these operate at the output rate Fillers for example do not affect the generator output because they operate on the input signal Dither operates at the output rate so it can be used Controlling the Generator 10 To view the Test Mode screen go to the top level menu select Test and press Status to get the display below assumes 96kS s sync source Irn 9 Buses Out 44 1 ks Waveform Generator OFF AmMelitude 185 Frequency 1 006k Hz If the unit is set to Internal sync the screen will show Int beside the input sample rate as follows tnt Bisvs Lut 44 1 kS s Waveform Generator Sine AMelitude 16 Fresuency 1 HggkHz in DSD mode it is a PCM gener
85. l The Generator is turned off and reset to 18 0dB 1kHz at power down The last option on the test menu is Self Test this exercises the LEDs and the LCD display Select this and press Set If all is well the LEDs will flash in sequence and the LCD will display a pattern of flashing columns Press any button to exit from this dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Info Submenu To display information about the unit return to the top level menu select Info and press Set The Info screen will be displayed Front Panel EEPROM ul Rp Control Board EEPROM wl Rp Control Board SH 10002 546 061 624 dS email gcsddcadcsltgd co uk FCH Conversions Surrorted 98 Conversions with gt 1 filter 43 The first three lines give important details about the hardware and software installed in your dCS 974 This is helpful if you experience difficulties with your unit Line four is dCS E mail address for use if you need any further assistance The last two lines give you a hint of the options available on your machine Bit Activity Monitor Submenu Bit Activity Monitoring Overview This monitors activity on the selected input and indicates the wordlength of the data provided by the source device Because the monitor works on the input it can be used for DSD outputs if the input is PCM To monitor the PCM output use Level Meters instead Setting the Monitor To access the monitor return to the top le
86. ld be aware of what it does To set the gain select Gain then press Set Turn the rotary control to adjust the Gain anywhere between 100 0 dB and 12 0 dB in 0 1 dB steps Press Set again to exit 9 The dCS 974 has a global gain of 0 01 dB absolute so when the unit says 0 dB the overall gain will be 0 01 dB This is because noise shaping dither and a few other mechanisms can add small amounts to an input signal but enough to cause digital clipping The 0 01 dB global gain shift avoids the problem dCS 974 User Manual dCs Ltd IMPORTANT Swap Channels Phase Manual for Software Version 1 0x May 2001 Use positive gain with care as the unit does not monitor overloads If in doubt use Maximise instead With Balance set central i e L OdB R OdB no gain is applied to either channel Panning to the right attenuates the left but does not amplify the right channel and vice versa This arrangement helps avoid overloads To set the balance select Balance then press Set Turn the rotary control to adjust the balance anywhere between 0 0 and 6 0qB on either channel in 0 2dB steps Adjustment beyond 6 0dB mutes that channel Press Set again to exit Maximise is a feature that makes best use of the available dynamic range The dCS 974 keeps a running record of the maximum amplitude of the signal Maximise can then apply the exact gain to ensure the highest signal peak noted is boosted to full scale The m
87. level If there are no more submenus it changes to W Turn the rotary control clockwise and the cursor will move down the list Turn the rotary control counter clockwise and the cursor will move back up To access the Sample Rate Conversion menu set the cursor adjacent to Sample Rate Conversion and press the gt button The screen will change to G t le Rate Conversion Reaudia Inreut Select Sync Source Hultirle Channel Sync Input Samele Fate Quteut Sample Rate QuUteut Mode Filter The cursor shape is still because the option selected has a lower level The symbol in the lower right hand corner indicates that there are more options available than can be displayed Use the rotary control to move the cursor down the list When the cursor reaches the bottom of the screen the list will scroll upwards and a T appear in the upper right hand corner to indicate that there are more options above When the bottom of the list is reached the symbol disappears The screen displays OnVvers lor der Hessade Edit Gain Balance Gap Channels Phase Detect Silence De Pre EmrPhasis BOisrelay Customise Move the cursor back up to Balance Gain and press the button to display the bottom level DNES Lor Ee BGsin 6 4HdB Bal Lo OD Ep odp Haximise dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 The cursor has changed to W to indicate that the bottom level has been reached Turning the rot
88. litude relative to No Shaping dB Noise Amplitude relative to No Shaping dB 18 2nd or 8th Order Recommended 36 0 4 8 12 16 20 Frequency kHz Figure 44 48 kS s noise shaper curves 88 2 kS s Noise Shape Plots dCS 972 SW v1 54 36 30 24 18 12 Ge SE 6 Manual for Software Version 1 0x May 2001 hy rk Order 1 e Order 2 Order 3 Order 4 Order5 Order 6 Order 7 o Order 8 Order 9 Order 10 e 24 20201 0 20 010202 O1 O10 1020102 21020501010 OOOO Qn Qn020 0 3rd or 7th Order Recommended 0 4 8 12 16 20 24 28 32 36 Frequency kHz Figure 45 88 2 kS s noise shaper curves _ Order 1 Order gt Order 3 _ Order 4 Order 5 Order 6 e Order 7 Order 8 Order 9 Order 10 40 d 44 dCS 974 User Manual dCS Ltd Noise Amplitude relative to No Shaping dB Noise Power dB rel no shaping 12 Actual Increased Noise Power top section Perceived F Weighted Noise Power bottom section Manual for Software Version 1 0x May 2001 96kS s Noise Shape Plot dCS 972 SW v1 54 3rd or 7th Order Recommended 12 16 20 24 28 32 36 40 Frequency kHz Figure 46 96 kS s noise shaper curves Weighted Noise Improvement vs Shaper Order dCS 972 SW v1 54 EK 96 kS s pies _ 44 1 kS s TS tran e a en Noise Shaper Order F
89. ll complete the name there deleting the right hand portion dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 If Store 4 has been named Demo the display will now look similar to this Emr tg Emr t a Emp t gt Dero lt EmrPt a Emr t a Emr t ar LIF 1 SE AE dE set St re Press the Enter button and a message window will appear in the display to confirm that the unit is storing the setup If you attempt to store a setup in a previously unused location without specifying a name a message window appears for two seconds stating First choose a name You can name your stored setups as anything you like provided the name is no longer than 15 characters If you have a fixed routine a few words may be enough to describe the setup If the unit is used for many different functions by several people we suggest using the following abbreviations to describe the setup Audio Input use AES1 AES2 RCA etc DA for Dual AES QA for Quad AES DSD for DSD SDIF DSDQ for DSD Quad Inout Rate use Au for Auto 44 for 44 1 kS s etc Sync source leave blank if synced to Audio Input or use AR for AES Reference MC for Multiple Channel Sync WC for Wordclock or Int for Internal Output Rate use 44 for 44 kS s or 2496 for 24 bits 96kS s or CD for 16 bits 44 1kS s Output Mode leave blank for Normal DA for Dua AES QA for Quad AES DSD2 for DSD SDIF 2 or DSD3 for DSD SDIFS dCS 974 User Manual Man
90. ll light The screen will then display the Status Screen for example Out 44 1 ks Input AESI Audio Input Modes Hormel W Length 244 bits Gain in P BEB H Shares Ott Bal L Bde HdE Connect a signal source to an appropriate input AES 1 2 3 or 4 SPDIF1 2 or 3 or SDIF 2 CH1 IN CH2 IN amp WCLK IN We recommend an AES3 source into the AES 1 input until you are comfortable with the unit The procedure below assumes you have connected your source to the AES 1 input dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Press the Recall button When the display changes to the Recall screen press the Recall button again The display will change to AES Auco No Fe AES AW FCDA 36 AES Augg d DA AUSLO H Fe WA Au CO HS Fe OS02 gt COHS Fe F LI J k L A E C D Select Store A the default setting with the rotary control and press the Enter button A message window will appear in the display to confirm that the unit is reading the setup Then when complete the message will go away the unit will lock and the Unlocked LED will go out The display then shows the status screen for the default setup as overleaf if you have a 96 kS s source connected to AES 1 otherwise the left hand number will adjust to what you have connected Irn D Oat 44 1 kos InFut AES Sync Audio Input OP Mode Hormal l HU Length 44 bits Gain H RHGb H Share OFF Bal L Bal L BB The co
91. nal can be generated from the signal but it can and this gives the lowest added noise power option It is noise shaping on its own but there are some circumstances where it needs help from additional dither e it can be added inside or outside an error shaping loop e it can be frequency shaped to match the ears response or not We can use techniques that Suppress error energy in the areas where the ear is sensitive and put it in areas where the ear is not sensitive Usually this shuffling around process costs us we remove a little from the sensitive areas and add back rather more in the less sensitive parts but that s life We still gain some improvements The table below gives the actual noise levels for 16 bit truncated signals with no dither various dither types noise shaping alone and noise shaping with dither 28 PDF Probability Distribution Function References to Rectangular Dither or Triangular Dither refer to the shape of the PDF of the dither dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 The O dB reference level is taken as the minimum noise we could possibly get away with the amount that simple 16 bit truncation 16 bit Q noise would give if it were well behaved which it is not Straight forward dither always adds noise it can only produce signals with a noise floor higher than Q noise on its own However the noise power added is a few dBs for simple types Noise shaping adds ra
92. nd of each bar are the Peak Hold indicators The indicator on the lower of the two bars shows that overloads full scale signals have occurred in the last monitoring period on that channel it says Over if you peer closely The decay of the overload is controlled by the Peak Hold function in the Leve Meters menu below Numerical metering to a resolution of 0 1dB can be set up instead for example for accurate alignment in comparisons See Meter Type below to do this the display will change to In KRIER Lut 44 1 k 5 s OO 2 OL 2 2 11 because the dCS 974 reduces the signal level by 0 01dB this can only occur if gain is applied or if the unit is in Format Conversion mode and the input signal goes to full scale dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Meter Type Bar or Numerical To change between Numerical or Bar level metering or to change the meter characteristics return to the Level Meters menu and press to display the options Fesk hold Eeter Tyre Bars Decay Time Select Decay and press Set to display the Decay time options Level Meters Instant These options give the following characteristics Normal the bar length decays away at 32 ms segment Faster the bar length decays away at 16 ms segment Fastest the bar length decays away at 11 ms segment Instant the bar length decays away completely in 32ms Select the required Decay lime and press Set Peak H
93. nformation ccecceceeceseeeeeeeeeeeees 123 contents of ebonx 110 CUS E 36 cursor direction cee eeeececeeeecececeeeeeececeeeeaees 60 Customise display does not work 122 Manual for Software Version 1 0x May 2001 customising the deplay 50 D BIREN 3 De Emphasis menu 50 default setup Joadmg 10 demultiplexing EN 23 digital data formats ccccceeceeeeeeeeeeeeeees 70 digital interface specifications 00000000 86 Digital Silence menu 50 display backlight remains on 56 57 Display Customise men 50 display is unreadable ccccceeceeeeeeeees 121 Display men 40 60 display shows strange characters 121 Display backlight timeout eee 60 Display bngohtness 60 display changing sannonnnnnnnnnnnnnnnnnnnnnnnnnnnne 50 Display contrast 60 display CGC E 68 DNET apearen Rais 85 104 105 108 dither generators cccecceeeeceeeeseeeeaeeeeaeeees 85 Dither iNdiCator cccccecceseeceeeeeeeeeeseeeeseees 69 Dither Menu ccccseeceseeceeeecseeseeseseueesaues 47 dither spectra ec cececeeceeeeeeeeeeeeeees 95 107 dither histogram cccecceecceeeeeeeeeeeeaeeeaees 85 dither NOISE DOower 85 dither PDF wiscecsunusseicdcauntntataesdvat hes niuia 94 104 Dither recommended l an nennennennennennennnnnnnne 19 dither weighted noise D ower 85 dither when is it neecdecd eee 108 downsampling
94. nit re locks Proceed to Step 3 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Step 3 Setting a Conversion If you need bit for bit operation in a different output format proceed to the Format Conversion section If you want to change the sample rate or the word length or process the data in some other way proceed to the Sample Rate Conversion section Format Conversion TOP LEVEL Pure Format Conversion Default Default DSD SDIF 3 Figure 3 Pure Format Conversion Press the lt button scroll down to Format Conversion press the button and press the Set button This sets Pure Format Conversion to On and disables the Sample Rate Conversion menu If the Fs In not Fs Out information box appears on the display press the Set button to make the Output Sample Rate match the Input Sample Rate Scroll down the Format Conversion menu to Output Mode and press the gt button The cursor should be beside Normal Choose one of the settings from the following list scroll to it and press Set e Normal The Inout amp Output Sample Rate must not be higher than 96kKS s Bit for bit data will be available on all of the AES SPDIF or SDIF 2 outputs e Dual AES The Input amp Output Sample Rate must be 88 2 96 176 4 or 192kS s Dual AES bit for bit data will be available on the AES 1 AES 2 output pair and the AES 3 AES 4 output pair Do not use the other outputs e Qua
95. ns USING ccccceeeeeeeeee eee 61 mMenu CS xk ora eh eects a a acne 35 MENU NAVIGATING ceccseceseeeeeeeseeene esse eeees 36 NN IER USING EE Els message handling A 70 MOOG EE 38 39 MOOG EE 38 41 Monophonic output cc cceeec cece eeeeeeeeeees 121 multi channel operation 29 30 31 32 multi channel SynC nnnannannnnannannnnnnnnnn 42 81 multi channel sync multiple rates 83 multi channel DGSDtoDb 42 multi channel master ccececeeeeeeeeeeeeees 81 multi channel synchronisation 0 66 multiple sample rate output eee 32 N navigating the menu 36 NO OULDUL SIQM Al EE 120 NOISE ON OULDUTS EE 120 noise performance DCH 15 noise performance GACI 72 noise shaper curves 0 1n 100 101 102 noise shaper weighted noise improvement 102 Kielen Le BE 84 Noise Shaping mdcator 69 Noise Shaping menu 47 noise Shaping epechra 107 noise shaping NOISE DOWer ee 105 Noise Shaping recommended 19 Normal output Mode ees 45 O one channel only has signal 0nn0nn0nnaann 121 operating Conditions cece cece cece eee eeeeeeees 92 Operation buttons ccc ceecceeeeeeeeeeeeeeeees 68 aide 114 options changing WE 114 output bandwidth is IOW cceecceeeeeeee es 121 Output Mode menu 45 output Mode DD 45 output mode DSD Quad anes 45 output mode Dual AE 45 output mode Quad AE 45 output mode Setting
96. nverted Phase Right inverted Both inverted l On ff O De emphasis 50 15 us add or remove De emphasis CCITT J17 Emphasis 50 15 us Emphasis CCITT J17 De Pre emphasis Input Sync Source Output Mode Word Length Noise Shaping Dither CRC Errors Left E CRC Errors Right Parity Errors Left Parity Errors Right Invalid Errors Left Invalid Errors Right Display Customise Error Monitor Hold Unhold Reset All Errors Off Sine Square Test Generator Amplitude Generator Frequency Brightness Contrast Cursor Up Down 1 mins 3 mins Backlight off after mins Display Self Test Info ormal Bit Activity D Faster None Monitor Sua Fastest 320 ms Instant 640 ms 960 ms Level Meters Peak Hold 1280 ms 1600 ms Bar Infinite Table 1 Menu Tree dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Navigating through the Menu what the On Screen symbols mean Once the unit has powered up and the Status screen is displayed you can start navigating through the menu This section explains how the keys operate and what the various on screen indications mean To start pressing either the lt or button brings up the top level of the Menu ate Lonversion part Convers ion Error Monitor Test Into i Bit Activity Monitor Level Meters sp lau The symbol is the cursor and an indication that there are sub menus available below this
97. nverted input signal will now be available at all of the outputs Connect the output of your choice to the input of a 44 1 kS s recorder DAC or other equipment you wish to drive It will now lock to the dCS 974 Note that all the outputs are active when the dCS 974 is locked They may all be connected to external equipment simultaneously if required Similarly all of the inputs may be connected as the active one will be selected by the Audio Input Select menu Now you will need to familiarise yourself with how the control software and menu system work Read the short section on Navigating through the Menu what the On Screen symbols mean page 36 so you know how the buttons and cursor work You may also find it convenient to refer to the Quick Start Guide while you are getting to know the unit dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Installing the Unit in a Rack The unit is supplied with 19 rack mount ears fitted If it is to be installed in a 19 rack the ears supplied may be used to locate it in the rack but IMPORTANT The ears should not be used as the only mechanical support The unit should rest on a Shelf or be supported in some other way The ears will just locate it in the rack and stop it sliding forwards If the unit is not to be rack mounted the ears may be removed dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Manual part no DOC 1241121A1 Page 11
98. o enter first the Sample Rate Conversion menu then the Audio Input Select menu Use the rotary control to scroll down the list until the cursor is beside DSD Quad Press the Set button to select it There will be a noticeable delay while the DSD code loads then the screen will change back to the Sample Rate Conversion menu Proceed to Step 2 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Step 2 Setting the Sync Source Switch on the source equipment If appropriate load a disk tape and set the machine in PLAY mode to ensure it is generating a digital audio data stream The dCS 974 will be set to sync to the selected Audio Input and the Input Sample Rate will be Auto detected The unit should lock and the Unlocked indicator should turn off If you do not want to use an external reference clock proceed to Step 3 TOP LEVEL Sample Rate Conversion Default Lab Ref 10MHz Figure 2 Sync Source Selection If a stable clock source is available you can reduce jitter in your system by syncing to it Choose one of the following two sections Syncing to an External Wordclock If you want to synchronise your system to Wordclock from a Master Clock such as the dCS 992 or other stable source do the following set the Master Clock sample rate to match the source probably 44 1 or 48kS s Connect either a Wordclock or AES EBU output from the Master Clock to the clock input on the
99. old Select Peak Hold and press Set to display the Peak Hold options Level Meters eak hold Reser The unit notes the highest signal peak on each channel and turns on the appropriate meter segment on each bar The Peak Hold segment remains for the set time and is then replaced by the next signal peak The menu options function as follows dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 None Disables the Peak Hold feature 320ms thru 1600ms Sets the Peak Hold time Infinite Sets an infinite Peak Hold time Reset Resets the Peak Hold segments to the current peak Select the required option and press Set Infinite allows the highest peaks in a track or long passage to be displayed you might want this to do a manual maximise Select Infinite and press Set At the start of the track select Reset and press Set Press Status to display the meter At the end of the track the highest peaks will be displayed Select Reset again and press Set to clear the peak readings Using the dCS 974 to monitor a track If you just want to use the dCS 974 as a level monitoring device you can control the bandwidth you monitor by setting the output data rate 44 1kS s will give approximately 20kHz bandwidth whereas 96kS s will give approximately 40 kHz bandwidth The meters can be used to monitor DSD by setting a DSD to PCM conversion and using the appropriate output data rate Watch Out for this One
100. on twice to enter first the Sample Rate Conversion menu then the Audio Input Select menu Use the rotary control to scroll down the list until the cursor is beside PCM SDIF 2 Press the Set button to select it The screen will change back to the Sample Rate Conversion menu Proceed to Step 2 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Connecting to a Dual AES Source Check that your source equipment is capable of Dual AES operation Connect the AES 1 or AES A output on your source equipment to the AES 1 input on the dCS 974 rear panel and the AES 2 or AES B output to the AES 2 input using two XLR cables Ensure the cables are not swapped Press the button twice to enter first the Sample Rate Conversion menu then the Audio Input Select menu Use the rotary control to scroll down the list until the cursor is beside Dual AES Press the Set button to select it The screen will change back to the Sample Rate Conversion menu Proceed to Step 2 Connecting to a Quad AES source Check that your source equipment is capable of Quad AES operation Connect the AES 1 output on your source equipment to the AES 1 input on the dCS 974 rear panel the AES 2 output to the AES 2 input the AES 3 output to the AES 3 input and the AES 4 output to the AES 4 input using four XLR cables Ensure the cables are connected in the correct order Press the button twice to enter first the Sample Rate Conversion menu then the
101. onnect a source of CD material to the RCA input on the dCS 974 Enter the Sample Rate Conversion settings below Connect Dual AES data from both AES 1 and AES 2 outputs to a DAC of your choice lf your DAC is a dCS Elgar dCS Delius or dCS 954 you can set the Output Sample Rate to 192kS s instead Sample Rate Conversion settings Sample Rate Conversion On Audio Input Select Sync Source Inout Sample Rate Output Sample Rate Output Mode Filter Output Wordlength Noise Shaping Dither Detect Silence AES Message Edit SPDIF Message Edit SPDIF 1 Audio Input Auto 44 1 kS s 96 kS s Dual AES Filter 2 24 Off Off Off Professional On Non Audio Off Mode Stereophonic Professional On Non Audio Off Copy Permit On Format 2 Ch Gen Format dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 General Sample Rate Conversion and Distribution From ANY format AES SPDIF Toslink SDIF 2 at ANY sample rate 11 025k 12k 16k 22 05k 24k 32k 44 1k 48k 88 2k or 96kS s or Dual AES at 88 2k 96k 176 4k or 192kS s or Quad AES at 176 4 or 192kS s or DSD SDIF 2 DSD SDIF 3 or DSD Quad A ge our ORO O Ac i DSD SDIF MAINS FUSE 2AT ON OFF e 4 CG Ce To ALL formats AES SPDIF Toslink amp SDIF 2 at ANY sample rate 11 025k 12k 16k 22 05k 24k 32k 44 1k 48k 88 2k or 96kS s Dual AES at 88 2k 96k 176 4k or 192kS s Quad AES at 176 4 or 192kS s
102. ould be allowed to accommodate cable connectors The rotary control knob protrudes 22mm from the front panel note iii The high quality case is necessarily heavy Operating Conditions consideration should be paid to appropriate support shelving when installing the units in a rack The case of the dCS 974 has no ventilation slots or fan cooling to give It dissipates relatively low power so that usually allowing natural convection provides enough cooling Do not install the unit near heat sources such as radiators air ducts or direct strong sunlight Ambient should not exceed 50 C should not fall below 0 C and should be non condensing If in doubt the easy quiet operation does not need to be installed in a machine room internal temperature stability improved electrical safety long term reliability no regular maintenance or cleaning requirements test is the dCS 974 is happy to work anywhere a human is dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Manual part no DOC1241121A1 Page 93 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual dCS Ltd Manual for Software Version 1 0x May 2001 dCS 974 PERFORMANCE CURVES 0 5 0 4 0 3 0 2 Fraction of Time Dither Occupies Bin 0 1 0 0 The graphs on the following pages show key performances of t
103. page 99 The transient responses of the filters in the 96 kS s 44 1 kS s conversion are shown below fe stopped 1 2 00 Vedi pos 2 000 10 00 1 Ms de m 2 00 Vedi UE 2 00 V O0Iy ms 2 00 Wediv 650 00 us 150 00 us 250 00 us 479 EP 100 usdi repetitive Trigger Made current minimum mas imum average Edge Yavg inot found O o0000 Y 0 00000 O 0g0000 W d1 150 0 mY Figure 19 Transient Performance of 44 1 kS s Filter Options Use of higher sample rates gives much tighter transient response with much less energy smeared into the pre and post ringing The transient responses of the 96 kS s output filters are shown below 14 Filters always have some ripple For zero ripple filters this is in the udB to pdB region For conversions where the lowest rate used is 16 kS s 22 05 kS s or 24 kS s some conversions cut off at 33 of the lowest sample rate dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Zoo running 1 2 00 Vedi pos 1 000 Y 10 00 1 Ms de m 2 00 Ydi mz 2 00 V edi ms 2 00 W div ma 2 00 Wi div 550 00 us 50 00 us 450 00 us AYQ 100 us div repetitive Trigger Mode current minimum mas imum average Edge Vavg LC inot found O 00000 Y O 00000 W O 00000 Y d 150 0 mY Figure 20 Transient Performance of 96 kS s Filter Options Spurs Sample rate conversion is a linear process so spurs are not caused by mechanisms that produce harmonic
104. ppy discs the remote software is supplied on Then run the remote programme with whatever units you want connected The software will scan the RS 232 chain for units this takes a while to see what is connected It then reports back and for each there is an info button This gives you the option of installing new software in that unit The display software comes in an EPROM which has to be manually installed The top cover has to be removed the old EPROM on the front panel board removed from its socket 1 4 of the way from the right hand edge looking at the unit from the rear and the new one installed Make sure it is installed the right way round IMPORTANT Disconnect from the mains before removing any covers or changing the fuse dCS 974 User Manual dCs Ltd Warranty Initial Warranty Extended Warranty Warranty Exclusions Obtaining Service Manual for Software Version 1 0x May 2001 dCS Ltd warrant this product against defects in materials and workmanship for a period of 90 days from receipt by the end user Warranty repairs must only be carried out by dCS or an authorised dCS Distributor The period of the Warranty cover may be extended to 1 year from receipt by the end user at no extra cost by registering your purchase with dCS Your reseller should have arranged this on your behalf by filling in an Owner Registration form at the time of sale and returning it to dCS If you do not receive an Extended Warranty Certi
105. r Co OR 16 bit 44 1kS s digital audio 44 1kS s Wordclock dCS 992 Master Clock AES 1 AES 2 AES 3 AES 4 Q p 2 SS AES EBU Output EE A SN BU REFERENCE LOOP es e SW cor SPDIF N ouN D O Ge TOS TEE AES EBU OUTPUTS Dual AES up to 24 bit 192kS s itivi eferen e In eference Ou FE AE Se SRJ es Wiel We Balanced Unbalanced Analogue Analogue Outputs Outputs Figure 11 Using a Master Clock If a Master Clock such as a dCS 992 is available and the driving source is locked to it the dCS 974 may be locked to it Either connect the Master Clock to the AES Ref Loop In and select AES Loop Term as the Sync Source or connect the Master Clock to the SDIF 2 WCLK IN and select Wordclock as the Sync Source IMPORTANT Since the Output Sample Rate of the dCS 974 is different to the Master Clock rate the DAC would be unable to lock to the data from the dCS 974 if it were sync ed to the Master Clock So slave the DAC to the dCS 974 NOT to the Master Clock dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Converting Quad AES to CD Format 24 bit 176 4kS s Quad AES Optional 44 1kS s Wordclock from 8 track recorder to 8 track recorder U REFERENCE LOOP x AES EBU OUTPUTS 16 bit 44 1kS s CD format Figure 12 Converting Quad AES to CD format You can archive in
106. r is best for all applications The menu is dynamic that is it updates to show valid selections For example Fs In 96kHz Fs Out 44 1kHz has 4 options and shows ONES 1 Or cut i cut cut A cut 4 While Fs In 96kHz Fs Out 88 2kHz has only one option and shows ample Fa OnVvers lor Filter BFilter cut 1 The dCS 974 remembers the last filter selection for every conversion so if you choose Filter 4 for 9644 1 and Filter 2 for 9648 these separate settings will be stored and loaded when you switch between them Select the required Word Length from the list and press Set The dCS 974 generates long word length 24 bit data and truncating this adds extra noise It can also add highly undesirable behaviour at low signal levels We recommend that you use a high order noise shaping function but see the section Word Length Reduction page 104 and try for yourself This is a seriously major topic and you should experiment The reports we receive from users suggest that for PCM work Filter 2 is well suited to some classical music and that Filters 3 and sometimes 4 suit rock However views vary quite a lot dCS 974 User Manual dCs Ltd Noise Shaping Dither 8 Manual for Software Version 1 0x May 2001 Noise Shaping is a technique in which the noise energy added by truncating a longer word is pushed into the less audible parts of the spectrum giving a useful improvement in perceived noise level The
107. rature Stability 15 ppm over operating temperature range Synchronising to source Pull in range 300 ppm about nominal frequency Lock in time lt 2 seconds for most combinations The PLL is very robust and will lock to very poor signals if necessary Data is decoded using a much wider band faster PLL so AES3 type low frequency jitter on the input clock can be handled and will be cleaned If you need to synchronise several items of digital equipment we recommend using a dCS 992 Master Clock dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Sample Alignment The dCS 974 aligns samples such that SDIF WCLK OUT aligns with AES3 samples out the rising edge of wordclock aligning with the start of the first illegal code in the X Z subframe preamble and the falling edge aligning with the start of the Y subframe preamble Se running 1 2 00 Wediv DN lim 2 500 1 000 1 308 de 2 2 00 VWrdiv DN lim 4 000 10 00 1 1M de 1 0000 us O 000 s 1 0000 us 200 ns div repetitive Trigger Mode Edge 1 2 250 Figure 21 Wordclock and AES3 outputs 96 kS s fe running 1 2 90 div BA lim 2 500 VM 1 000 1 30s de 2 2 00 Vrdiv DN lim 4 000 10 00 1 Ms de 2 5000 us O 000 zs 2 2000 US 3090 ns div repetitive Trigger Mode Edge 1 2 250 Figure 22 Wordclock and AES3 outputs 44 1 kS s dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 When SDIF WCLK
108. re is a trade off between noise floor improvements in the mid band where the ear is most sensitive and increased noise at the top of the audio band which the ear does not hear but your system might Noise Shaping is achieved by processing the truncated bits so it is not available if the output word length is the same as the input word length Dither is different and additional to Noise Shaping and is necessary under some circumstances dCS consider Dither to be unnecessary in many situations Noise Shaping alone is sufficient and lower noise See the section Word Length Reduction page 104 for more information Entering the menu shows 2 Rate Conversion Hoise Sharing BUFF Let Order ZP Order Order Order Order Select the required Noise Shaping characteristic from the list and press Set The options are up to 10 order for sample rates up to 96kKS s Noise Shaping is not applicable to DSD For 32 kS s 44 1 kS s 48 kS s 88 2 kS s and 96 kS s the curves are individually optimised Entering the Dither submenu shows ONES LOP Triangular Tor Hat H Shared Triangular Select the required Dither characteristic from the list and press Set N Shaped Triangular means Noise Shaped Triangular For more information on dither and different dither types see the section Dither on page 85 and Figure 31 to Figure 34 If you need curves optimised at other sample rates contact us dCS 974 User Manual dCs Ltd AES Mes
109. reat Chesterford Court Great Chesterford Saffron Walden CB10 1PF U K Serial No 974 located on the underside of the unit Name of new owner Date purchased Website Name of registered owner Signed x
110. rlds the high noise floor in the 0 6kHz area of straight dither and the high total noise of noise shaping However some people use it What does it look like Figure 48 gives the spectra of 16 bit truncated 44 1 kS s signals with a 90dBO sine present for two dither only signals Top Hat Noise Shaped Triangular a 10 order noise shaped Signal and a 10 order noise shaped signal with added Noise Shaped Triangular dither The equivalent simply truncated spectrum is shown in Figure 49 separately because it is so revolting In it we can see that at the signal level shown 90dBO error power from the quantising truncation is beginning to pile into the fundamental which is showing an amplitude error of 1 3dB This would show up on a conventional linearity plot although the sign of the error could be either way for example from synthesisers 32 for comparison with the table 10 and 9 order noise shaping are very similar dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Noise Shaper Noise Shaper with Dither and Dither Only Comparison dCS 972 SW v1 54 60 16 bit truncation Noise Shaped Triangular dither 16 bit truncation Top Hat dither 80 16 bit truncation 10th order noise shaping Noise Shaped Triangular dither a mt 16 bit truncation 10th order noise shaping no dither DEET DW ee a Oe vw e 100 vd S Da m Ze Pa E ad Bi D ge 3 ae FY a mt AE
111. s Single complex zero 37 10 Single complex zero Real zeros 2 0 10 Real zeros only Table 4 DSD Filter Summary Signal to Q Noise and SACD Specs Although 120dB SNR over the 0 20 kHz band is a good target it does not match the ears response that well The F weighted curve is currently accepted as a good model for the ear and we can use this to weight the noise produced by the various filter choices Such a weighting is shown in Figure 38 on page 98 and DSD gives very good performance using such a weighting better than 23 bit pcm The figure shows that Filter 6 and 7 give more F weighted Q noise suppression in the audio band than Filters to 5 Filter 6 gives around 20 dB more suppression than Filters to 5 under all circumstances and Filter 7 gives 20dB more suppression below 10 kHz dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 SACD specifies ultrasonic noise in two bands These are specs informative specs E2 and E3 and filter performance for a number of specs including these are given below The measurements given have been made using a Fourier Transform based method Filter Comments SQNR SQNR E2 spec E3 spec 20 kHz F weighted dB dB dB dB 1 High SQNR 126 14 136 56 25 98 28 96 high stability 2 High SQNR 127 23 138 76 25 85 28 95 3 High SQNR 124 66 134 38 27 32 30 49 very high stability 4 Extremely high 122 07 129 91 25 54 29 53 stability 5 Reduced 100k 12
112. s then the Output Sample Rate menu would look like this dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 OUTPUT SAMPLE RATE kS s 11 025 12 16 22 05 24 32 44 1 48 88 2 96 176 4 192 DSD 11 025 1 pass 1 pass 2 pass 1 pass 1 pass 2 pass 1 pass 2 pass 1 pass 2 pass 2 pass 2 pass 2 pass nD 12 1 pass 1 pass 2 pass 1 pass 1 pass 2 pass 2 pass 1 pass 2 pass 1 pass 2 pass 2 pass 2 pass y 16 2 pass 2 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 2 pass 1 pass 2 pass 2 pass 2 pass et 22 05 1 pass 1 pass 1 pass 1 pass 1 pass 2 pass 1 pass 1 pass 1 pass 2 pass 2 pass 2 pass 2 pass E 24 1 pass 1 pass 1 pass 1 pass 1 pass 2 pass 1 pass 1 pass 2 pass 1 pass 2 pass 2 pass 2 pass D 32 2 pass 2 pass 1 pass 2 pass 2 pass 1 pass 1 pass 1 pass 1 pass 1 pass 2 pass 2 pass 2 pass Si 44 1 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 48 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass r 50 2 pass 2 pass 2 pass 2 pass 2 pass 2 pass 1 pass 1 pass 2 pass 2 pass 2 pass 2 pass 1 pass 88 2 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 2 96 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 1 pass 2 pass 1 pass 1 pass Z 176 4 2 pass 2 pass 2 pass 2 pass 2 pass 2 pass 1 pass 2 pass 1 pass 2 pass 1 pass 2 pass 1 pass 192 2 pass 2 pass 2 pass 2 pass 2 pass 2 pass 1 pass 1 pass 1 pass 1 pass 2 pass 1 pass
113. s 124 software updating s nannennennnnnnennnnnnennn 117 SPDIF electrical interface cceeeeeees 86 SPDIF input selecting eee ceeeeeeeeeee ees 11 SPDIF EENEG 66 SPDIF Message Edit menu 48 SPDIF message bandlmg 88 89 SPDIF optical interface cccceccceeee scenes 87 SPDIF output Conpechng neers 18 SPDIF OUIDUIS ee ee 67 specifications digital mtertace 86 SpuriouUS FESPONSES c cece cece eeceeeeeeeeeeeeeees ZA SEET ee 14 BIN ese aie eee eae ee eee eae 71 Status DUON BEEN 68 step by step Ooude 10 stereo image is out of Dosmton 121 stereo image IS poor 121 Store DUON WEE 61 68 store SEET 64 teller 61 SUDDIY VOIlAGQC EE 114 supply voltage Setting ccccecceeceeeeeeeees 67 Swap Channels menu 49 SVC ul E E 66 SVG IAK srera a a 42 81 SYNC link USING ccceceeeee scene 29 30 31 42 Manual for Software Version 1 0x May 2001 SYNC Source men 41 sync source setting ccccecceeeeeeeeseeeseeeees 13 sync to AES EEEE 14 41 sync to Audio lnput scene eeees 41 sync to Internal clock aannnnnnnnnnnnnnnnnennennannna 41 sync to video sample rates 0 n0nn0nnannan 114 SYNC to Wordclock 13 41 T IES MENU EEN 39 53 tone ON OUTPUTS ccccecseeseeeseeeseeeeeeeees 121 TOD e LEE 38 troubleshooting NN 120 truncating the wordlengt 19 Pancal OM irctes ainsi ee 104 truncation spectra ee 96 106 107 typic
114. sage Edit Manual for Software Version 1 0x May 2001 This menu sets the message bits on the AES outputs Professional On Off Non Audio On Off Mode Source Destination SPDIF Message Edit Select then press Set to toggle between On and Off Select then press Set to toggle between On and Off Select the audio data format then press Set Options are Not indicated Two channel Primary Secondary Stereophonic Select each of the four bytes in turn press Set turn the rotary control to change the character as necessary and press Set again to accept Press lt to return to the previous menu and the four characters will be displayed beside Source Set up similarly to Source This menu sets the message bits on the SPDIF outputs Professional On Off Non Audio On Off Copy Permit On Off Format Gain Balance and Maximise Select then press Set to toggle between On and Off Select then press Set to toggle between On and Off Select then press Set to toggle between On and Off Select the audio data format then press Set Options are 2 Channel General Format Compact Disk 2 Channel Encode Decode DAT This menu allows gain output level and balance to be set or an automatic gain setting to get the highest possible level without overload for CD preparation for example The balance control works in a different way to conventional analogue balance controls and although is easy to operate you shou
115. sages Cyclic Redundancy Counts CRC s are generated from the Channel Status message The Dual AES interface allows an 88 2 or 96kS s 24 bit signal to be coded as two standard 44 1 or 48kS s 24 bit AES data streams recorded as four tracks on a recorder with standard capacity replayed and decoded back into a single data stream Operation of the Dual AES interface at double speed allows the unit to input or output 2 wire 176 4 or 192 kS s 24 bit data and convert to and from this The Quad AES interface allows an 176 4 or 192kS s 24 bit Dual AES data stream to be coded as four standard 44 1 or 48kS s 24 bit AES data streams recorded as eight tracks on a recorder with standard capacity It may be replayed and converted into a Dual AES stream a single wire format or DSD SDIF 2 PCM message bits are internally set to zero with the exception of the block code which is implemented The SPDIF interface has no CRC s as per definition Data formats for both SPDIF electrical and SPDIF optical are identical DSD has at the time of writing no messaging structure Contact dCS for more details Data formats use either the SDIF 2 system two data channels and third clock channel the SDIF 3 format two data channels with embedded clock or the DSD Quad format four AES3 style data streams 12 At present we do this because there is no standard on what to do with the excess or shortage of bits that is created by a sample rate change If this cau
116. ses you a problem call us we can probably do something else if we are clear what that ought to be dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 DSD Filter Options DSD is a single bit very high sample rate 2 822 MS s format where the single bit words are heavily noise shaped to push noise energy above the audio band The frequency response is very high well above 100 kHz although at these high frequencies noise is also present For SACD purposes 0 dBOpsp is set at 6 dB below the peak to peak level one might expect a full scale sinewave to occupy this ensures that artefacts that begin to occur at the limits of the DSD amplitude range do not move down into the audio band The 0 dBOpsp level is shown graphically in Figure 39 page 98 The dCS 974 offers a number of different DSD modulators as Filter options All the modulators have the same signal frequency response They differ in the way they shape the out of band Q noise and in how far they suppress the in band Q noise Filters to 5 suppress Q noise at least 120 dB below the nominal OdB DSD signal which is one of the marketing specs for SACD Filter Comments SQNR Stability Description 20 kHz dB High SQNR high stability 1 7710 Two complex zeros High SQNR 8 2 10 Two complex Zeros High SQNR very high del Two complex stability zeros Extremely high stability 3 0 10 Two complex Zeros Reduced 100k noise 7 1 10 Two complex Zero
117. splays a Status screen similar to this Ost 44 1 KG Input AESI Audio Input Mode Hormal LU Length 24 bits Gain 8 46 H Share OFF Bal L AdB FE Ade The Power and Unlocked indicators should be lit the other indicators should be off dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Step 1 Selecting an Input TOP LEVEL Sample Rate Conversion Default Multi Channel Sync Figure 1 Audio Input Selection Choose one of the following five sections Connecting to a Single AES or SPDIF source Connect your source equipment to the matching input on the dCS 974 rear panel using suitable cables An AES3 source XLR connector may be connected to any of the four AES EBU inputs Press the button twice to enter first the Sample Rate Conversion menu then the Audio Input Select menu Use the rotary control to scroll down the list until the cursor is beside your chosen input either AES 1 AES 2 AES 3 AES 4 SPDIF 1 RCA SPDIF2 BNC or SPDIF3 Toslink Press the Set button The screen will change back to the Sample Rate Conversion menu Proceed to Step 2 Connecting to a PCM SDIF 2 source Connect the SDIF 2 output on your source equipment to the upper block of DSD SDIF connectors on the dCS 974 rear panel using 3 coax cables Connect CH1 out to CH1 IN CH2 out to CH2 IN CLK out to WCLK IN Fit a 75Q terminating plug to the nearby LOOP OUT connector Press the butt
118. stereo output signal is expected but one channel of the input appears on both channels of the output e Check that the receiving unit expects two wire AES or SPDIF mode rather than double speed single wire Tone appears on the outputs e Press the Status button and check that the MEME label is NOT visible If itis select Test Mode and set the Test Generator to Off e Low level idle tones sometimes appear on the outputs if the signal on the input drops to a level below the output word length and Noise Shaping is on with no Dither This may arise during editing sessions for example where digital silence is coming in to the unit but the Detect Silence function is off This situation will usually not arise if an unedited input from an ADC is being used although even in these circumstances enough noise shaping must be used Consider using either Dither or Detect Silence or both The LCD display is unreadable but the Power LED and possibly some other LEDs are lit e Display Contrast may have been set to minimum Switch off the unit wait 10 seconds hold down the Status button and switch on The unit will power up using default settings including high contrast Alternatively Store A is pre loaded with default settings Press Recall slowly twice then press Enter to recall from it Strange characters appear on the LCD display e This can be caused by power line drop outs or switching the unit off and on rapidly Switch off wait
119. t and the AES 2 output to the AES 2 or AES B input using two XLR cables Ensure the cables are not swapped An identical Dual AES pair is available from the AES 3 and AES 4 outputs Connecting the Quad AES or DSD Quad Outputs Check that your destination equipment is capable of Quad AES or DSD Quad operation If you have set Output Mode to Quad AES or DSD Quad connect the AES 1 output on the dCS 974 rear panel to the AES 1 input on the destination equipment the AES 2 output to the AES 2 input the AES 3 output to the AES 3 input and the AES 4 output to the AES 4 input using four XLR cables Ensure the cables are not swapped Connecting the DSD SDIF 2 or DSD SDIF 3 Output Check that your destination equipment is capable of DSD operation If you have set Output Mode to DSD SDIF 2 or DSD SDIF 3 connect the lower block of DSD SDIF connectors on the dCS 974 rear panel to the destination equipment using three coax cables Connect CH1 OUT to CH1 in CH2 OUT to CH2 in and WCLK OUT to CLK in Note that the default setting for the DSD output clock is 44 1kS s Wordclock rather than Bit clock at 2 82MS s Proceed to Step 5 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Step 5 Reducing the Output Wordlength If you are using Pure Format Conversion or DSD output modes the Output Wordlength cannot be changed Proceed to Other Settings If you are performing a sample rate conversion with PCM outputs the destina
120. t attempt the changes yourself The unit s performance or reliability may be impaired and the warranty will be invalidated dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Manual part no DOC 1241121A1 Page 115 Document No OS MA A0124 112 1A1 Contact dcs on 44 1799 531 999 email to more dcslitd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 MAINTENANCE AND SUPPORT Hardware Service amp Maintenance dCS audio products are designed not to need regular maintenance and contain no user serviceable parts e there are no moving parts e there are no short life or wear out parts used e the units have no holes through which liquids or contamination can normally enter e no dust deposits build up to degrade performance All parts are replaceable or upgradeable by dCsS for a period of at least five years from the original purchase date If your unit is damaged in some way please contact your Distributor or dCs User Changeable Parts There are no user serviceable parts inside the case Routine maintenance is not necessary and repairs are generally carried out by dCS since this allows us to thoroughly verify the results before shipment There is a mains fuse in the mains socket accessible from the outside of the unit This may be changed by the user The current consumption of the unit is very low 190 mA at
121. t different sample rates and be the master DVD production may require different sample rates for different channels this set up will give real time 48 kS s rear channels and 96 kS s front channels from a multi channel 44 1kS s source See Figure 16 overleaf For all dCS 974 units set the Multiple Channel Sync option to On They will all set up as slaves Make sure that all the other settings are the same on each unit in a group version 2 0 or higher software dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 48kS s Ch19 amp 20 48kS s Chi7 amp 18 FROM SOURCE 48kS s Ch15 amp 16 NCE LOOP Boao AES CLK OUT rs SYNC INPUTs GJR 48kS s Ch13 amp 14 TO RECORDER 44 1kS s WORDCLOCk 96kS s Chi amp 2 FROM SOURCE 96kS s Ch3 amp 4 96kS s Ch5 amp 6 96kS s Chi amp 8 Figure 16 Multi channel Sample Rate Conversion with multiple sample rates out dCS 974 User Manual dCS Ltd Manual for Software Version 1 0x May 2001 THE SOFTWARE MENU AND SETUPS Sample Rate Audio Input Select TOP LEVEL Greyed out menu entries Conversion SRC Format Conversion FC menu Sync Source Multiple Channel Sync Input Sample Rate Output Sample Rate Audio Input AES Loop AES Loop Terminated Wordclock Internal Lab Ref 1OMHz On 192 kS s 176 4 kS s 96 kS s 58 2 kS s 48 kS s 44 1 kS s 32 kS s 24 kS s 22 05 kS s
122. tea una ieusacein Gadd ou unset wbaduea cnet 73 TUES EEN 73 filter passband ripple cecceeeeeeeeeeeeeees 73 filter phase response 73 filter transient response o nonnnnnnananna 45 73 ters LD EE 45 First choose a name eee ee eens eee 62 first time user 110 fixed Re 63 flickering level meter 59 format conversion c cececeeceseeceseeeeeeeeeeeens 15 Format Conversion mode 38 39 format converting tO am 25 formats digital data 70 leie del EE 68 fuse Mals erada a T 116 G Gain JEE dees tee ee eech 69 Gaim MENU ose stews Eeer eer 48 Gal USING EE 48 SE ii MAD NEEN 55 Generator Amplitude adjustment 54 Generator Frequency adusiment 54 Generator menu 53 Generator DSD EEN 53 Generator frequency resolution 0 54 Generator initial settingS 0068 54 55 generator SYNCING ccceccceeeceeeeeeeeeeeeaeeeees 53 Generator usimg 53 Getting Started cece ceeeseeeeeeeeeeeeeeees 110 GPS SYNCING lOr 41 66 GlOUD Re TE 15 guide to basic Setup 10 H hardware updates 119 Manual for Software Version 1 0x May 2001 I in out combinations 2 cece eee eeeecececeeeeeeeeees 43 natator BAlaNnCe ME 69 macar DUNG EE 69 MACAO Galie 69 INGICATOL OR FMD EE 69 indicator Noise Shaping cccceeeeeeees 69 INGICALOL Gun LE 69 indicator POWER Sich icteric biaieiati eases 68 Indicator Unlocked 0 cece
123. ther more noise but it can be made to add it in parts of the spectrum that the ear is less sensitive to so the perceived noise F weighted noise is lower up to three bits lower It results in a signal that the ear hears as having a far lower noise floor than a 16 bit truncated signal rather than the not much worse of dither alone even though there is really more noise present Truncation Type with Noise Noise Comments 44 1 kS s data rate unweighted F weighted rel 16 bit Q rel 16 bit Q noise noise Unpleasant low level effects Okay can show noise modulation at low signal levels All noise modulation and unpleasant effects removed but noise floor is high 16 bit truncation 16 bit truncation with Top Hat dither 16 bit truncation with Triangular dither 16 bit truncation with Noise Shaped Triangular dither 16 bit truncation with 2 order noise shaping and no dither 16 bit truncation with 2 order noise shaping and Noise Shaped Triangular dither 16 bit truncation with 9 order noise shaping and no dither 16 bit truncation with 9 order noise shaping and Noise Shaped Triangular dither Table 16 Dither and Noise Shaping Noise Powers All noise modulation and unpleasant effects removed Not much perceived noise penalty Okay with input noise floors down to 102dBO Unconditionally free from truncation effects with all inputs Okay with input noise floors down to
124. tion equipment can handle 24 bit data and you do not want to reduce the wordlength then leave the Output Wordlengin set to the default of 24 bits and set Dither to Off Proceed to Other Settings The dCS 974 generates 24 bit data regardless of the input word length If the destination equipment cannot handle 24 bit data the Output Wordlength MUST be set to match Noise Shaping and or Dither MUST be applied to smooth the transitions If the extra bits are just ignored the audio outputs may sound grainy and unpleasant low effects will result For more information see Word Length Reduction on page 104 Check the maximum input wordlength specification in the manual for the destination equipment You must set the dCS 974 to match this TOP LEVEL Sample Rate Conversion Audio Input Select Multi Channel Sync Default Default Default Top Hat Triangular NS Triangular Figure 5 Setting Wordlength Noise Shaping and Dither Scroll down the Sample Rate Conversion menu to Output Wordlength and press the button Scroll down the list to the required number of output bits and press Set Scroll down the Sample Rate Conversion menu to Noise Shaping and press the button From the list below choose a suitable setting to match the Output Wordlength e for 22 or 23 bits scroll to 2nd order and press Set e for 20 or 21 bits scroll to 3rd order and press Set e for 16 17 18 or 1 bits scroll to 9th ord
125. titive Trigger Mode Edge E 2 496 Figure 25 AES3 in to AES3 out 96 kS s fe running 1 2 90 Wediv H lim 4 500 10 00 1 ia de E re ate be is om a z s a ne a x F a A k is x A S Seen ZS a a d Nae S x a a Be Oe E Ae e e NU E 2 2 00 wdi pos 4 000 10 00 1 Ms de 2 5000 us O 000 g 2 J000 Us 200 ns div repetitive Trigger Mode Edge Er 2 496 VM Figure 26 AES3 in to AES3 out 44 1 kS s dCS 974 User Manual dCs Ltd Manual for Software Version 1 0x May 2001 DSD data out is aligned to Wordclock transitions as below the wordclock edges align with the data transitions rather than in the middle of the data eye If you need them the other way round use an additional 10m of cable in the WCLK OUT path Zoo running 1 2 90 diw BA lim 2 500 VM 1 000 1 308 de 2 2 00 Vrdi pos 2 000 1 000 7 30s de 1 0000 us O 000 zs 1 0000 us 200 ns div repetitive Trigger Mode Edge 2 ff 2 250 VM Figure 27 DSD data and Wordclock out dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Multiple Channel Sync ing Multiple channel sync ing requires more things to be in sync than two channel work the PLL must not be dual modulus the DSP algorithm must load with a constant group delay and the frame and block syncs must agree The dCS 974 meets all these constraints with the addition of a syncing signal transmitted from a master unit to s
126. ty gain i e OdB Balance is lit if the channel balance is shifted from centre Unlocked is lit if the unit is not locked to a valid digital input Rotary encoder Turn the Knob to move up down the menu tree adjust parameter values or edit store names You may select whether clockwise rotation moves the cursor up or down see the section on Display Customise page 50 The unit is shipped with the cursor moving downwards by clockwise rotation of the knob and all instructions in this manual refer to a unit in this configuration We recommend turning the knob at a steady speed rather than trying to turn it as fast as possible dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 dCS 974 TECHNICAL INFORMATION Digital Data Formats Supported dCS 974 provides nine digital data i o formats AES EBU often referred to as AES3 for PCM operation Dual AES part of the AES3 spec for PCM operation Quad AES part of the AES3 spec for PCM operation SDIF 2 for PCM operation SDIF 2 for DSD operation SDIF 3 for DSD operation DSD Quad for DSD operation SPDIF electrical for PCM operation SPDIF optical for PCM operation For all formats the incoming Channel Status and User messages are discarded The unit allows the AES EBU and SPDIF output Channel Status bits to be edited The enhanced AES EBU interface is fully implemented Each channel has its own parity and data validity bit as well as User and Channel Status mes
127. ual For the formal definition of the AES3 interface see footnote from the AES 2 AES3 1992 ANSI S4 40 1992 AES Recommended practice for digital audio engineering Serial transmission format for two channel linearly represented digital audio data dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 SPDIF Message Handling The SPDIF interface sometimes Known as the Consumer AES EBU interface transmits a data structure that conforms to the IEC 958 standard Like the AES EBU this contains 28 bits of Manchester encoded data and a 4 bit near Manchester encoded preamble in a subframe and subframes are further assembled in a block and frame structure The difference lies only in the voltage levels and the Channel Status bits the System Message It contains 24 bits of audio data IMPORTANT The AES EBU interface and the SPDIF interface have similar data structures although the messages are completely different The two structures are identified in the data domain by the use of the Consumer Professional bit bit 1 in the message A I indicates AES EBU format a 0 indicates SPDIF format The default SPDIF message attached to the output data by the unit before being changed by the user is as follows Professional Off Non Audio Off Copy Permit On Format 2 Channel General Format See EN 60958 1995 or IEC 958 1989 with amendments 1 amp 2 The structure of the message is sufficiently comple
128. ual for Software Version 1 0x dCs Ltd May 2001 Fixed Setups In addition to the 12 user setups there are 12 fixed setups which cannot be changed These are contained in the software and may be added to in future software updates Store A AES1 Au gt 24 44 Contains default settings Auto input on AES1 sync to Audio Input 24 bits 44 1kS s output in Normal mode If you get the unit into a tangle recall this and sort things out Store B DA Au gt CD N9 F2 Auto Dual AES input to CD format 9th order Noise Shaping Filter 2 Detect silence On Gain set to 0 1 0B Store C QA Au gt CD N9 F2 Auto Quad AES input to CD format 9th order Noise Shaping Filter 2 Detect silence On Gain set to O 1dB Store D DSD2 gt CD N9 F2 DSD SDIF 2 input to CD format 9th order Noise Shaping Filter 2 Detect silence On Gain set to O 1CB Store E AES1 Au MC gt DSD2 Auto input on AES1 Multi Channel Sync On to DSD SDIF 2 Filter 5 Store F AES1 Au MC gt 24 96 Auto input on AES1 Multi Channel Sync On to 24 96 single wire Store G AES1 Au gt 192DA Auto input on AES1 to 24 192 Dual AES Store H AES1 Au gt DSD2 F5 Auto input on AES1 to DSD SDIF 2 Filter 5 Store QA Au gt DSD2 F5 Auto Quad AES input to DSD SDIF 2 Filter 5 Store J DA Au gt 24 96 Auto Dual AES input to single wire 24 96 Store K AES1 Au gt CD N9F2 Auto input on AES1 to CD format 9th order Noise Shaping Filter 2 Detect silence On Gain set to O 1CB Store L AES1 Au FC gt
129. ubsequent slave units To do this it passes information in the User Bits of the AES3 message To slave adequately units must have this sync information input to the AES Ref Loop Input via a sync link Each slave will generate a copy based on its own timing for transmission to the next unit in the chain If the Multi channel Sync option is set to On in the Sample Rate Conversion menu any units with no user bit synchronisation data into its AES Ref Loop Input will become a Master If user bit synchronisation information is fed in it will become a slave Either unit will output synchronisation information via its AES CLK Output A master clock dCS 992 19 can be used as the master if more than about 8 channels are being used this system is best as it avoids any tolerance build up Connections are shown in the multi channel syncing applications starting on page 29 Using the multi channel sync mode the timing of the data at the output of the dCS 974 is related to the data coming in If three dCS 974 units are used in a six channel set up and the data into all of them is bit sync d from say a six channel source the outputs will be bit sync d If the inputs are not quite bit aligned then the outputs will not quite be bit aligned If the inputs are way off in phase but frequency locked the outputs will be way off in phase but frequency locked and the timing of the block structures of the several output signals will not be defined S
130. uency kHz Figure 37 DSD Output integrated Q Noise for the various Filter options dCS 974 User Manual Manual for Software Version 1 0x dCS Ltd May 2001 Spot Q Noise for DSD Filters F Weighted in 400 Hz bandwidth 80 20 F1 gag aa eles F2 H 120 V R 20 i F4 o 140 GC e 40 a ATAN S E A 160 l N F6 60 F PS D g iy F7 D 2 180 Mr Pe 80 2 o ee aa pom F weighting curve D z right hand scale g o 200 100 E O Z O 220 120 240 140 260 160 280 180 0 1 1 10 100 1000 Frequency kHz Figure 38 DSD Output F weighted Q Noise for the various Filter options DSD Format showing Full Scale Signal dCS 972 SW v1 54 1 5 1 0 5 0 0 5 1 1 5 0 50 100 150 200 250 300 350 400 450 Time usecs Figure 39 DSD showing 0 dBO full scale DSD has only two levels printer artefacts make it look like more 500 dCS 974 User Manual dCS Ltd Zoomed Passband Response dB Zoomed Passband Response dB 0 100 0 075 0 050 0 025 0 000 0 025 0 050 0 075 0 100 0 125 0 150 0 175 0 200 0 225 0 250 0 275 0 300 0 100 0 075 0 050 0 025 0 000 0 025 0 050 0 075 0 100 0 125 0 150 0 175 0 200 0 225 0 250 0 275 0 300 Manual for Software Version 1 0x May 2001 48 kS s to 44 1 kS s Filters dCS 972 SW v1 54 A bo aN 0 4 41 4 41 Filt 1 Filt 2 8 82 13 23 17 64 22 05
131. ut obtaining a Service Return number as this will delay the repair You may also incur costs if the unit is found to have no fault When returning a unit the original packing should be used to avoid transit damage Replacement packaging sets may be purchased from dCs During the Warranty period there will normally be no charge for repair or replacement dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Update or Calibration You may wish to have your unit updated occasionally dCS offer this service we will install any modifications or updates that have occurred since your unit was first shipped and give the unit a full retest to current standards The price will depend on the hardware changes necessary so contact your dealer or us In order to ensure speedy turn around please contact us prior to returning the unit Safety and Electrical Safety There are no user serviceable parts inside the dCS 974 and so there is no need to remove the covers apart from front panel software updates If for some reason you do IMPORTANT Disconnect from the mains before removing any covers or changing the fuse There are no substances hazardous to health inside the dCS 974 dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 TROUBLESHOOTING FAQs The unit fails to lock to a source signal e Check that Audio Input Select is set to the correct input e Check that Inout Sample Rate is either set to A
132. uto or set to suit the source device e Check that Sync Source is set correctly try setting it to Audio Input e Check for damaged cables The unit locks but no signal is received e Display the Bit Activity Monitor to see if a signal is available at the unit If there is no signal into the unit and Detect Silence is on there will be no signal out even with Dither and Noise Shaping on e If the unit is locked to an external clock check that Audio Input Select is set to the correct input e If SDIF 2 is used check that CH1 IN and CH2 IN upper block are both connected The destination device fails to lock to the unit e Check that the unit is locked to a source e Check that Output Sample Rate and Output Mode suit the settings on the destination device e Ensure the destination device is set to sync to the dCS 974 and not to a Master Clock e Ensure the destination device is capable of locking to the selected Output Sample Rate e Check for damaged cables The destination device locks but no signal or just noise is received e Display the Level Meters to ensure signal is present on the outputs e Check that the est Generator is off by pressing the Status button e Ensure the destination device is set to sync to the dCS 974 and not to a Master Clock The destination device connected to the AES or SPDIF outputs reports an error e Check that AES and SPDIF Messages are correctly set up e Check for damaged cables
133. vel menu select Bit Activity Monitor and press Set or Status With a substantial 20 bit input signal the display will be similar to this Bit Activity Monitor Re e LARS dezkzk BS kk kkk kk ER 15 T A The display is updated approximately three times per second The Display Timeout function is disabled while the Bit Activity Monitor is being used dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Level Meters Submenu Level Meter Overview The Level Meters monitor the Left and Right output signal levels They work on all PCM signals and can be used to monitor DSDby setting a DSD to PCM conversion The dCS 974 can be used purely as a programmable meter Because the meters work on the output data the filters can be used to change the bandwidth of the meters For example they can be used to monitor 96kS s data with a 20kHz bandwidth by setting the output rate to 44 1kS s or the full bandwidth can be examined by setting the output rate to 96kS s The Display Timeout function is disabled while the Level Meters are being used Turning the Level Meters On To access the Meters return to the top level menu select Leve Meters and press Set or Status With an input signal applied the display will look similar to this In 32 uses Oat 44 1 k 5s SSS db co 7h i 8 5 2 d emm pm Em GT TT The bar consists of 27 segments each representing 1dB The dashed segments at the right e
134. x that it is best to read the source material dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 SDIF 2 Message Handling The SDIF 2 interface is a 4 wire NRZ interface so the DC level on each signal line may not be constant It contains 20 bits of audio data and has a block structure of 256 stereo samples rather than the 192 of AES EBU There are 8 bits of message per channel per sample with a further 3 bits being used for an illegal code based sync code Of the 8 bits per sample the 8 in the first sample are reserved for system messaging and the rest are for User messages The 4 wires are Ground return Left Channel Right Channel Wordclock The sync codes enable data recovery without the word clock if necessary but with the number of data formats in current operation this method of locking is strongly discouraged The SDIF 2 message is given in the table following The dCs 974 implementation sets all bits of the User message to 0 DESCRIPTION Definition Default Message Undefined 0000 Oxxx 0000 Oxxx Emphasis No emphasis Xxxx x00x OC X00x Emphasis 15usec 50sec XXXX X01X Dubbing Prohibit Dubbing allowed XXXX XXXO XXXX XXXO Dubbing inhibited XXXX XXX1 Block Code Start of block XXXX XXXX 1 as required Not start of block XXXX XXXX Q as required Table 15 SDIF 2 Message Table SDIF 3 Message Handling At present no messaging is implemented in SDIF 3 dCS 974 User Manual M
135. y be set to operate synchronously using the sync link connections shown above from one units AES CLK Out to the next unit s AES Ref Loop In For all units set the Multiole Channel Sync option to On The top unit will set up as a master the other ones will set up as slaves Make sure that all the other settings are the same on each unit see the section Multiple Channel Sync ing page 81 for how aligned is bit aligned These are set up for PCM in to DSD out in Store E and for PCM in to 96kS s out in Store F dCS 974 User Manual Manual for Software Version 1 0x dCs Ltd May 2001 Multi channel Sample Rate Conversion Using a Master Clock 44 1kS s WORDCLOCK Te TO RECORDER 96kS s Ch1 amp 2 SS ese SS S Se ee EE S 96kS s Ch3 amp 4 e 44 1kS s SOURCE S 96kS s See Ch5 amp 6 e Q o 96kS s Ch7 amp 8 Figure 14 Multi channel Sample Rate Conversion with Master Clock You can use a dCS 992 Master Clock to sync up the source and be the master The sync link cabling starts from the master clock cable A and then carries on down units as shown Use of the master clock allows more units to be used together 24 channels worth or more For all dCS 974 units set the Multiple Channel Sync option to On They will all set up as slaves Make sure that all the other settings are the same on each unit version 2 0 or higher software dCS 974 User Manual Manual for Software Version 1 0x dCs Lt

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