USER MANUAL
Contents
1. Lr Fs re 8 5 mm eco L s s L zo e ezo mem Se IC zzo _ 829 mannnnnnnnnnnr nangnnnnnnnnn in esu eso Cer IUUUUUUUUUUUTUU nangnnnnnnnnnn ein abek nnnnnnmnnrni Lies un IUUUUUUUUUUUTUU St Cen sn E suk sp a Corto c7 2 CH E i ups Jot ues e S la UU rel Cen TC ES u 20 a 15 0 tral S E a r sou e nnnnnn in UUUUUU n oOo Oo B cL Z5 co cea TUTUTUUTUU 8 UUUUU Loy ou lt a o amer D E E Soa 01133 Cha 115VAC 230VAC power switch DIC Tl Amp 20mm Slow Blow fuse Typical Setup Balanced signal source Stereo96 ADC 1s equipped with 2 XLR analog inputs For best signal to noise performance it is recommended the signal source has a typical low impedance output with standard 4dB line level balanced signal Alternatively a weaker unbalanced signal source can be used as described in subsequent paragraph In typical setup the ADC is running on its internal clock with the rest of equipment synchronized to Mytek clock either through digital output2. The two higher sampling rates are recommended for discerning users requiring uncompromised sound quality In this mode the ADC features a 40kHz bandwidth instead of 20k which allows for improved transient response of recorded music as well as minimized the impact of brick wall antialiasing digital filters on the upper audio band The end effect of hi sampling recording is a more analog feel and easiness of sound and more natural sounding instruments especially percussion or cymbals A decision of choice btwn 88 2k or 96k should be made based on the project flow there might be arguments for one or the other For example 88 2k may convert to 44 1k with less damaging SRC process if such process is available Most ubiquitous software SRCs are not very good 12 and must not be used for critical projects downsampling Some such as Faulkner Downsampler http www audiosignal co uk freeware html provide excellent results for 88 2 gt 44 1 but don t work for 96k 88 2k is also easier to upsample to DSD 96k sample rate has in our opinion a marginally better perceived sound quality than 88 2k but the difference is very small and difficult to perceive for most people If the record is going to be mixed in analog domain 96k might be a desirable choice for tracking 13 Mytek SuperShaper HR TM Noise Shaping and Dither The Stereo96 A D converter employs SuperShaper HR a sophisticated psychoacoustically optimized noise shaping
3. The theory and practice of selecting high sample rates such as 96kHz and word lengths of up to 24 bits are examined The relative importance of sampling rate and word size at various points in the recording mastering transmission and replay chain 1s discussed Dynamic Range Enhancement Using Noise Shaped Dither at 44 1 48 and 96 kHz Preprint Number 4236 Convention 100 1996 05 Author J R Stuart Author R J Wilson This paper presents an overview of the work done on noise shaping summarizing how noise shapers are designed implemented and measured and outlining the hearing model used to evaluate the various designs achieved Dynamic Range Enhancement Using Noise Shaped Dither Applied to Signals with and without Preemphasis Preprint Number 3871 Convention 96 1994 03 Author Robert Stuart Author Rhonda J Wilson This paper presents new noise shaped dithers designed to give increased subjective dynamic range when applied to signals with and without pre emphasis 15 Optimal Noise Shaping and Dither of Digital Signals Preprint Number 2822 Convention 87 1989 10 Author Michael Gerzon Author Peter G Craven This paper discusses optimizing noise shaping with or without dither using filtered error feedback round a quantizer Psychoacoustically Optimal Noise Shaping Preprint Number 2965 Convention 89 1990 09 AES Journal Vol Issue 40 7 8 Page 611 Year 1992 Author Robert A Wannamaker
4. It s not recommended to peak frequently although occasional overloads might be acceptable Analog Input Alignment When using internal trimpots analog input level needs to be aligned using an approx 1kHz sinewave fed from 4dB balanced source The alignment does not affect audio quality only input sensitivity The alignment is performed using 10 turn trimpots inside the unit see Internal Jumpers A small tweaker or screwdriver is necessary You have to arbitrarily decide what will be your studio 0 VU analog digital reference level It is usually between 20 and 14dB It defines how much headroom you have left over the normal operating 0 VU level You may set it at the same level as other piece of equipment in your studio For example Panasonic 3700 is fixed at 18dB which is low for most rock and roll recordings ADAT is fixed at 15dB which is a typical optimal level 1 Set the oscillator in your console at 1kHz and 0 VU Send the oscillator to the ADC analog input 0 VU at AdB corresponds to 1 225 Volts RMS measured between pin 2 and 3 of the output XLRs If you do not have an analog oscillator you can use a calibrated analog out of a DA converter and generate the sinewave inside the DAW 2 Connect a digital PEAK meter to a digital output If you don t have a dedicated digital meter use the most precise meter available in you existing digital recording equipment or DAW 3 Adjust the analog input level to get appropriat
5. This paper examines the design of psycho acoustically optimal noise shaping filters for requantization in non oversampling digital audio applications 16 Rack Mount Shelf The Stereo96 ADC is 1 3 rack space wide and 1U tall Mytek provides a 1U rack mount shelf as accessory to mount up to 3 of 1 3 rack units The units are attached to shelf with small screw connecting the shelf to bottom through a threaded hole on the bottom of the unit 17 Companion Stereo96 DAC this page will be updated 18 Conversion Resolution Sample rates Dynamic Range THD Noise Internal clock jitter Analog Inputs Digital outputs External Sync Wordlock Out used as house clock Mains Dimensions Weight Specifications Linear 128x oversampling at 44 1 48kHz 64x oversampling at 88 2 96kHz 24 bit 44 1kHz 48kHz 88 2kHz 96kHz or wordclock 25 100kHz 120dB A weighted 117dB Total 105dB lt 0 0005 lt 10picoseconds 4dBm balanced or unbalanced 10kOhm Hi speed 25 100kHz AES EBU and SPDIF Wordclock in and out or 256x Superclock 15 LS TTL loads max Can be terminated 100 115V 220 240V 50 60Hz switchable 1 3 rack space wide x 1U high x 8 deep 5 5 x 1 6 x 8 4 pounds 19 Warranty This Stereo96ADC digital audio converter is warranted by Mytek to the original purchaser against defects in workmanship and materials used in manufacture for a period of one year from the date of pu
6. and dithering algorithm SuperShaper HR uses 9th order high resolution noise shaping filters with proprietary filter coefficients developed by Mytek Inc The appropriate noiseshaping curve is programmed into noiseshaping filters This feature allows for preserving most of 24 bit performance in 16 bit data output 60dB 50dB 40dB 30dB 20dB 10dB 0dB 10dB 20dB 30dB 40dB OHZ 5k 10k 15k 20k 25k Noise shaper performance graphs at 16 bit output When noise shaping processing is on the quantization noise is removed from the audio band where the noise floor is kept as close as possible to the 24 bit level and moved to the 20 22 kHz range The noise shaping filters are automatically engaged at appropriate levels when 16 bit output marked Supershaper HR is selected If 24 or 20 bit bit output is selected the noise shaping filter is off 14 More information about use of noise shaping in high resolution recording can be found in the following Audio Engineering Society Preprints http www aes org Coding Methods for High Resolution Recording Systems Preprint Number 4639 Convention 103 1997 09 Author J Robert Stuart This paper reviews the recording and reproduction chain from the viewpoints of digital audio engineering and psychoacoustics It also attempts to define the audio requirements of a transparent digital audio channel
7. signal or wordclock In this configuration Mytek ADC serves as a very stable low jitter house clock which increases the integrity and robustness of the rest of the system Because of careful design this clock is as good or better than dedicated studio clock generators Unlike in lesser quality equipment there is no sonic benefit in clocking Mytek ADC externally In case of such operational need refer to Sampling frequencies and external synchronization Setup for typical balanced operation includes following steps 1 Setup the unit using external jumpers to a Balanced inputs fed through input knob factory default This mode is recommended for casual use where the input level is vaguely defined and needs to be quickly adjusted with input knob or b Set the jumpers to balanced inputs fed through precision 10 turn trimpots Then perform analog input alignment as described in the next chapter 2 Setup all other connections 3 Select desired clock source sync either internal or external If external wordclock or superclock source is required for systemic reasons setup its mode using the DIP switch as described in Internal jumpers The wordclock source can be terminated with internal 75 Ohm resistor inside the Mytek unit see Internal jumpers The termination is recommended when using long wordclock cables above 10 ft and when the wordclock source is capable handling such termination Do not terminate if the source is no
8. MYTEK DIGITAL USA VOLUME STEREO96 ADC MVIEK DIGITAL USA O Super OO Os worn Q6 Y O70 Can LENGTH C0 sync Osa O 200 Qa e Qa e Ow O O MASTERING ANALOG TO DIGITAL CONVERTER USER MANUAL VER 5 2005 This manual may be updated Download the newest version at http www mytekdigital com manuals stereo96adc_manual pdf For technical support technical tips and support check http www mytekdigital com products stereo96adc htm or contact Mytek tech support at info2005 mytekdigital com or at tel 646 613 1822 fax 212 202 5331 Mytek 151 Lafayette Street 3rd Fl New York NY 10013 USA Quick Start oo EE ee oo dE E A SEES 3 Introduction i u rne prre ur Pe ote eint 4 Operation Internal jumper settnges sse 5 Operation Typical setup Balanced Signal Source 7 Operation Analog input alignment nnneeeeeeeeen 9 Operation Unbalanced Signal Source 10 Sampling frequencies and External synchronization 12 SuperShaper HR TM Noise shaping and dithering 14 Rack mount shelf oni Uh Here Rer edis 17 Companion Stereo96 DAC 18 SpecifiCatiOris 205 sos ide Eve EENS 19 Warranty conditions eens enenens 20 Input volume knob sets the input Sample rate selection sensitivity with range from mute to Sets the desired 4dB 10dBFS This is factory sample rate When default The knob can be disabled used with external clock with internal jumper
9. d to peak frequently although occasional overloads might be acceptable 11 Sampling frequencies and External Synchronization In typical setup the ADC is running on its internal clock with the rest of equipment synchronized to Mytek clock either through digital output signal or wordclock In this configuration Mytek ADC serves as a very stable low jitter house clock which increases the integrity and robustness of the rest of the system Because of careful design this clock is as good or better than dedicated studio clock generators Unlike in lesser quality equipment there is no sonic benefit in clocking Mytek ADC externally Mytek internal clock generator is situated within inches of converter chip and it will always provide a better jitter performance approx 10ps than any external source which is inherently compromised by cable connections If external wordclock or superclock source has to be used for systemic reasons the Stereo96ADC clock generator will lock to external source and use a stabilizing PLL circuit to reduce incoming clock jitter before it reaches the actual AD circuit Stereo96A DC can be operated with any of 4 standard sampling frequencies or at any frequency btwn 30k 100k when supplied with external clock source The measurable audio band performance Dynamic Range stays virtually the same within all these frequencies 44 1k will be typically used for printing final master 48k is recommended for digital video production
10. e reading of the meter for example 15dB The alignment has to be performed with accuracy of 0 1dB to be considered accurate Similar alignment procedure with 0 1dB accuracy is required for valid A B listening comparisons btwn different pieces of equipment A slightly louder source is typically perceived as better sounding Unbalanced Signal Source Operation Stereo96ADC can be operated with weaker consumer level unbalanced signal sources Follow these steps in such case 1 Unbalanced cable used to feed the unit must have signal connected to pin 2 of XLR ground shield connected to pin 1 and while 3 must be disconnected Wrong wiring of this cable can cause improper operation resulting in elevated distortion or noise 2 Set the jumpers to unbalanced and disconnect both the trimpots and potentiometer This sets the converter to its hights sensitivity approx 10dB FS 3 Setup all other connections 4 Select desired clock source sync either internal or extrenal If external wordclock or superclock source 1s required for systemic reasons setup its mode using the DIP switch as described in Internal jumpers The wordclock source can be terminated with internal 75 Ohm resistor inside the Mytek unit see Internal jumpers The termination is recommended when using long wordclock cables above 10 ft and when the wordclock source is capable handling such termination Do no terminate if the source is not capable of hig
11. h current drive or cable is short 4 Select sampling frequency If wordclock superclock is used the sampling frequency has to correspond to external clock frequency can be multiple see Internal jumpers 5 Select output wordlength 24 bit full output is recommended 16 and 20 bit output are meant to be used when the destination recorder such as CDR ADAT tape machine limits the wordlength 20 bit output is dithered with flat dither 16 bit output can either be dithered flat recommended for multitrack recording or 16 bit noiseshaped recommended for final masters printing to CDR or DAT machine 10 The Supershaper HR tm used for 16 bit wordlength reduction is a sophisticated 9th order noise shaper with dither similar in operation to Pow r 3 tm noise reduction algorithm see Supershaper HR 6 Synchronize the destination either to digital input sync or to wordclock sync depending on system configuration The quality of recorded signal does not depend on how the digital destination is synchronized with Mytek AD converter 7 Record adjust input level by adjusting level at the source Unless you are printing final CD master we do not recommend recording too hot There is no sonic benefit of pushing the level up to OdBFS A healthy 1 2 3 dBs headroom allows more freedom in later processing and mixing of recorded tracks The red peak light is triggered digitally when 1 or more samples are overload It s not recommende
12. ng sound quality The sound of Mytek converters can be described as transparent We design our converters to be as faithful to the signal as possible rather than the philosophy of some other manufacturers who offer analog or tube sounding converters Mytek converters are closest to a straight wire which is especially evident when used at full 24 96 resolution Sonically they are equal or better than the most expensive mastering converters Even when used in 16 bit mode the Stereo96 converters produce 20dB 10 times less distortion than typical converters found in budget recording equipment On Mytek website you can find and download various sound samples to evaluate Stereo96 series sound quality and compare it to the sound of other high end converter units To download samples log onto http www mytekdigital com listening tests htm Stereo96 ADC features include 44 1 48 88 2 and 96kHz internal sampling frequencies Ext wordclock sync 25 100kHz or 256x Superclock tm 120dB Dynamic Range 24 bit resolution High performance SuperShaper HR psychoacoustic noiseshaping algorithm for 16 bit output Switchable precision 10 turn trimpots or input gain knob Wordclock output can be used as a hi end house clock Stereo96ADC internal trimpots and jumper assignments remove top cover to access Jumper JP5 Wordclock input 75 Ohm termination Connect this jumper when Stereo96 ADC is the last destination in a chain fed b
13. r most of other digital equipment or 18 to comply with AES level standard Refer to Analog input level Chapter for alignment procedure details These jumpers should normally be removed retain the jumper on pin only if input potentiometer is engaged but can also be used in parallel with the pot using both pot and trimpots will result in lower input sensitivity with advantage of precise L R matching JP2 and JP4 Balanced input at 4dBm professional level JP2 and JP4 these jumpers insert the input volume conductive plastic potentiometer for both left and right analog inputs this setting mimics a typical DAT machine input volume knob and can be used for remote recording and other applications where the input level is vaguely defined and needs to be instantly adjusted The pot also allows for live fade in and out The pot is not recommended for regular studio use as the L R sensitivity cannot be set as precisely as with trimpots because of the mechanical accuracy of the pot These jumpers should normally be removed retain the jumper on one pin only if trimpots are engaged although parallel operation is possible see above Stereo96ADC internal trimpots and jumper assignments remove top cover to access 89
14. rchase Faults due to customer misuse unauthorized modifications or accidents are not covered by this warranty No other warranty is expressed or implied Any faulty unit should be sent shipping prepaid to the manufacturer service center Prior to shipping the client should obtain from Mytek an RMA for warranty services Units sent without RMA will not be accepted Mytek extends affordable repair service for all units manufactured to date that are not covered by this Warranty 20
15. s which can select either the knob or internal select FS closest matching that of precision 10 turn trimpots Refer to supplied external Internal jumper settings for details wordclock Peak meter in dBFS The red LED marked 0 corresponds to 1 sample overload STEREO96 ADC wrrbenmcuss O Ois Super Shaper HR Oss p Onna 6 O 3 O O CH O20 e Ow O 20 Qa Ow QO O Selects output wordlength as stated The 20 and 16 bit flat dither setting corresponds to signal dithered with flat dither Supershaper HR is a high performace wordlength reduction algorithm similar to Pow r tm Flat dither is recommended for multitracking while Supershaper can be used for printing final mix to CD R Internal sync provides the best clock stability 10ps and thus the best conversion External sync is intended for complex systems It can be a standard wordclock signal or Protools tm 256X superclock Refer to Internal jumper settings for details Since internal clock generator is top notch there is no sonic benefit from clocking Stereo96ADC externally Line power is 115VAC 50 60Hz Wordclock input factory default Analog inputs accept a factory default or can be set to alternatively accept range of signals from 4dB 230VAC 50 60Hz switchable by 256 Protools tm Superclock Mix balanced down to internal switch accessible after systems Refer to Internal jumper consumer unbalanced removing the top cover 1 Amp set
16. t capable of high current drive or cable is short 4 Select sampling frequency If wordclock superclock is used the sampling frequency has to correspond to external clock frequency can be multiple see Internal jumpers 5 Select output wordlength 24 bit full output is recommended 16 and 20 bit output are meant to be used when the destination recorder such as CDR ADAT tape machine limits the wordlength 20 bit output is dithered with flat dither 16 bit output can either be dithered flat recommended for multitrack recording or 16 bit noiseshaped recommended for final masters printing to CDR or DAT machine The Supershaper HR tm used for 16 bit wordlenght reduction is a sophisticated 9th order noise shaper with dither similar in operation to Pow r 3 tm noise reduction algorithm see Supershaper HR 6 Synchronize the destination either to digital input syne or to wordclock sync depending on system configuration The quality of recorded signal does not depend on how the digital destination is synchronized with Mytek AD converter 7 Record adjust input level with knob or by adjusting level at the source Unless you are printing final CD master we do not recommend recording too hot There is no sonic benefit of pushing the level up to OdBFS A healthy 1 2 3 dBs headroom allows more freedom in later processing and mixing of recorded tracks The red peak light is triggered digitally when 1 or more samples are overload
17. tings for details 75 Ohm slow blow 20mm fuse is also accessible under the cover set inside unit IN Refer to Internal jumper termination default off can also be settings for details AES OUT et 110 220VAC WCK SUPERCK OUT SWITCH AND FUSE INSIDE SWITCH INSIDE Wordclock output provides high current drive and a very stable low jitter clock It can be used as a superior house clock to clock or synchronize other digital equipment Running Stereo96ADC on internal clock and slaving the rest of equipment to Mytek clock is the recommended setting for best sonic performance WWW MYTEKDIGITAL COM AES EBU and SPDIF outputs are simultaneous They operate in single wire mode for all sampling frequencies These outputs can be used to externally clock other equipment with the same effect as wordclock output Clocking via AES EBU line is recommended especially when cables are very long over 20ft Introduction to Stereo96 Series Converters The MYTEK Stereo96 series consists of two 1 3 rack units the Stereo96 ADC and the Stereo 96 DAC They are also a part of extended family of 1 3 rack units which also includes 192kHz capable converters SRC and Studio Clock Stereo96 converters can be used as stand alone devices for variety of studio applications such as mastering recording and playback whenever the highest quality conversion is required Users choose Mytek 8X96 converters primarily for their outstandi
18. y external wordclock source and the cable is long above 6ft For short cables and wordclock sources with unknown drive capability JP5 should be left unconnected unterminated retain the jumper on one pin only DIPSWITCH SWA Sets the clock mode on BNC in out SWI ON wordclock FS 2 for 88 2 and 96k FS for 44 1 and 48k SW1 OFF wordclock FS for all sampling rates SW2 ON output and input becomes Superclock 256 x FS for use with Protools R Mix systems and 44 1 and 48k only Jumpers J1 and J2 Set the input to unbalanced The unbalanced signal should be fed between pin 2 signal and pin 1 shield of the input XLR Pin 3 must be left unconnected You can use a standard RCA lt gt XLR adapter but make sure connection to pin 3 is cut inside the adapter Jumpers JP2 JP4 JP1 JP3 should be removed retain the jumper on one pin only In this mode the sensitivity of the input stage 1s fixed and cannot be adjusted within the converter adjust level prior to feeding the converter This mode is recommended only in situations when no professional balanced signal source is available This also works with 10dBV consumer level JP1 and JP3 Balanced input at 4dBm professional level JP1 and JP3 these jumpers insert the 10 turn precision trimpots RN2 and RN3 for both left and right analog inputs These trimpots determine the 4dBm headroom of the ADC The setting can be anywhere from 14dBFS to 20dBFS typical being 15 or 16 fo
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