Grace M201 User's Manual
Contents
1. 120V 120V 250V T 500mA L 220V 220V 250V T 250mA L 240V 230V 250V T 250mA 240V 240V 250V T 250mA lt figure 2 fuse value table gt CHECK LINE VOLTAGE SETTINGS Your m201 has been set from the factory to operate at the voltage required for your part of the world However it s important to double check this in order to ensure no damage will come to the unit if power is applied while the setting is incorrect Preamplifier Operation TURNING THE POWER ON The power switch is located on the m201 front panel Pushing the power switch in turns the mains power on switch illuminates green Pushing the power switch again turns the mains power off USING THE INPUT MODE SELECTOR SWITCH The input mode switch to the right of the gain control provides a convenient way for the user to select between the various types of inputs the m201 can accommodate The following in an overview of the four settings 48V This setting should be selected for all general recording applications with most microphone types In this position the main XLR mic inputs are feeding the preampli fier and the dual XLR outputs are active Proceed with the setting the gain discussion below HI Z This setting is used to select the front panel mounted 1 4 instrument DI inputs These inputs can accommodate a wide variety of high impedance input sources in cluding bass guitar keyboards electric guitars etc this mode the rear panel XLR2. 1kHz gt 80dB 10kHz gt 60dB IMD SMPTE 4 1 60Hz 7kHz 3dBFS lt 100dB 0 0008 Interchannel crosstalk lt 120dB Group delay 44 1 48kHz 13 Fs Sample rates internal crystal kHz 44 1 48 88 2 96 176 4 192 External Clock Lock Range Wide lock mode 40 1kHz 207kHz 8 at each sample rate s Lock mode 250ppm 350 400ppm typical Intrinsic Jitter 200Hz 20kHz BW Wide lock mode lt 60ps RMS s Lock mode lt 40ps RMS Jitter Rejection Corner Frequency Wide lock mode 3dB 12dB octave 800Hz s Lock mode 3dB 12dB octave 10Hz A D sensitivity Range 22dBu OdBFS 18dB Range B 18dBu OdBFS 14dB can be calibrated for any setting between 18dBu OdBFS and 24dBu OdBFS grace design m201 17 owner s manual Signal Flow Diagram INPUTS RIBBON 10dB 20dB 48 OFF ANALOG OUTPUTS GRACE DESIGN m201 SIGNAL FLOW DIAGRAM 4 CH10UTB HI Z INPUT MICROPHONE AMPLIFIER san ke MS OUTPUTS gt 130V _ gt 20dB gt MID l DPA INPUTS OPTIONAL SIDE i ud M S WIDTH RIBBON 10dB gt 48V gt 20dB gt 48 OFF RIGHT OUT 5 DIFFERENCE AMPLIFIER 2
3. Accomodates 130V DPA microphones via 4 pin XLR connectors Q Optional A D Converter module Optional A D converter module for the m201 includes seperate balanced analog A D line inputs 2x AES3 out puts single and dual wire word clock loop sync in and out S PDIF out and TOSLINK optical out grace design m201 5 owner s manual 6 Audio Connections Microphone input connections are made via female XLR connectors with pin 2 posi tive pin 3 negative and pin 1 ground 48V phantom power is supplied on pins 2 and 3 Output connections are made via male XLR connectors with pin 2 positive pin 3 negative and pin 1 ground If the output is to be used unbalanced pin 1 should be connected to signal ground and pin 2 to signal hot Due to the nature of the balanced output stage pin 3 should be left open for unbalanced operation See lt figure 1 gt below Note This will provide a signal of positive absolute polarity when the preamplifier is being used with a microphone which produces a positive voltage on pin 2 with positive air pres sure on the front of the diaphragm While a vast majority of microphones conform to this standard a few do not Use the phase reverse switch to compensate if necessary SHIELD figure 1 gt Unbalanced output cable termination To connect to the front panel HI Z input the input mode selector switch must be positioned in the HI Z location which changes the preamplifier input
4. Each of these are labeled on the A D module circuit board lt figure 3 gt 9 Locate the appropriate trimmer for the channel you wish to adjust If the current signal level is high you need to decrease the A D sensitivity Using a non conduc tive tool turn the appropriate trim pot counter clockwise to reduce the level until only the 0 is illuminated on the m201 meter If the current signal level is low you need to increase the A D sensitivity by turning the appropriate trim pot clockwise to increase the level until only the 0 is illuminated on the LED level meter grace design m201 owner s manual 10 Once all desired calibration adjustments have been made press and hold the INPUT SENS button for approximately 3 seconds This will exit CAL mode and re turn the A D to normal operation The new settings are now stored until future changes are made 11 Power down the unit disconnect the AC power and reinstall the top cover K4 CDt R22 25 C41 DT CH2 B 1 A VR2 CH2 A VR3 40 TPATTP5 TPS 5 15VA 6 5V 3 3V 40 O FRONT PANEL lt figure 3 A D sensitivity trim pot locations gt grace design m201 13 owner s manual 14 Maintenance The model m201 was designed to be maintenance free for many years It is highly unlikely that your unit will require service However there are two adjustments that may need to be made from time to
5. Front Panel Controls m eagv e ribbon e ribbon 10dB HI Z 1 INPUT MODE Q 24 position gold contact gain switch Each gain control has 24 positions and adjusts the volt age gain from 18dB to 64dB in 2dB steps In ribbon mode the gain range is 28dB to 7488 2dB steps bi color LED peak indicator The LED peak indicator which monitors the output sig nal level turns green at 14dB and switches to red at 16dB 12dB before clipping The threshold level for peak indication is adjustable on each channel see the calibration section of this manual input mode switch The input mode switch is used to select between the various types of inputs available with the m201 includ ing standard 48V ribbon mic mode HI Z or the optional 130V DPA inputs Refer to the m201 block diagram at the end of this manual for signal routing details 48V phantom power switch The phantom power switch labeled 48V connects the 48V power supply to pins 2 and 3 on the XLR in put connector This switch illuminates red It should be noted that the LED in this switch actually monitors the phantom power voltage at the input With no micro phone connected the LED will continue to illuminate for approximately 10 seconds after the phantom power is turned off as the filter capacitors discharge As well even if the phantom power is switched off the LED will illuminate if voltage is being fed from an ext
6. source from the mic input connector to the front panel TRS jack The input impedance of the in strument input is 2M Ohm balanced and 1M Ohm unbalanced which is ideal for inserting high impedance sources such as guitars with passive pickups as well as any instrument with a high level output Wiring of the HI Z jack is Tip positive Ring nega tive and Sleeve ground Please note that the gain range of the preamplifier when us ing the instrument input is 2dB to 48dB in 2dB steps Power Connections A standard three prong AC power cable is included with the m201 For safety the power supply cord must be connected to a grounded outlet The Disconnect Device for the m201 is the Mains plug or the Appliance Coupler on the power supply cord The Disconnect Device must remain accessible and operable AC input voltage settings can be adjusted for 100V 120V 220V and 240V operation at 50 60Hz If your line Voltage is 230VAC then use the 240V setting From the rear of the m201 open the trap door next to the IEC power inlet with a small screwdriver Care fully pull the voltage select cam straight out and then insert with the desired voltage grace design m201 owner s manual showing Do not try to rotate the cam while it is in the power input module Replace the fuses with the proper value selected from lt figure 2 gt below Be sure to use a time delay fuse with a 250V rating CAM SETTING LINE VOLTAGE FUSE VALUE 100V 100V 250V T 500mA
7. 5 9 gt 4 gt HI Z INPUT AMP MICROPHONE AMPLIFIER BALANCED OUTPUT DRIVERS gt 130V gt 20dB DPA INPUTS 5 OPTIONAL ADC INPUTS OPTIONAL ANALOG TO DIGITAL CONVERTER MODULE ADC INPUT SELECTOR FROM PREAMP CH 1 2 FROM M S OUTPUT DIGITAL OUTPUTS LINE IN LEFT LINE IN RIGHT WORD CLOCK LOOP SYNC IN WIDE RANGE PLL s Lock PLL INTERNAL CLOCK AES3 2 TOSLINK 2 CH SPDIF CLOCK OUT grace design m201 owner s manual 18 Warranty Information Q Grace Design warrants all of our products to be free of defective parts and work manship for a period of five years This warranty period begins at the original date of purchase and is transferable to any person who may subsequently purchase the product during this time This warranty excludes the following conditions normal wear and tear misuse customer negligence accidental damage unauthorized repair or modification cosmetic damage and damage incurred during shipment G During the time of this warranty Grace Design will repair or replace at its option any defective parts or repair defective workmanship without charge provided the customer has appropriate proof of purchase and that the product has its original factory serial number Qin order for Grace Design to provide efficient and timely warranty service it is important that you mail the complete
8. A D moduleinfrmation ____________ oo 20 grace design m201 owner s manual
9. C gt Fi amp gt a e 5 i 5 A EI 7 microphone preamplifier optional A D converter module manual Rev C owner s manual all contents 2007 Grace Design Lunatec LLC Welcome Thank you for purchasing the Grace Design m201 microphone preamplifier With the combination of unmatched sonic performance powerful features and solid reliability the m201 is a powerful recording tool designed to help you make the best recordings of your career We have designed the m201 to be as easy and intuitive to use as possible However we strongly recommend that you read this product manual thoroughly to familiarize yourself with the unique features and capabilities of the m201 Also please do not hesitate to contact us directly if you have any questions comments or concerns with your new m201 microphone preamplifier Thanks for reading and happy recording The Grace Design Team Contents Welcome Important Safety Information Front Panel Controls Rear Panel Connections Audio Connections Power Connections Preamplifier Operation Ribbon Mic Mode M S recording with the m201 The Optional A D Converter Features Operating The A D Converter Module A D Converter Sensitivity 11 Maintenance No ID iO IB W IN Cleaning Signal Flow Diagram Warranty Information Manual Revisions 2 grace de
10. LINE as the A D input source 6 To enter CAL mode press and hold the INPUT SENS button for approximately 3 seconds The normal operation displays will extinguish and the CAL indicator will begin flashing indicating CAL mode is active The current input sensitivity range A or B will be illuminated along with that range s current sensitivity calibration shown as dB Headroom in the bottom left of the meter display 7 Press and release the INPUT SENS button to select the range A or B that you wish to calibrate 8 Press and release the A D SOURCE button to scroll through the 4 available sensi tivities until the desired setting is illuminated In calibration mode the digital audio meter is configured such that the 0 position is the target sensitivity level The meter then indicates the current signal level versus this target sensitivity The meter will display a window centered around the target sensitiv ity with a 0 4dB width in 0 1dB increments When the sensitivity adjustment on the A D converter is calibrated for the selected setting only the O LED will be illumi nated If the signal level is high the 0 indicator will be illuminated along with the error in 0 1dB increments to the right of If the signal level is low the indicator will be illuminated along with the error in 0 1dB increments to the left of 0 On the m201 A D module trim pots are used to adjust the A and B ranges for each channel
11. d If the proper level can t be reached adjust the preamplifier gain control 10 Locate VR2A VR2B for channel 2 see figure 3 on the channel 1 audio circuit board and adjust until the peak LED is between green and red The color should appear amber when the setting is correct Repeat this procedure for channel 2 11 If it is desired to calibrate the peak indicator to a specific converter recorder input level simply connect the output of the preamplifer to the converter re corder Adjust the signal generator so that the desired peak level is indicated on the recorder and then adjust VR1 until the peak LED is between green and red INPUT OFFSET ADJUSTMENT grace design m201 owner s manual The input amplifiers in the m201 are ultra precision laser trimmed devices which have a very low input offset However even the smallest differential offset at the input can result in an audible click when the gain control is turned It should be noted that this type of click will be audible when no signal is present With no signal present there is no signal amplitude to be changed unless input offset is present This procedure nulls the input offset and minimizes the clicking sound with no signal present In contrast there will almost always be an audible click if turning the gain control while a signal is present This is because the gain control being a stepped control will make an instan taneous change in amplitude when turned which creat
12. d warranty registration card enclosed with all of our products within 10 days of the original date of purchase You may also register your product directly with Grace Design by telephone 303 443 7454 Monday Friday 9 00am to 5 00pm MST or you can register your product online at www gracedesign com OThis warranty is in lieu of all other warranties whether written expressed or implied INCLUDING ANY WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE Qln no event will Grace Design be liable for lost profits or any other incidental consequential or Exemplary damages even if Grace Design is aware of the possibility of such damages In no event will Grace Design s liability exceed the purchase price of the product This warranty gives the customer specific legal rights The customer may also have other rights which vary from state to state Some states do not allow limitations on implied warranties or consequential damages so some of the limitations of the above may not apply to a particular customer grace design m201 19 owner s manual Manual Revisions Revision change ______________ mitia o mmarmeme mes 87 13 eanged voltage range and power specications 04 26 2007 mbs fs 4 Power switch description changed to standby switch 04 26 2007 mb ___ power mains disconnect information 04 26 2007 mbs 13 added signal fow diagam c su Added
13. ency Response 40dB gain 0 2dB 500 source 18Hz 65kHz 40dB gain 3dB 500 source 4 5Hz 350kHz THD N 20dB gain 25dBu out 1kHz lt 0008 gain 25dBu out 1kHz lt 0009 60dB gain 25dBu out 1kHz lt 0070 Intermodulation Distortion gain 25dBu out SMPTE DIN 1 1 50Hz 7kHz 002096 SMPTE DIN 4 1 50Hz 7kHz 003096 Noise Referred to Input 60dB gain 500 source 130dB 60dB gain 1500 source 127dB 60dB gain 6000 source 123dB Phase Deviation 100Hz 20kHz 40 gain 3 Crosstalk Any Channel 40dB gain 1kHz 125dB Any Channel 4088 gain 10kHz 115dB CMRR 60dB gain 3 5Vcm 1kHz gt 70dB 60GB gain 3 5Vcm 10kHz gt 70dB Maximum Output Level 1kHz 100KQ load 28dBu Impedance Input 81000 Input ribbon mode 20kQ Output 1900 Peak Led Meter Green threshold 14dBu Red threshold 16dBu Weight and Dimensions dimensions 2U 19 rack mount x 10 deep weight 16 5165 7 5kg Power Consumption 100 120 230 240V 50 60Hz 20 Watts Max A D module specifications line input Dynamic range 20Hz 20kHz gt 115dB weighting gt 117dB THD N 1kHz 1dBFS 20Hz 22kHz lt 0 00026 112dB Frequency response 0 2dB 3dB 44 1kHz Fs 5Hz 21kHz 22kHz 48kHz Fs 5Hz 23kHz 24kHz 88 2kHz Fs 5Hz 41kHz 44kHz 96kHz Fs 5Hz 45kHz 48kHz 176 4kHz Fs 5Hz 54kHz 72 5kHz 192kHz Fs 5Hz 59kHz 79kHz Full scale input level 16dB or 24 2 trim CMRR 60Hz gt 65dB
14. ernal source i e when using a direct split in a remote recording ap plication Also the 48V switch is used to activate the 130V DPA mic power if this option is installed polarity reversal switch The polarity reverse switch reverses the absolute phase grace design m201 owner s manual e meo1 microphone preamplifier GRACE DESIGN USA of the music signal at the input of the preamplifier The switch illuminates green and provides power for a sealed gold contact relay located on the preamplifier circuit board This eliminates signal wiring to the front panel and switch contact performance problems The polarity reverse function is active for all input connec tors pad switch The 2088 attenuator switch attenuates the input signal 20dB The switch illuminates amber when engaged Like the phase reverse switch this switch controls a sealed gold contact relay on the preamplifier circuit board With the 20 switch engaged the effective gain range becomes 2dB to 44dB The 20dB attenuator is active for 48V Phantom ribbon and optional DPA in puts It does not affect the HI Z inputs Hi Z input This 1 4 inch TRS input is active when the input mode switch is in the HI Z position Suitable for any high impedance source such as bass guitar acoustic guitar electric guitar keyboards etc This input is can be used balanced with a TRS connector or unbalanced with a TS connector M S width contr
15. es Dooley and Don Streicher called M S Stereo A Powerful Tech nique for Working in Stereo This paper No 1792 is available from the Audio Engi neering Society web page www aes org The Optional A D Converter Features A B s FS SELECT CLOCK SOURCE ADC MODE J 60 50 40 32 28 24 20 18 16 14 12 10 8 6 5 2 D 14 16 18 20 lt 0 4 0 3 0 2 0 1 0 0 1 0 2 0 3 0 4 gt HEADROOM dB CAL LEVEL B 13220 1 A D converter ADC SOURCE INPUT SENS PEAK RESET MODE C Co e mo H G F E grace design m201 owner s manual 9 10 A FS SELECT this switch is used to toggle through the available ADC sampling rates B CLOCK SOURCE this switch is used to select the ADC clock source C ADC MODE this switch is used to select single or dual wire AES and switch between either professional or consumer fomat D OVER lights illuminate when the ADC has been overload ed and remain lit until the PEAK RESET swich is pushed E PEAK RESET MODE This switch is used to clear peaks on the 20 seg ment led meter and to select how the meters display peak information F INPUT SENSITIVITY CALIBRATION SCALE INPUT SENS selects between the two program mable ADC input sensitivity settings H ADC SOURCE selects the input source which feeds the ADC module 1 ADC headroom indicator J 20 segment LED level meter Operating The A D Converter Module If you have purchased the optional A D analog to digital conve
16. es a transient signal EQUIPMENT NEEDED DC Volt meter with at least 1mV sensitivity Plastic alignment tool or a small screwdriver 2 phillips head screwdriver PROCEDURE 1 Remove the 8 phillips head screws from the top lid but leave the lid in place 2 Set all of the preamplifier gain controls to maximum 3 Turn on the m201 preamplifier and allow to warm up for at least 45 minutes go get a nice cup of coffee and do some stretches 4 Remove the top lid and locate the DC offset test points TP1A and TP24A see figure 4 next page Place the Volt meter probes into these holes 5 Locate DC offset potentiometer VR1A VR1B for channel 2 and rotate it for a read ing of 0 000VDC 0 003V 6 The input offset does drift with temperature and having the lid off will allow the circuitry to cool It is advisable to replace the lid and let the preamplifier warm up again about 20 minutes and then re check your adjustments Cleaning Your m201 preamplifier chassis is constructed out of high quality stainless steel Under normal circumstances virtually no maintenance is required to keep the unit looking shiny and new However if your unit becomes smudged or dirty here are some clean ing tips We recommend using either Pledge furniture polish or Zep brand stainless steel cleaner available at the hardware store Apply cleaner to a clean dry lint free cloth and gently wipe all stainless surfaces taking care not to allow the clea
17. inputs are not active while the dual balanced XLR outputs carry the amplified signal from the DI inputs There is no 48V phantom available on this input The phase reverse switch is active and the gain range of this input is 2dB to 44dB 20dB less than the 48V input so therefor the 20dB pad is not available This connector is balanced with the Tip positive Ring negative and Sleeve ground grace design m201 7 owner s manual 8 ribbon This setting puts the m201 into ribbon mic mode which is described in detail below Use this input for ribbon microphones or any application where an additional 10dB of gain may be required In this position the main XLR mic inputs are feeding the preamplifier and the dual XLR outputs are active 130V This setting activates the optional 130V input module for DPA microphones If the 130V input option is present this selection will deactivate the standard XLR inputs and enable the dedicated 4 pin 130V XLR inputs In this mode the 48V pushbutton switch will turn on the 130V power supply Phase reverse and 20dB pad are available in this mode The dual balanced XLR outputs carry the output signal SETTING THE GAIN First turn the gain control fully counter clockwise and check that the 48V phantom power is off Connect a microphone and then turn on the phantom power if required When sending a signal to a recorder converter or interface that has fixed input levels simply increase the gain until the op
18. m the internal crystal an external word clock source or from DigidesignTM loopsync The top middle switch labeled CLOCK SOURCE is used to select between these options The selected clock source will be il luminated green below the switch A D MODE The m201 A D is capable of transmitting AES EBU digital audio in sin gle or dual wire modes and in either professional or consumer format The upper left switch selects between these various formats The selected format will be illuminated green below the switch PEAK RESET MODE High resolution 20 segment metering is included with the m201 A D option When A D input signals hit or exceed absolute zero OdBfs the over indicator lights over placed above and below 0 on the meter will illuminate red remain lit until the peak reset switch is pushed Peak signal levels are indicated by the highest level LED remaining lit The peak in dicators can programmed to remain lit indefinitely until the reset switch is pressed infinite stay lit for 4 seconds delay or not stay lit at all off These three modes are selected by simply pressing and holding the PEAK RESET MODE switch for approxi mately 3 seconds which toggles through the three available modes A D Converter Sensitivity The m201 A D converter features two independent A D sensitivity configurations The front panel interface allows the user to easily switch between these two calibrated set tings Each of the two input se
19. ning prod uct to build up around the panel switches or knobs grace design m201 owner s manual 15 e m NH UL ww 22 nn mm uH m m e n noo m wm mmm o o mm 00000 bbo TIT 224 m 1M 76 2 9 manam am 000 Pie mmmm oo mmm zc 111 eal i gH mH m minit gu giliiiil ma mmn 9 art nooooo 00000 o m TT mm 2 arca um Sim nnn fm 000 oe o o 9 E opo S Oan A d z gt m u dd lt m ree Ogg Te meas Ec OA A OA LL CN C ON LIL LII iH E 555 LOU lt figure 4 offset test point and peak LED adjust trim pots gt FRONT PANEL grace design m201 owner s manual 16 Specifications preamplifier specifications without A D converter Frequ
20. nsitivity ranges A and B can be configured for one of four standard A D sensitivities The following sections detail the operation and calibra tion of this feature SELECTING THE A D SENSITIVITY From the m201 front panel interface pressing and releasing the INPUT SENS push button toggles the selected A D input sensitivity The currently selected range A or B is illuminated CALIBRATING THE A D SENSITIVITY The m201 ships with the following two de fault sensitivity calibrations A 22dBu OdBFS 18dB Headroom B 18dBu OdBFS 14dB Headroom Internal trim controls allow you to reconfigure either or both of the sensitivity levels Four standard sensitivities are supported in the m201 A D converter 18dBu OdBFS 14dB Headroom 20dBu OdBFS 16dB Headroom 22dBu OdBFS 18dB Headroom 24dBu OdBFS 20dB Headroom grace design m201 owner s manual 11 12 The front panel interface features a calibration mode that allows precise adjustment of the A D sensitivity To recalibrate one or both of the input sensitivity configurations simply do the following 1 Disconnect AC power from the m201 2 Remove the 8 top cover screws using a 2 Phillips screwdriver Lift the top cover off the unit and set it aside 3 Reconnect AC power to the m201 and turn it on 4 Connect a signal generator to the A D LINE inputs Set the signal generator output to 4dBu 1kHz 1 29V rms 5 Turn on the m201 A D converter and select
21. ol This knob controls the ratio between the Mid and Side signals in an M S recording setup Please see the pre amplifier operation section of this manual for complete information regarding this feature standby switch Connects the mains voltage and turns on the m201 When depressed the pushbutton will illuminate green and the preamplifier will be on When released the pre amplifier will be in standby mode Rear Panel Connections SRA WORS ca Je meo1 microphone preamplifier El IN ens our AES3 OUT N LEAD FREE me Our COMPLIENT GRACE DESIGN USA XLR mic input connectors Input connections are made via female XLR connectors with pin 2 positive pin 3 negative and pin 1 ground 48V phantom power is supplied on pins 2 and 3 XLR output connectors Parallel XLR outputs are provided for sending line sig nals to two seperate recording devices or mixers Out put connections are made via male XLR connectors with pin 2 positive pin 3 negative and pin 1 ground M S XLR output connectors XLR outputs are provided for sending M S signals in dependently of the standard line outputs Output con nections are made via male XLR connectors with pin 2 positive pin 3 negative and pin 1 ground IEC AC power input Accomodates the included 3 prong AC cable Connect to grounded outlet only 130V DPA microphone inputs op tional
22. rter module for your m201 the following section will help you become familiar with its features and its operation The m201 A D card is available installed on new m201 s from the fac tory or as an upgrade to your existing m201 If you need more information about up grading your m201 with the A D module please feel free to call us at 303 443 7454 INPUT SOURCE SELECT The m201 A D can receive signals from 3 different in puts channels 1 amp 2 from the mic preamplifier section the M S matrix outputs or the external balanced line inputs located on the back panel of the A D module The A D source select switch lower left is used to toggle between the three input source op tions which are illuminated green directly above in the bezel Simply push the button to select the input source you require FS SELECT The m201 A D converter can operate at sampling rates of 44 1 48 88 2 96 176 4 and192kHz Whether operating on the internal crystal or an external clock source you must select the appropriate sampling rate you wish to record at The top left switch above the A D bezel labeled FS SELECT is used to toggle between grace design m201 owner s manual all the available sampling rates Simply push the button to select the sampling rate you require The selected rate will be illuminated green below Selecting OFF puts the A D converter circuitry in low power standby mode with all oscillators off CLOCK SOURCE The m201 A D can be run fro
23. sed and the input mode switch becomes inadvertently changed to 48V 48V phantom will conse quently be activated which can potentially harm a ribbon your microphone if it is still connected to the input If the 48V phantom power switch is turned of and then the ribbon mode is selected the preamplifier will wait until the phantom power voltage grace design m201 owner s manual has completely discharged and then the ribbon mode will activate automatically An additional benefit of the ribbon mic mode is that the input DC blocking capacitors are relay bypassed to further simplify the m201 s signal path Incidentally the ribbon mode works very well with many lower output dynamic microphones as well as ribbon types M S recording with the m201 In M S mode the m201 accepts the Mid signal in channel 1 and the Side signal in chan nel 2 The LEFT channel output connector provides the sum of the inputs and the RIGHT channel output connector provides the difference of the inputs In M S mode the M S width control adjust the ratio of Mid signal to Side signal in the dedicated M S outputs The LEFT and RIGHT M S outputs are always active which allows the user to record the discreet Mid and Side signals from the preamplifier Channel 1 and 2 out puts while also recording or monitoring the stereo composite from the M S LEFT and RIGHT outputs Note For more information on M S recording we would highly recommend the AES paper written by W
24. sign m201 owner s manual Important Safety Information GENERAL Indoor use only Ordinary Protection This equipment should not be exposed to dripping or splasing Avoid placing objects filled with liquids such as vases or glasses on this equipment Class Equipment grounded type Electrical rating 100 120 220 230 240V 50 60Hz 30W Mains supply voltage fluctuations are not to exceed 10 of the nominal supply voltage Pollution Degree 2 Installation Overvoltage Category for transient overvoltages Maximum Relative Humidity 8096 Operation temperature range 10 C to 40 C Storage and transportation temperature range 40 to 70 C Maximum altitude 3000m 9843 ft Equipment suitable for continuous operation Weight preamplifier 7 5kg 16 5165 SAFETY MARKING SYMBOLS CAUTION READ ACCOMPANYING DOCUMENTS This symbol located on the equipment and in this manual refers to impor tant instructions Read this manual thoroughly before operating this equip ment WARNING ELECTRICAL SHOCK HAZARD This symbol located on the equipment and in this manual indicates the potential for electrical shock hazard SERVICE INFORMATION The Grace Design m201 contains no user serviceable components Contact Grace Design for repair and upgrade information In the event that your Grace Design m201 needs to be returned to the factory contact us for a return authorization number grace design m201 owner s manual 3
25. time These procedures should be made only by a qualified service technician or at the Grace Design factory PEAK LED ADJUSTMENT PROCEDURE The peak LED threshold levels may be adjusted to a user defined operating level This circuit is set at the factory with the green threshold at 14dBu and the red threshold at 16dBu The relationship between the two thresholds is fixed The procedure for adjusting the greed red threshold follows EQUIPMENT NEEDED Sine wave audio signal generator or oscillator output from a mixing console Audio level meter or an RMS Volt meter with dBu or dBm scales Plastic alignment tool or small screwdriver Appropriate interconnect cables 2 phillips head screwdriver PROCEDURE 1 With the power off remove the eight phillips head screws from the top cover and remove it from the m201 2 Set all of the gain controls to the 30dB position 3 Connect the audio generator to the input of channel 1 4 Set the generator output level to approximately 20dBu 1KHz 5 If the generator has an unbalanced output refer to figure 2 below for termination information 6 Connect the level meter to the output of channel 1 7 If the level meter has an unbalanced input refer to figure 1 gt for unbalanced output termination information 8 Apply power to the generator preamplifier then the level meter 9 Adjust the generator output level so that the preamplifier output level is at the desired red threshol
26. timum recording level is reached If the peak in dicator flashes red excessively with the gain control in the fully counterclockwise posi tion engage the 20dB attenuator When sending a signal to a tape recorder with an input attenuator i e the record level control on a DAT or CDR recorder use the following procedure With the sound source present turn the gain control clockwise until the peak LED begins flashing red then reduce the gain until the red stops flashing Since red indicates a peak level which is 12dB before preamplifier clipping 6dB in unbalanced mode it is OK for it to come on periodically during recording If peak indicator flashes red excessively with the gain control in the fully counterclockwise position engage the 20dB attenuator Now ad just the recorder input control for the optimum recording level Ribbon Mic Mode Selecting the ribbon mic position on the input mode switch optimizes the channel for ribbon microphones by boosting the gain by 10dB while disabling 48V phantom pow er and optimizing the mic input impedance Before activating ribbon mic mode make sure the channel s gain is fully down counter clockwise and 48V phantom power is off Now simply select ribbon input mode and turn the gain control upwards until the proper recording level is achieved If you press the 48V phantom switch while the ribbon switch is engaged the mic pow er will not turn on However if the 48V phamtom switch remains depres
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