Grace M201 User Manual

m201

microphone preamplifier

optional A/D converter module

owner’s manual

manual Rev C

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 I 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 II for transient overvoltages.

•Maximum Relative Humidity: <80%

•Operation temperature range: 10 °C to 40 °C

•Storage and transportation temperature range –40 °C to 70 °C

•Maximum altitude: 3000m (9843 ft)

•Equipment suitable for continuous operation

•Weight: preamplifier - 7.5kg (16.5lbs)

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

Front Panel Controls

50m

50s

m201microphone preamplifier

48V

ribbon

48V

ribbon

(

)

(

)

+10dB

HI-Z

130V

30m

70s

INPUT MODE

30s

100m

M+S WIDTH

+48V

- 20dB

HI-Z

+48V

- 20dB

HI-Z

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.

switch

24 position gold contact gain

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 74dB in 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).

-20dB pad switch

The 20dB 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.

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.

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.

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 external 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.

M-S width control

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.

polarity reversal switch

The polarity reverse switch reverses the absolute phase

grace design m201

owner’s manual

Rear Panel Connections

WORD/LOOP CLOCK

PUSH

MIC IN

130V

PUSH

m201^{microphone preamplifier}

S/PDIF

TOSLINK

LINE IN

OUT

AES3 OUT

LEAD FREE

M+S OUT

PUSH

RoHS

COMPLIENT

GRACE DESIGN USA

RIGHT

LEFT

OUT

MIC IN

OUT

MIC IN

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)

Accomodates 130V DPA© microphones via 4 pin XLR

connectors.

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

owner’s manual

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 <ﬁgure 1> 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.

HOT

GND

SHIELD

(open)

<ﬁgure 1> - 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 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 <ﬁgure 2> below. Be sure to use a time

delay fuse with a 250V rating.

CAM SETTING

100V~

120V~

LINE VOLTAGE

100V~

120V~

FUSE VALUE

250V~ T 500mA L

250V~ T 250mA L

250V~T 250mA L

220V~

240V~

220V~

230V~

240V~

<ﬁgure 2 - fuse value table>

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... In this mode, the rear panel XLR

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.

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owner’s manual

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 optimum 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 depressed 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 Wes 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

FS SELECT

CLOCK SOURCE

ADC MODE

44 48 88 96 176 192

OFF

INT WORD LOOP

PRO 2WIRE CONS

sLOCK

OVER

-60 -50 -40 -32 -28 -24 -20 -18 -16 -14 -12 -10 -8 -6 -5 -4 -3 -2 -1

14 16 18 20

HEADROOM dB

-0.4 -0.3 -0.2 -0.1

0.1 0.2 0.3 0.4

OVER

(

)

CAL

LEVEL

CH1-2 MS LINE

/ MODE

(hold)

PEAK RESET

INPUT SENS

ADC SOURCE

grace design m201

owner’s manual

FS SELECT this switch is used to toggle through the available ADC sampling rates

CLOCK SOURCE this switch is used to select the ADC clock source

ADC MODE this switch is used to select single or dual wire AES,

and switch between either professional or consumer fomat

OVER lights illuminate when the ADC has been overload-

ed, and remain lit until the PEAK RESET swich is pushed

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.

INPUT SENSITIVITY CALIBRATION SCALE

INPUT SENS selects between the two program-

mable ADC input sensitivity settings.

ADC SOURCE selects the input source which feeds the ADC module

ADC headroom indicator

20 segment LED level meter

Operating The A/D Converter Module

If you have purchased the optional A/D (analog to digital) converter 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&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 from 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 (0dBfs), the over

indicator lights (‘over’ placed above and below ‘0’ on the meter) will illuminate red and

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 sensitivity 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 = 0dBFS (18dB Headroom) (B)+18dBu =

0dBFS (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 = 0dBFS (14dB Headroom) +20dBu = 0dBFS (16dB Headroom)

+22dBu = 0dBFS (18dB Headroom) +24dBu = 0dBFS (20dB Headroom).

grace design m201

owner’s manual

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 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 “0” 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 0. If the signal level is low, the 0 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. Each of these are labeled on the A/D module circuit board <ﬁgure 3>.

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.

C27

R11

R39

R12

R32

R23

R26

C14

C36

C17 C32

C15

C25

C11

C41

R22

CH2 (B): VR4

CH1 (B): VR1

3362

B VR4

A VR3

VR1 B

VR2 A

R38

3362

CH2 (A): VR3

CH1 (A): VR2

R13

R19

R31

R29

R10

R16

C40

C21 C31

C10

TP1 TP2

+15VA

TP3 TP4 TP5 TP6

+18V

-18V -15VA +6.5V +3.3V

C46

C20

C29

U11

C13

C42

FD1

FRONT PANEL

<ﬁgure 3 - A/D sensitivity trim pot locations>

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owner’s manual

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 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> 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 threshold. 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 creates 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 TP2A (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 cleaning prod-

uct to build up around the panel switches or knobs.

grace design m201

owner’s manual

��

<ﬁgure 4 - offset test point and peak LED adjust trim pots>

grace design m201

owner’s manual

Specifications

preampliﬁer speciﬁcations (without A/D converter)

Frequency Response

@ 40dB gain ± 0.2dB (50Ω source)

@ 40dB gain ± 3dB (50Ω source)

THD+N

18Hz-65kHz

4.5Hz-350kHz

@ 20dB gain +25dBu out, 1kHz

@ 40dB gain +25dBu out, 1kHz

@ 60dB gain +25dBu out, 1kHz

Intermodulation Distortion

@ 40dB gain +25dBu out

SMPTE/DIN 1:1 (50Hz, 7kHz)

SMPTE/DIN 4:1 (50Hz, 7kHz)

Noise - Referred to Input

@ 60dB gain 50Ω source

@ 60dB gain 150Ω source

@ 60dB gain 600Ω source

Phase Deviation

100Hz-20kHz @40dB gain

Crosstalk

Any Channel @ 40dB gain 1kHz

Any Channel @ 40dB gain 10kHz

CMRR

<.0008%

<.0009%

<.0070%

<.0020%

<.0030%

-130dB

-127dB

-123dB

<3°

-125dB

-115dB

@ 60dB gain, 3.5Vcm, 1kHz

@ 60dB gain, 3.5Vcm, 10kHz

Maximum Output Level

1kHz, 100KΩ load

>70dB

+28dBu

Impedance

Input

Input, ribbon mode

Output

8100Ω

20kΩ

190Ω

Peak Led Meter

Green threshold

Red threshold

-14dBu

+16dBu

Weight and Dimensions

dimensions

weight

2U, 19”rack mount x 10” deep

16.5lbs (7.5kg)

Power Consumption

100/120/230/240V~ 50-60Hz

20 Watts Max

A/D module speciﬁcations (line input)

Dynamic range

20Hz-20kHz

“A” weighting

>115dB

>117dB

THD+N

1kHz, -1dBFS, 20Hz-22kHz

Frequency response

< 0.00026% (-112dB)

-3dB

+/-0.2dB

44.1kHz Fs

48kHz Fs

5Hz-21kHz

5Hz-23kHz

5Hz-41kHz

5Hz-45kHz

5Hz-54kHz

5Hz-59kHz

22kHz

24kHz

44kHz

48kHz

72.5kHz

79kHz

88.2kHz Fs

96kHz Fs

176.4kHz Fs

192kHz Fs

Full scale input level

+16dB or +24dB (+/-2dB trim)

CMRR

60Hz

1kHz

>65dB

>80dB

>60dB

10kHz

IMD SMPTE 4:1 60Hz, 7kHz, -3dBFS

Interchannel crosstalk

<100dB (0.0008%)

<120dB

Group delay

44.1-48kHz

Sample rates, internal crystal (kHz)

13/Fs

44.1, 48, 88.2, 96, 176.4, 192

External Clock Lock Range

Wide lock mode

s-Lock™ mode

40.1kHz-207kHz (+/-8% at each sample rate)

+/-250ppm (+350, -400ppm typical)

Intrinsic Jitter, 200Hz-20kHz BW

Jitter Rejection Corner Frequency

A/D sensitivity

Wide lock mode

s-Lock™ mode

< 60ps RMS

< 40ps RMS

Wide lock mode, -3dB, 12dB/octave

s-Lock™ mode, -3dB, 12dB/octave

800Hz

10Hz

Range A

Range B

+22dBu = 0dBFS (18dB headroom*)

+18dBu = 0dBFS (14dB headroom*)

*can be calibrated for any setting between +18dBu = 0dBFS and +24dBu = 0dBFS

grace design m201

owner’s manual

Signal Flow Diagram

grace design m201

owner’s manual

Warranty Information

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.



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.

In order for Grace Design to provide efﬁcient and timely warranty service, it is



important that you mail the completed 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.

This warranty is in lieu of all other warranties whether written, expressed, or

implied, INCLUDING ANY WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A

PARTICULAR PURPOSE.



In 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

owner’s manual

Manual Revisions

Revision Page

Change

Date

Initials

mbg

edg

Initial release

04/25/2007

04/26/2007

11/08/07

Changed voltage range and power speciﬁcations

Power switch description changed to standby switch.

Added power mains disconnect information

Added signal ﬂow diagram

9-12

Added A/D module inﬁrmation

edg

grace design m201

owner’s manual

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