Grace m201mk2 User manual

Owner’s Manual Rev A
All contents © Grace Design/ Lunatec LLC
303.823.8100 • www.gracedesign.com
2 Channel Microphone Preampler
m201mk2

grace design m201mk2
owner’s manual
2
Welcome
Thank you for purchasing the Grace Design m201mk2 microphone preamplier. With incredible son-
ic performance and reliability, the m201mk2 is the ultimate, state of the art microphone preamplier
for any recording application.
We have designed the m201mk2 to be as easy and intuitive to use as possible. However, we strongly
recommend that you read this manual thoroughly to familiarize yourself with the unique features
and capabilities of the m201mk2.
Also, please do not hesitate to contact us directly if you have any questions, comments, or concerns
with your new m201mk2 microphone preamplier. Thanks for reading and happy recording!!
-The Grace Design Team
Contents
Welcome 2
Important Safety Information 3
GENERAL 3
SAFETY MARKING SYMBOLS 3
CALIFORNIA PROPOSITION 65 WARNING 3
SERVICE INFORMATION 3
Front Panel Controls 4
Rearpanel Connections 5
Installation 5
POWER CONNECTION 5
TURNING THE POWER ON 5
FUSES 6
MOUNTING 6
AUDIO CONNECTIONS 6
Preamplier Operation 6
SETTING THE GAIN 6
RIBBON MIC MODE 7
Maintenance 7
PEAK LED ADJUSTMENT 7
INPUT OFFSET ADJUSTMENT 8
Specications 10
Dimensions 11
Cleaning 12
Warranty Information 12
Manual Revisions 13

grace design m201mk2
owner’s manual 3
Important Safety Information
GENERAL
• Indoor Use Only
• Ordinary Protection: This equipment should not be exposed to dripping or splashing.
• Avoid placing objects lled with liquids, such as vases or glasses, on this equipment.
• Class I Equipment (grounded type)
• Electrical rating: 100-240VAC 50-60Hz 10 Watts
• Mains supply voltage uctuations 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: 4.6lbs (2.1kg)
SAFETY MARKING SYMBOLS
CAUTION: READ ACCOMPANYING DOCUMENTS
This symbol, located on the equipment and in this manual, refers to
important instructions. Read this manual thoroughly before operating
this equipment.
WARNING: ELECTRICAL SHOCK HAZARD
This symbol, located on the equipment and in this manual, indicates
the potential for electrical shock hazard.
CALIFORNIA PROPOSITION 65 WARNING
This product may contain metallic nickel, a chemical known to the State of California to cause cancer
and birth defects or other reproductive harm. Wash hands after handling.
SERVICE INFORMATION
The Grace Design m201mk2 contains no user serviceable components. Contact Grace Design for re-
pair and upgrade information. In the event that your Grace Design m201mk2 needs to be returned
to the factory, contact us for a return authorization number.

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owner’s manual
4
Front Panel Controls
+48V RBN -20
20
20
30 30
40
40
50
50
60
60
m201mk2
+48V RBN -20
+48V RBN -20
20 20
30 30
40 40
50 50
60 60
m201mk2
+48V RBN -20
DEF
A
CG
B
A
24 POSITION GOLD CONTACT GAIN SWITCH
Each gain control has 24 positions and adjusts
the voltage gain from 18dB to 64dB in 2dB steps.
B
BI-COLOR LED PEAK INDICATOR
The LED peak indicator, which monitors the
output signal, turns green at -16dBu and switches
to red at +16dBu (12dB before clipping). The
threshold level for peak indication is adjustable
on each channel (see page 8).
C
48V PHANTOM POWER SWITCH
The phantom power switch (labeled +48V)
connects the +48V power supply to pins 2
and 3 on the XLR input connector. This switch
illuminates red. A soft start circuit creates a +48V
ramp up time of 1s to minimize microphone turn
on transients.
D
PHASE REVERSAL SWITCH
The phase reverse switch reverses the absolute
polarity of the music signal at the input of the
preamplier. The switch illuminates green and
provides power for a sealed gold contact relay
located on the preamplier circuit board. This
eliminates signal wiring to the front panel and
switch contact performance problems.
E
-20 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
preamplier circuit board. With the -20 switch
engaged, the eective gain range becomes -2dB
to 44dB.
F
RIBBON MIC MODE SWITCH
This switch activates a 10dB increase in overall
preamplier gain while simultaneously disabling
the 48V phantom power circuit to protect
ribbon microphones. As well, the input coupling
capacitors are bypassed and input impedance is
increased to 20k Ohms.
G
STANDBY SWITCH
Turns power to the m201mk2 audio circuitry on
and o. Will illuminate green when the power is
on.

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owner’s manual 5
Rearpanel Connections
microphone
preamplifier
m201mk2
GRACE DESIGN
LYONS, CO USA
21
MIC
OUT OUT
MIC
OUT OUT
m201 mk2
SERIAL
#
MICROPHONE PREAMPLIFIER
250V~ T 200 L
FUSE
100-240V~ 50-60Hz 5W
GRACE DESIGN / LUNATEC LLC
L
YONS, CO 80540
<xxxxxxx>
AB
microphone
preamplifier
m201mk2
GRACE DESIGN
LYONS, CO USA
21
MIC
OUT OUT
MIC
OUT OUT
m201 mk2
SERIAL #
MICROPHONE PREAMPLIFIER
250V~ T 200 L
FUSE
100-240V~ 50-60Hz 5W
GRACE DESIGN / LUNATEC LLC
LYONS, CO 80540
<xxxxxxx>
C
A
IEC POWER INPUT, FUSE HOLDER AND POWER SWITCH
A 6’ AC power cord is supplied to connect mains
voltage (100-240 VAC) to the preamplier unit.
The power switch connects / disconnects the
mains voltage to the preamplier. Fuses are two
T250mA 250V~ 5mm x 20mm Time Delay Fuses.
B
XLR OUTPUT CONNECTORS (PARALLEL)
Output connections are made via male XLR con-
nectors with pin 2 positive, pin 3 negative and
pin 1 ground. An additional set of parallel XLR
outputs are provided for sending line signals to
additional recording devices or mixers.
C
XLR MIC INPUT CONNECTOR
Input connections are made via female XLR con-
nectors with pin 2 positive, pin 3 negative and
pin 1 ground. 48V phantom power is supplied
on pins 2 and 3.
Installation
POWER CONNECTION
The m201mk2 has a built-in universal power supply which accepts line voltages of 100
to 240VAC. We include power cable specied for the country where it was ordered, so
it should be supplied correctly. If not, please contact your dealer or distributor for help.
For safety, it is recommended that the AC power cable be connected to a grounded
outlet. The Disconnect Device for the m201mk2 is the rocker switch on the AC power
entry module. The Disconnect Device must remain accessible and operable.
TURNING THE POWER ON
The power switch is located on the rearpanel in the IEC 320-C14 power entry module. Switching the
rocker switch to the Iposition turns the mains power on. Switching the rocker switch to the Oposi-
tion turns the mains power o. The front panel standby switch turns power to the m201mk2 audio
circuitry on and o and will illuminate green when the power is on.

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6
FUSES
The m201mk2 uses two T250mA 250V~ 5mm x 20mm Time Delay Fuses.
MOUNTING
The m201mk2 can be rack mounted in a standard 19” equipment rack and does not require any extra
ventilation. 4 Rack screws are included in the box.
AUDIO CONNECTIONS
Microphone input connections are made via female XLR connectors with pin 2 positive, pin 3 nega-
tive and pin 1 ground. Note: This will provide a signal of positive absolute polarity when the preamplier
is being used with a microphone which produces a positive voltage on pin 2 with positive air pressure 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. 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 unbal-
anced operation. See the following gure 1.
1
2
3
SHIELD
HOT
GND
(OPEN)
XLR MALE
gure 1 - Unbalanced output cable termination
Preamplifier Operation
SETTING THE GAIN
First, turn the gain control fully counter-clockwise and check that the +48V phantom power is o.
Connect a microphone and then turn on the phantom power if required. When sending a signal to a
recorder, converter or interface that has xed input levels, simply increase the gain until the optimum
recording level is reached. If the peak indicator ashes red excessively with the gain control in the
fully counterclockwise position, engage the -20dB attenuator.
When sending a signal to any recording device with an input attenuator, use the following procedure:
With the sound source present, turn the gain control clockwise until the peak LED begins ashing
red, then reduce the gain until the red stops ashing. Since red indicates a peak level which is 12dB

grace design m201mk2
owner’s manual 7
before preamplier clipping, it is OK for it to come on periodically during recording. If peak indicator
ashes red excessively with the gain control in the fully counterclockwise position, engage the -20dB
attenuator. Now adjust the recorder input control for the optimum recording level.
RIBBON MIC MODE
Pressing the ribbon switch optimizes the m201mk2 channel for ribbon microphones by boosting
the gain by 10dB while disabling 48V phantom power and increasing the input impedance. Before
activating ribbon mic mode, make sure the channel’s gain is fully down (counter-clockwise) and 48V
phantom power is o. Now simply press the ribbon switch 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, nothing will happen. If the
48V phantom power switch is turned o and then the ribbon switch is turned on the preamplier
will wait until the phantom power voltage has completely discharged and then the ribbon mode will
activate automatically. An additional benet of the ribbon mic mode is that the input DC blocking
capacitors are relay bypassed to further simplify the m201mk2’s signal path. Incidentally, the ribbon
mode works very well with lower output dynamic microphones as well.
It is not recommended to use Ribbon Mode and the -20dB pad at the same time. This will cause the
microphone to see a variable input impedance and will cause a low frequency response bump of up
to 10dB depending on the microphone output impedance.
Maintenance
The model m201mk2 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 qualied service technician or the Grace
Design factory.
PEAK LED ADJUSTMENT
The peak LED threshold levels may be adjusted to a user dened operating level. This circuit is set
at the factory with the green threshold at -16dBu and the red threshold at +16dBu. The relationship
between the two thresholds is xed. 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, RMS volt meter with dBu or dBm scale, or digital volt meter (DVM) with AC
RMS measurement.
• Plastic alignment tool or small screwdriver
• Appropriate interconnect cables
• #2 phillips head screwdriver
PROCEDURE

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8
1. With the power o, remove the 14 phillips head screws from the top cover and remove it.
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 (0.077vrms) @1KHz. If the generator
has an unbalanced output, refer to gure 2below for termination information.
12
3
SHIELD
HOT
XLR FEMALE
gure 2 - Unbalanced Output
5. Connect the level meter or DVM to the output of channel 1.
6. If the level meter has an unbalanced input, refer to gure 3 (p. 9) for unbalanced output termi-
nation information.
7. Apply power to the generator, preamplier, then the level meter.
8. Adjust the generator output level so that the preamplier output level is at +16dBu
(4.88VRMS) or another desired red threshold level. If the proper level can’t be reached, adjust
the preamplier gain control.
9. Locate VR2 (see gure 3, p.9) on the channel 1 audio circuit board and adjust until the peak
LED is between green and red. Repeat this procedure for channels 2 through 8.
10. If it is desired to calibrate the peak indicator to a specic AD converter input level, simply con-
nect the output of the preamplier to the converter. Adjust the signal generator so that the
desired peak level is indicated on the converter and then adjust VR2 until the peak LED is be-
tween green and red.
INPUT OFFSET ADJUSTMENT
The input ampliers in the m201mk2 are ultra-precision laser trimmed devices which have a very
low input oset. However, even the smallest dierential oset 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
oset is present. This procedure nulls the input oset and minimizes the clicking sound with no sig-
nal 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 instanta-
neous 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

grace design m201mk2
owner’s manual 9
1. Remove the 14 phillips head screws from the top lid but leave the lid in place.
2. Turn on the preamplier and allow to warm up for at least 45 minutes. (go get a nice cup of
coee and do some stretches)
3. Set all of the preamplier gain controls to minimum (fully counter clockwise).
4. Set all +48V, polarity reverse, pad, and ribbon mode switches to OFF
5. Remove the top lid and locate the DC oset test points TP7 and TP8 (gure 3) on the channel
to be adjusted. Place the Volt meter probes into these holes and note the DC Volts. It should
be in the range of +/- 0.02V.
6. Rotate the gain control to maximum (fully clockwise) and note the DC Volts.
7. Locate DC oset potentiometer VR1 and rotate it for a reading that matches the minimum
gain reading. +/- 0.005V.
8. The objective is to get the minimum gain oset and the maximum gain oset to match as
closely as possible.
9. The input oset does drift with temperature and having the lid o will allow the circuitry to
cool. It is advisable to replace the lid and let the preamplier warm up again (about 20 min-
utes) and then re-check your adjustments.
R2
R6
D7
R29
R31
D15
R5
R19 C16
D9
D16
+48V
C7
C5
R8
D4
C15
C18
R24
CAL
U6
U7
R34
R36
R37
C37
R39
R58
TP1
R1
TP2
GND
1
R3
TP3
D1
TP5
D2
C6
C8
J2
Q1
U4
D5
D3
R21
D8
C17
D10
R23
R25
R27
U8
R32
K1
D11
C29
C35
R38
C36
R45
TP9
D13
Q2
C41
R48
R49
R50
K4
R51
R52
D18
R54
C46
R55
R56
R57
L1
R59
C44 J4
C47
J1
C1
-18 -15
U2
C9
U1
R7 R9
TP8
R18
D6
TP7
C22
R22
C25
R30
R28
R35
C38
R44
C39
K3
J3
R53
D19
C45
RED STRIPE ->
U3 C10
R4
R17
C19
R11
R13
R15
VR1
C14
R46
J6
C49 C11
-15V REG
C12
C3
+15V REG
R16
C2
TP6TP4
C13
C21 C24
C23
METER
CAL
R10
VR2
R14
R12
C20
C28
C26
C32
R41
U9
C33
K2
C34
U10
C40
U11
Q3
AUTO+10dB
D12 C42
R43 D17D14
TP10
+5V
C4
+15+18
U5
R20
C48
R26
C30
R33C27
C31
R40
R47
R42 GAIN
C43
J5
OFFSET
+48V
OFFSET
AT211 Rev
VR1
DC OFFSET CAL
TP7-TP8
DC OFFSET
TEST POINTS
J3
+10dB GAIN / AUTO
VR2
PEAK LED CAL
gure 3 - oset test point and peak LED adjust trimpots

grace design m201mk2
owner’s manual
10
Specifications
PREAMPLIFIER SPECIFICATIONS
FREQUENCY RESPONSE
@ 20dB gain ± 3dB 150Ω source 3.2Hz-530kHz
@ 20dB gain ± 0.2dB 150Ω source 14.8Hz-109kHz
@ 40dB gain ± 3dB 150Ω source 3.2Hz-500kHz
@ 40dB gain ± 0.2dB 150Ω source 15.4Hz-103kHz
THD+N
@ 20dB gain +20dBu out, 1kHz <.0008%
@ 40dB gain +20dBu out, 1kHz <.0009%
@ 60dB gain +20dBu out, 1kHz <.0070%
INTERMODULATION DISTORTION / 40dB GAIN +20dBu OUT
SMPTE/DIN 1:1 (50Hz, 7kHz) <.0007%
SMPTE/DIN 4:1 (50Hz, 7kHz) <.009%
NOISE  REFERRED TO INPUT
@60dB gain 50Ω source 22-22kHz -130dB
@60dB gain 50Ω source A weighting -133dB
@60dB gain 150Ω source 22-22kHz -127dB
@60dB gain 150Ω source A weighting -127.5dB
@40dB gain 50Ω source 22-22kHz -127dB
@40dB gain 50Ω source A weighting -130dB
@40dB gain 150Ω source 22-22kHz -125dB
@40dB gain 150Ω source A weighting -128dB
@20dB gain 50Ω source 22-22kHz -117dB
@20dB gain 50Ω source A weighting -120dB
@20dB gain 150Ω source 22-22kHz -117dB
@20dB gain 150Ω source A weighting -119dB
GAIN RANGE
Default Mode 18-64dB, 2dB steps
Ribbon Mode 28-74dB, 2dB steps
PHASE DEVIATION
@40dB gain 40Ω source 75Hz-45kHz <3°
CROSSTALK
Any Channel @40dB gain 1kHz -140dB
Any Channel @40dB gain 10kHz -130dB
CMRR
@60dB gain, 3.5Vcm, 1KHz >85dB
@60dB gain, 3.5Vcm, 10KHz >75dB
PHANTOM POWER
Voltage +48V +/- 1.0V
6.8kΩ resistor match tolerance +/- 0.1%
MAXIMUM OUTPUT LEVEL
1kHz, 100KΩ load +28dBu
PEAK LED
Green Threshold -16dBu Out
Red Threshold +16dBu Out
IMPEDANCE
Input Nominal 8100Ω
Input Ribbon Mode 20KΩ
Input Pad Engaged 1.3KΩ
Output 150Ω
DIMENSIONS
Weight 4.6lbs (2.1kg)
Height 1.7” (43mm)
Width 19” (483mm)
Depth 10.8” (274mm)
POWER SUPPLY SPECIFICATIONS
POWER CONSUMPTION
100-240VAC 50/60Hz 10 Watts max

grace design m201mk2
owner’s manual 11
254mm
10.00in
428mm
16.84in
20mm
.80in
274mm
10.80in
483mm
19.00in
43mm
1.70in
Dimensions

grace design m201mk2
owner’s manual
12
Cleaning
Your m201mk2 amplier chassis is constructed out of high quality aluminum. Under normal cir-
cumstances, virtually no maintenance is required to keep the unit looking shiny and new. How-
ever, if your unit becomes smudged or dirty, here are some cleaning tips: Apply a small amount
of windex cleaner to a clean, dry, lint free cloth and gently wipe all surfaces, taking care not to
allow the cleaning product to build up around the panel switches or knobs.
Warranty Information
The Grace Design EON limited warranty guarantees this product to be free of defective parts and
workmanship for a period of twenty years.
• The Grace Design EON warranty period begins at either a) the date of original purchase -
original customer proof of purchase required, or b) the date the product was originally
shipped from Grace Design - if original customer proof of purchase is not available.
• This warranty 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 modication, 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.
• Customers within the US are responsible for all inbound freight charges to Grace Design’s
facility, while Grace Design will pay for return freight charges via ground service. Customers
outside the US must contact their distributor for warranty / product return details.
• In order for Grace Design to provide ecient 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 [phone] 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 prots 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 specic 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 m201mk2
owner’s manual 13
Manual Revisions
Revision Page Change Date Initials
A all initial release 04/29/20 edg