Grace Design M103 Users Manual
channel strip
info@gracedesign.com / www.gracedesign.com
owner’s manual Rev A
all contents © Grace Design/ Lunatec LLC
2434 30th Street, Boulder, CO 80301 USA
tel 303.443.7454 fax 303.444.4634
Welcome and thanks for purchasing the Grace Design m103 channel strip. We build all of our products to be completely
reliable and easy to use, so you can concentrate on making great recordings, not struggling with complicated equipment
or dicult product manuals. While you will nd the m103 is completely straightforward to use, we do ask that you spend
a little time familiarizing yourself with this product manual to help avoid any common user diculties.
In the event that you do encounter any technical diculties with this or any of our products, feel free to call us at 303443-7454. Our oce hours are 9 to 5, Monday through Friday, MST, or you may email any technical questions to: info@
gracedesign.com.
Also, please check out our web support page listed below for the latest Grace Design product information, owners
manuals and technical documents.
Grace Design has been building audiophile-quality products for the recording industry for over 15 years. The technology
in the m103 is the result of extensive listening, eld-testing and careful renement. Your new m103 channel strip
represents a combination of absolutely pristine audio performance, robust mechanical construction and bombproof
reliability at a reasonable price. Regardless of what audio sources you plan to record, your m103 will faithfully serve as a
versatile link between your microphone or instrument and recording device.
We sincerely hope our products help you achieve a new level of excellence in your work!
Table of Contents
Important Safety Information 3
Safety Marking Symbols 3
Features 4
Front Panel Controls / Features 4
Rearpanel Connections 6
Installing and Connecting the m103 7
Operating the EQ Section 8
Operating the COMP Section 9
Metering 11
Setting the TRIM control 11
Block Diagram 12
Wiring Diagram 13
Specifications 14
Warranty Information 16
Manual Revisions 17
2
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: 100-240V~ 50-60Hz 14W
• 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: preamplier - 2.05kg (4.5lbs)
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.
SERVICE INFORMATION
The Grace Design m103 contains no user serviceable components. Contact Grace Design for repair and upgrade
information. In the event that your Grace Design m103 needs to be returned to the factory, contact us for a return
authorization number.
3
Features
• Fast and musical transimpedance microphone preamplier architecture
• High delity audio path with 0.5% precision metal lm resistors
• 12 position gold plated rotary gain switch
• High performance output line driver ampliers
• Ribbon mic mode (also great for dynamic mics)- Relay bypass of phantom power decoupling capacitors, increased
input impedance, and 48V lockout
• 3-band precision EQ, fully parametric mid band, peak and shelf mode for hi and low bands
• Optical Compressor
• 10 segment Gain Reduction and Output VU meters
• Mic Amp direct output
• EQ/COMP section line input
• Laser-etched black anodized frontpanel
• Sealed gold contact relays for all signal switching
• Built in universal power supply
• Five year transferable warranty on parts and labor
• Made in the USA
Front Panel Controls / Features
18
9
8
linemic
HI-Z
10dB
GAIN
65dB
48V ribbon
EQ
75Hz
100
0
20
750
1212
-
lo gain lo freq hi gain
1.8k
.5k 4k
mid freq
2.5
.5 5
mid Q
0
12 15
12
-
mid gain
10.8k0
3k
1212
-
hi freq
123 4 5 678 9 10 11 12 13 14 15 16 17
peak
20k
10
COMP
0
eq
comp
comp
in
15
eq
threshol d attack release ratio
20 21 22 232425 262728 29
19
3
4
7
5
150
.03
200
3
-
6
1. 1/4 inch TRS instrument HI-Z input - Designed to accommodate a wide variety of high impedance input sources,
making the m103 an excellent choice as a DI instrument input.
2. PEAK INDICATOR - The LED peak indicator, which monitors the signal at the output of the mic preamplier, illuminates
green at -10dBu and red at +16dB (12dB before clipping). Located between the HI-Z input and GAIN controls.
3. GAIN CONTROL - The gain control has 12 positions and adjusts the voltage gain on the microphone input from 10dB
to 65dB in 5dB steps. When using the instrument input, the gain range is –10dB to 45dB in 5dB steps.
4. 48V PHANTOM POWER - This switch provides 48 volts to power condenser microphones. The phantom power switch
(labeled 48V) connects the +48V power supply to pins 2 and 3 on the XLR input connector. LED indicator illuminates
red when active or phantom power on or is present from another source (mixer, interface).
12
- - - - - -
GR
1
secms
5 1
20 7 3 010
1:4
3 1:1 1 2:1
1 2 3
link
in
(SC)
m
VU
103
10dB 10dB
-
TR IM
5. RIBBON SWITCH - This switch activates ribbon mic mode (also great for dynamic mics). This mode activates the
relay bypass of phantom power decoupling capacitors, increases microphone input impedance, and locks out 48V
phantom power to prevent accidental damage to delicate ribbon microphones. LED indicator illuminates white
when active.
6. 75Hz HIGH PASS FILTER - Sometimes referred to as a bass roll-o, the high pass lter rolls o at 75Hz. This 12dB/
4
octave lter employs a transitional Thompson - Butterworth response for the best combination of passband atness
and time domain response. LED indicator illuminates amber when active.
7. MIC / LINE switch - This switch selects which input feeds the EQ/COMP section - either the microphone preamplier
input (MIC IN from the rear panel XLR or the front panel HI-Z TRS input), or the balanced XLR LINE IN on the rear
panel. The LINE IN input is after the mic preamp section and is the direct input to the EQ/COMP section. In either
scenario, the mic preamplier is always active.
8. LOW GAIN (EQ section) - This knob controls the amount of cut or boost applied to the selected low frequency, from
-12dB to +12dB.
9. LOW FREQ - This knob selects the frequency of the low band EQ, from 20 Hz to 750 Hz.
10. LOW frequency EQ type switch - This switch selects the low EQ response mode between shelving and peak .
11. MID GAIN (EQ section) - This knob controls the amount of cut or boost applied to the selected mid frequency, from
-12dB to +12dB.
12. MID FREQ - This knob selects the frequency of the mid band EQ, from .5kHz to 4kHz.
13. MID Q - This knob controls width / sharpness of the mid EQ control, with a range from .5 (the widest, with the most
eect on adjacent frequencies) to 5 (the sharpest, with the least eect on adjacent frequencies).
14. HIGH GAIN This knob controls the amount of cut or boost applied to the selected high frequency, from -12dB to
+12dB.
15. HIGH FREQ - This knob selects the frequency of the high band EQ, from 3kHz to 20kHz.
16. HIGH frequency EQ type switch - This switch selects the high EQ response mode between shelving and peak
17. EQ IN SWITCH - This switch activates the EQ circuit. The LED above the switch illuminates when the EQ is active, turns
o when deactivated. This switch controls a gold contact relay.
18. EQ/COMP Peak LED - displays peaks within 6dB of internal clipping in the line section.
19. EQ>COMP / COMP>EQ - This switch selects the order of the EQ and Compressor circuits.
20. TRESHOLD - This knob sets the minimum level at which the compressor circuit is activated, with a range of +15dB to
-15dB.
21. ATTACK (ms) - This knob sets how quickly (or slowly) the compressor circuit attenuates the incoming signal.
22. RELEASE (sec) - This knob sets how quickly (or slowly) the compressor circuit releases the attenuation of the incoming
signal.
23. RATIO - The ratio control determines the input/output ratio for signals above the threshold level. Higher ratios result
5
in a more aggressive gain reduction while lower ratios will result in more gentle gain reduction.
24. COMP IN SWITCH - This switch activates the COMPRESSOR circuit. The LED above the switch illuminates when the
COMP is active, turns o when deactivated. This switch controls a gold contact relay.
25. LINK (SC) - This switch is to activate either a) linking of two m103’s compressor’s side chain circuits – for use in stereo
compression scenarios, or b) to activate external side chain control of the compressor for ducking, de-essing etc...
26. GR METER - This 10 segment meter displays the amount of gain reduction being applied to a signal in the
compression circuit.
27. VU METER - This 10 segment meter displays the VU (volume units) at the m103’s output. 0VU=+4dBu.
28. TRIM CONTROL - The trim control provides 20dB of variable level control at the output of the m103, from -10dB to
+10dB. This control is useful for small level adjustments during tracking or for compression gain makeup.
29. POWER STANDBY SWITCH - The power switch activates the power supply circuitry. When in the up position, the green
POWER LED will illuminate. When in the down position the m103 is in standby mode. To completely disconnect
power from the m103 remove the AC power cord.
Rearpanel Connections
PUSH
10
8
9
7
6
45
2
1. MICROPHONE INPUT - The XLR microphone input connection, wired with pin 2 positive, pin 3 negative and pin 1
ground. 48V phantom power, when used, is supplied on pins 2 and 3.
2. MIC PRE OUT - The balanced XLR direct output of the mic preamp section, before the EQ/COMP section. The
connector is wired with pin 2 positive, pin 3 negative and pin 1 ground.
3. UNBALANCED MIC PRE OUT -The unbalanced 1/4” direct output of the mic pre section, before the EQ/COMP section.
The connector is wired with tip positive, sleeve ground.
4. LINE INPUT - The balanced XLR input of the EQ/COMP section, after the mic preamp. This connector is wired with pin
2 positive, pin 3 negative and pin 1 ground.
5. MAIN OUT XLR- The balanced XLR output of the entire m103, including the mic preamp (if selected), EQ and COMP
sections. The connector is wired with pin 2 positive, pin 3 negative and pin 1 ground.
PUSH
13
6. MAIN OUT TRS - The balanced TRS output of the entire m103, including the mic preamp (if selected), EQ and COMP
sections. The connector is wired with tip positive, ring negative, and sleeve ground.
7. UNBALANCED MAIN OUT - The unbalanced 1/4” output of the entire m103, including the mic preamp (if selected), EQ
6
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