Grace Design m103


Grace Design m103

Channel Strip – Mic Preamplifier / EQ / Compressor

The m103 starts with the tried and true m101 microphone preamplifier circuitry. For many engineers, the m101 is an introduction to what quality mic preamplification is all about, and the perfect starting point for a channel strip – musical, transparent, and pure. Headroom, detail, clarity – it’s all there. Complete with Grace Design’s exclusive ribbon mic mode, a 75Hz HPF, and 48V phantom power.

The 3-band EQ section is built around single-stage parallel tuning architecture, which minimizes circuitry and delivers natural tonal shaping from 20Hz to 20kHz. Controls include a fully parametric mid, with sweepable high and low bands which can be operated in shelving or peak modes. Because of the accuracy of this design, smaller increments of cut or boost can be heard, providing a greater level of control over tone shaping.

The compressor circuit is based on an optical attenuator – the purest, high-fidelity gain control mechanism available. It provides gentle limiting to fairly heavy compression while remaining neutral and transparent. The perfect way to zip it all up and send it downstream – clean, intact, and alive.

10 segment gain reduction and output meters make monitoring compression and output levels simple. The front panel accessed HI-Z input makes this an amazingly high-quality instrument preamp. Comprehensive I/O options allow the mic pre and EQ/COMP sections to be accessed independently of each other, and the order of the EQ/COMP is switchable.

A dual function link/sidechain input on the rear panel is provided for inserting external sidechain signals (for de-essing, ducking) or connecting two m103’s together for stereo compression applications. Predictably, the m103 is built to last, and proudly backed by Grace Design’s 5-year transferable warranty. So there it is, Grace Design has done it. The m103 – a channel strip by name, a powerful tool by design.

Check out a track that features m103’s on overheads and electric guitars.


  • Fast and musical transimpedance microphone preamplifier architecture
  • Updated audio path with 0.5% precision metal film resistors
  • New 12 position gold plated rotary gain switch
  • High-performance output line driver amplifier and HPF amplifier
  • 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
  • Newly designed optical compressor
  • Mic amp direct output
  • EQ/COMP section line input
  • Bombproof laser-etched black anodized front panel
  • Sealed gold contact relay for Hi-Z input switching
  • Built-in power supply
  • LED indicators for +48V, Ribbon mode, and HPF
  • Powerful 10 segment meters for gain reduction and output level
  • Five-year transferable warranty on parts and labor
  • Made in the USA

Gain Range (5dB Steps)

  • Mic input: 10-65dB
  • Hi-Z input: -10-45dB

THD+N 1kHz, 22Hz-22kHz BW

  • @ 20dB Gain +20dBu out: <0.00085%
  • @ 40dB Gain +20dBu out: <0.0010%
  • @ 60dB Gain +20dBu out: <0.0050%

Intermodulation Distortion

  • @ 40dB Gain +20dBu out
    • SMPTE/DIN 4:1 7kHz/50Hz: <0.0020

Noise – Referred to Input @60dB Gain 22Hz-22kHz BW

  • 50Ω source: <-130dB
  • 150Ω source: <-128dB
  • 600Ω source: <-124dB

CMRR @60dB Gain, 3.5VCM

  • 100Hz: >60dB
  • 1kHz: >75dB
  • 10kHz: >65dB

Frequency Response

  • Mic input @ 40dBm Gain -3dB: 3.7Hz-140kHz
  • Hi-Z input @ 20dB Gain -3dB: 1.2Hz-112kHz


  • Mic input: 8.1kΩ
  • Mic input, Ribbon mode: 20kΩ
  • Hi-Z input (unbalanced): 2.5MΩ
  • Hi-Z input (unbalanced): 5MΩ
  • Balanced Output: 300Ω
  • Unbalanced Output: 150Ω

Peak LED Meter

  • Green Threshold: -10dBu
  • Red Threshold: +16dBu

Maximum Output Level

  • 100k Ohm load, 0.1% THD: +28dBu

EQ Comp Section

Gain Range

  • Output Trim: -10 – +10dB

EQ: 3 Bands of 0-12dB Cut or Boost

  • Low Frequency Range: 20Hz – 750Hz
  • Mid Frequency Range: 500Hz – 4kHz
  • Mid Frequency Q: 0.5 – 5
  • High Frequency Range: 3kHz – 20kHz
  • Low and High Frequency Peak/Shelf switches

Compressor – Inserts Pre or Post EQ

  • Threshold Range: -15 – +15 dBu
  • Attack Range: 3 – 200 ms
  • Release Range: 0.03 – 3 s
  • Ratio Range: 1:1 – 12:1
  • Gain Reduction: 0 – 10dB

THD+N 1kHz, 22Hz-22kHz BW

  • @ 0dB Gain +20dBu out: <0.002%

Intermodulation Distortion

  • @ 0dB Gain +20dBu out
    • SMPTE/DIN 4:1 7kHz/50Hz: <0.002%

Output Noise 22Hz-22kHz BW

  • @0dB Gain: <-78dB

CMRR @0dB Gain, 3.5VCM

  • 100Hz: >75dB
  • 1kHz: >75dB
  • 10kHz: >75dB

Frequency Response

  • @0dB Gain -3dB: 0.016Hz-150kHz


  • Line in: 24kΩ
  • Main Out balanced: 350Ω
  • Main Out unbalanced: 150Ω
  • Link In – sidechain mode: 100kΩ

Level Meters

  • EQ Peak threshold: 6 dB below interstage clipping
  • Output Level VU Meter: 0dB VU = +4dBu output
  • Gain Reduction Meter: 0-10dB Gain Reduction

Maximum Output Level

  • 100k Ohm load, 0.1% THD: +28dBu

Weight and Dimensions

  • Weight: 4.5 lbs / 2.05 kg
  • Dimensions: H1.7” x W19” x D9.0” / H4.3cm x W48.3cm x D22.9cm

Power Consumption

  • 85-264VAC / 120-370VDC: 14 Watts Max