CG Products
design — construction — sound

Eurorack Module


Low Noise Preamp for Microphones and Pickups

The Pre module allows the embedding of signals from electro dynamic sound sources such as microphones or pickups (e.g. e-guitars) in modular synthesizer equipment. Its high amplification together with a very low noise floor allows the processing of even very low input signals (such as from dynamic microphones). The module is equipped with a ‚Sensitivity‘ knob to adapt it to different input levels, coming from different pickups or microphones. A red LED indicates when the level is overdriven, causing the signal to become saturated; here the preamp soft clips the signal. Additionally, a trimmer on the back of the module allowes the setting of the max. output gain – between 3Vpp and 18Vpp. Further, there is a jumper to optionally supply an electret microphone with +12V power supply, provided on the middle ring of a 3-pole jack. From Rev.2, there is a 2nd minijack/banana input which may be alternatively used instead of the 1/4′ jack input; it will be switched off when a plug is applied to the main input jack.
Pre Minijack Version front view
  • Very low noise
  • Adjustable input sensitivity
  • Soft clipping behaviour with red indicator LED
  • Output gain trimmer (max. output signal ca 18Vpp)
  • Optional +12V power supply for electret microphones
  • Available with banana or 3,5mm minijacks
  • Eurorack module
  • Width: 5 HP
  • Dimensions: 128,5 mm x 25,2 mm
  • Depth: 40mm
  • Supply voltage: ±12V
  • Current consumption (postive rail, without load): ≈10mA

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Pre documentation title
Pre minijack drawing
Pre side view right I
Side view right I
Pre side view right II
Side view right II
Pre side view left
Side view left
PRE side view banana
Side view banana


Simple patches with other (CG Products‘) modules

Patch Description Audio

1. Pre & XR22VCO FT

The Pre’s output is connected to the XR22VCO’s AM input. The oscillator is amplitude-modulating the microphone signal and vice versa (ring modulation with oscillator tone)

Pre In: Microphone with trumpet XR22 VCO: Different frequency settings


2. Pre & Delay1022

The Pre’s output is connected to the Delay1022 input ‚In1‘. Delay, phasing and flanging effects.

Pre In: E-guitar … Delay1022 T CVin: Sinewave Oscillator


3. 2x Pre & X multiplier

Ringmodulation of 2 acoustic signals (from e.g. 2 different microphones, 1 instrument pickup & 1 microphone etc.).

Pre1 In: Microphone with voice…with harmonica Pre2 In: E-Guitar


4. Pre & PEAK+HOLD

The PEAK+HOLD’s 1/4′ jack input is optimized for higher signal levels coming from pickups mounted on a drum, so a preamp is needed if the P+H module shall be sourced from a microphone.

Pre In: Microphone with voice…with bongos/cymbal PEAK+HOLD CV outs controlling XR22VCO and Delay1022