Dual Lowpass Gates + Timbre

Stereo Mixer V1.2 in SMT with balanced outputs:

Stereo Mixer in SMT with balanced Outputs

Dual Lowpass Gate / Timbre / Stereo Mixer ("DONKS")

Classic lowpass gates based on the Buchla 292C plus the amazing timbre wavefolder module of the Buchla Music Easel adapted to 12V and Serge signal levels.

Stereo-Mixer is an equal-power design using high-end THAT2180 VCA chips designed to emulate the behavior of the famous Serge VCAs. Version 1.1 contains a number of additions and improvements that required to have the main pcb produced in surface mounted technology (SMT):

  1. Balanced Outputs, using „a new generation of monolithic audio differential line drivers offering improved performance over conventional crosscoupled designs“ for low noise and distortion. These outputs can be connected to balanced or unbalanced equipment (amplifiers, A/D converters...)
  2. Burr-Brown quad op-amps (OPA4134) in the audio path.
  3. Optimized value set and easier calibration / setup.
The R*S Stereo-Mixer has two independent channels for stereo panning and provides level control (or enveloping) as well as voltage controlled panning. Two Aux inputs allow to mix in other signals (not affected by control voltages or knobs) and to chain mixers. The output is available at a pair of banana jacks as well as (6.35mm / 1/4") TRS jacks (phone connectors) for connecting to external amplifiers, ADCs etc.

The first "Donks" demo uses only the Stereo-Mixer (mostly as a waveshaping tool) - no LPG or timbre was involved:

The Random*Source "Donks" Kit contains:

  • front panel, 2mm, cnc made and anodized in germany
  • 1 Dual LPG + Timbre pcb (2" wide, through-hole, no parts included!) made by Random*Source
  • Component pcb for Dual LPG + Timbre pcb
  • 1 R*S Stereo Mixer 1.3 pcb set (2" wide) with all SMT components (including balanced line drivers, Burr-Brown op-amps) reflow soldered in - only very few through-hole components (THAT2180s, audio capacitors, trimmers ...) have to be added.
  • New version 1.3 - NJR MUSES edition!

Please note that only the Stereo-Mixer pcb is SMT, the LPG pcb is through-hole.

Price: € 250 - BACK IN STOCK! -

RandomSource PCB set



This module combines some of essential Ian Fritz modules: a versatile chaotic signal generator, a sinusoidal quadrature oscillator and the well known TGTSH, a dual Threshold / Gate / Trigger / Sample / Hold Circuit. The TGTSH provides two important synthesizer functions: it produces trigger and gate signals whenever a "timing" signal input crosses a user-defined threshold. At the same time, the trigger pulse fires a high-performance sample-and-hold circuit that samples a second "main" signal input. The Chaos Generator is an analog electronic simulation of the classical driven double potential-well problem, with the addition of extra gain in the circuit loop, and an extra cross-coupling path to extend the range of chaotic patterns available. The double-well system is a second-order system and therefore requires an external driving signal. This is provided by quadrature oscillator. Chaos Generator and Quad Oscillator can be used together or separately.

Ian Fritz CHAQUO + TGTSH module
BOM / Building docs (PDF): Fritz CHAQUO Fritz TGTSH

The Random*Source Kit contains:

  • front panel, 2mm, cnc made and anodized in germany
  • CHAQUO & Dual TGTSH main pcbs (each 6" x 2"), ENIG plated, made in EU
  • 1 component pcb (4" wide) for the entire module, ENIG plated, made in EU

Price: € 140  

Thomas Henry Dual 555 VCO

Thomas Henry Dual 555 VCO and Audio Mixer

Thomas Henry's 555 VCO is probably one of the most precise analog VCOs ever, featuring ramp, triangle, pulse and sine outputs, sync, linear and exponantial FM, pulse wave modulation etc. Might be the best tracking VCO around.

Here's what Thomas Henry said about his design: "My favorite VCO of all times is the CEM3340, and I've always wanted to approximate it somehow. After nearly thirty years, I finally have a design which comes the closest. "

Dual 555 VCO + Audio Mixer

The Random*Source Kit contains:

  • front panel, 2mm, cnc made and anodized in germany
  • 2 VCO pcbs made by Random*Source, now with a footprint to support an SSM2220 matched transistor array
  • 1 component pcb (3") for the Dual 555 by Random*Source
  • 1 audio mixer pcb (1") by Random*Source
  • 1 component pcb (1") for the Audio Mixer


Craig Lee Quantizer

CLEE 8-channel Quantizer

Need some Dim, Blues or Java in your modular life? The CLEE Quantizer features 8 independent channels of quantizing which share common SCALE. BANK and HOLD/SAMPLE AND HOLD controls.

Hold/S&H has 2 modes which are switch selected. In hold mode VC will cause the quantizer to hold its outputs regardless of what is at its inputs. In S&H mode a voltage greater than the treshold will cause the Quantizer to sample its inputs, which will then be held until the next time the threshold is passed.

More info on Craig Lee's Quantizer page.

Please note: Random*Source currently offers the front panel (4U) only - for a version 2 of the CLEE pcb - you need to get the pcb separately from Craig via his website. There's no component pcb (yet)..

  • 4U front panel, 2mm, cnc made and anodized in germany
  • no pcbs!


More Modules on the Serge 4U Module page.

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