Mix 04

_mix-04Mix 04 is an extensible 4 in / 4 out VCA matrix with a total of 16 VCAs. The matrix can route any input to any output. Several Mix 04 modules can be combined to make a bigger matrix.

Analogue Bus
Mix 04 features the new Rebel Technology analogue bus, allowing compatible modules to be interconnected without additional patching. Connect two or more Mix modules to create a mixer with more inputs and outputs. Balanced inputs and outputs can also be added, either for front panel mounting or built in to the modular case.

Price £220 – Coming May 2017

The module features a 4×4 matrix of CV inputs, one for each input (vertically arranged) going to each output (horizontal). The level for the first input going into the first output is set by the CV input jack at the top left of the module. From top to bottom are the CVs for input 1 to 4, and from left to right for output 1 to 4.
The two rows of LEDs indicate the input and output levels respectively. The first row of jacks below the LEDs are the inputs, the row below are the outputs.

On the back of the module there are four 5-pin interconnect headers. Two 5-pin headers connect the input channels and normalled inputs. Normalling means that a connection can be made between two modules when nothing is inserted into the normalled jack. Inserting a plug into the jack breaks the normalled connection.
Two more 5-pin headers connect the outputs.
Connecting the input bus of two Mix 04 modules creates a 4 in / 8 out matrix. Connecting the output bus of two modules creates an 8 in / 4 out matrix. Both connections can be made at the same time, and bigger matrices can be created by connecting more Mix 04 modules.
Thanks to the normalling jacks, the modules can still be used independently while connected to the same input and output bus.

The inputs and outputs are DC coupled, suitable for both audio and control voltage mixing and routing.

The VCA response curve is exponential, with a maximum amplification level and unity gain level which can be tuned over a wide range with two precision trim pots on the back of the module.
The module comes factory calibrated with unity gain at 5V CV level, and maximum 6dB gain.


  • Width: 10HP / 50.50mm
  • Height: 3U / 128.50mm
  • Depth: 35mm
  • Weight: 120g


  • 10-pin Doepfer/Eurorack
  • Reverse voltage protected
  • +12v: < 110mA
  • -12v: < 110mA


  • Outputs: <= 1k Ohm
  • Inputs: >= 100k Ohm

Open Hardware Logo
Mix 04 is Open Hardware, published under the Gnu GPL.

The schematics and BOM are publicly available on GitHub.
Please send your patches to us as pull requests and bug reports as issues on GitHub.

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