Ljunggren Audio

Roll Your Own

Eurorack DIY




Download assembly manual here. (1MB)


An easy to build 4-channel amplifying mixer/attenuator with 2.0x gain (6dB) and 5.0V offset on each channel in an 8hp module. No calibration required.


Ampmix was designed as a handy CV mixer and processor with good precision, high input impedance and buffered outputs. It could be upgraded for even better precision as described in the assembly manual.


It will also work great with audio, even with full gain giving some distortion possibilities or gaining external gear.


It works as a 4 channel mixer,

1 attenuator + 3 channel mixer,

2 attenuators + 2 channel mixer

or 4 attenuators.

With up to 2.0x gain (6dB) on each channel.


If you chain channels you can get greater gain. You can chain any combination of channels it doesn't have to be in the described order.

Patch signal to IN1, OUT1 -> IN2 and OUT2 have 4x gain (12dB) total.

Continue with OUT2 -> IN3 and OUT3 have 8x gain (18dB) total.

Continue with OUT3 -> IN4 and OUT4 have 16x gain (24dB) total.


An offset voltage is generated then normaled to the inputs of the 4 channels, giving them a maximum of 5V out each with knobs turned full clockwise (2.0x gain). Please note that these offsets will affect the mixing if the channel hasn't been patched on its input or output, so turning all unused channels fully counter-clockwise/left (off) is advisable for a clean mix.



The Ampmix Kit is a novice-friendly project, it is a low part count, single-PCB build that only requires the most basic experience in PCB soldering and module assembly. Kits comes supplied with PCB, front panel (PCB material), component kit, knobs, power cable and mounting screws. Solder and tools are not supplied.



Download assembly manual here. (1MB)

Download schematics here.


Basic specifications

Width: 8hp

Depth with power cable attached: Less than 35 mm.

Power: +/- 22 mA







Download assembly manual here.


Vertmix is out of production, new version coming but we don't know when.

It will have surface mounted resistors and ceramic capacitors in 0805 size. The rest of the components will be thru hole. Preliminary PCB illustration of version 1.5.



* Regarding our PCB/panel only offerings, please note that these are mainly offered due to popular demand from the experienced DIY community. Hence we are counting on that you know what you are doing and how to source parts. If you feel the least bit uncertain, please consider going for the kit.