8 HP
30 mm deep
Current Draw
25 mA +12V
15 mA -12V
0 mA 5V
$96 Price in €

Module is available as a DIY project only.

This Module is currently available.

A Modular Eurorack Stereo Mixer


STEREO SUM is a stereo mixer with a customizable amount of stereo channels. You can decide yourself how many SUM CHANNELS you want to build and add to your SUM MAIN module. They are all connected via a flying bus cable and standard ribbon cables on the back. You can start with two channels and extend the mixer according to your needs and HP available.

Each CHANNEL has a mute switch, a one knob EQ, Pan, a Send knob that can be routed to two different destinations, a Level pot and an AFL (after fade listening) functionality, which allows you to audit your sounds on the headphones before you add them to the mix. Fully counter-clockwise the channel is only routed to the headphones (AFL), turning it clockwise it will be smoothly subtracted from the headphone out and added to the main mix (Mix).

The SUM MAIN module has all output, send and return jacks, a master volume knob and a 6.3mm stereo headphone jack with a dedicated volume potentiomter. The Mix to AFL knob routes the main mix output to the headphone out in order to compare the channels that are in AFL mode with the main mix. This can be deactivated with a switch to only audit channels that are currently not send to the main output (AFL mode). Additionally there is a stereo input to integrade other mixers, like PHOEBE, SUM or uSUM for example.

All inputs can also handle mono signals. The send channels can be set to be active either pre or post AFL per channel via a solder bridge. ‚Pre‘ means you can still hear the send/return way when it is in AFL mode (thus the channels signal is actually not audible in the main mix), ‚post‘ means send/return will only work when the channels signal is routed to the main mix. Each channel has two separate GAIN trimmer potentiometers adjustable from the front.

STEREO SUM is a true performance mixer aiming to be used in live situations.

• Stereo Mixer
• Customizable Amount of Stereo Channels
• EQ per Channel
• Two Send/Returns
• AFL Mode to Audit Sounds
• Mute Switch per Channel
• Stereo Input to Integrate other Mixers
• Mix to Headphone Knob for Sound Comparison
• Skiff Friendly
• Wrong Polarity Protection
• 3U Eurorack module, 8 HP + 6 HP + N HP wide
• Power consumption: 65 mA at +12 V and 42 mA at -12 V for SUM MAIN and one SUM CHANNEL

Each module consists of two boards:
• Front PCB Panel
• Main PCB


submitted Jun 4th 2020, 20:40 by Stobbert | last Change May 31st 2022, 12:04 by pugix

2 Users are observing this