PM4x4: 4x4 passive matrix mixer PCB/panel set (14HP)

A re-release of one of my older modules - a 4x4 passive matrix mixer.

For those not in the know, a matrix mixer is a device that routes multiple input signals to multiple output destinations. It allows for flexible and complex routing of signals, enabling users to create custom mixes and effects chains.

Unlike a traditional mixer, which typically combines inputs into a single output, a matrix mixer provides individual control over the routing and mixing of each input to each output.

TL;DR - you can do funky mixing effects with it.

Note that as this is a passive mixer, meaning that you won't be able to generate feedback and other squally effects using the module on its own (you'd need some external amplification for that) but it's still good for taking up to four sources, be it audio or CV, mashing them together and then sending them to up to four different destinations.

(a rejig of my 4x4 active matrix mixer is in the works ...)

Supplied as a PCB/panel set, this is a fairly straightforward build - all the parts are through-hole. Mixer resistor values are a matter of personal choice - I tend to use 10-15k so as to minimise the resulting voltage drop, but don't make them too low or you'll get some bleeding between channels. Pot values are, again, a matter of choice - 50k or 100k linear is a good bet, and the footprint will accomodate Alpha or compatible components.

The boards are black FR4 substrate with gold ENIG plating and white silkscreen printing. The faceplate is 14HP (approx. 70mm) wide.

Finally, eagle-eyed viewers will notice the 'jumpers' JP1-JP4 on the board - these will need to be populated if you want the final build to work; for resistive coupling, a zero-ohm link or wire will do the job, whereas for capacitive coupling (ie. removal of any DC offset) I recommend 100nF film capacitors.

You'll require the following bits:

• Potentiometers: 16x Alpha RK097 or compatible. 100k linear recommended.
• R1-R16: 16x 10-15k, 0.25W - tolerance doesn't matter. 5% is good enough, or you can use 1% if you really want to push the boat out (or have the bits)
• JP1-4: Use zero-ohm link or wire bridge for resistive coupling, 4x 100nF film capacitor for capacitive coupling (this will remove any DC offset from the incoming signal)
• Jacks: 16x PJ301-M/PJ301M-12 (aka ThonkIconn)

Easy, eh?

If you'd like the module pre-built, please contact me in the first instance - a complete module will likely cost around £50, plus shipping.