This afternoon I was thinking of making a mixer for my euro rack module. I’ve build mainly effects modules, and some of those I want to chain or combine in all sorts of combinations, in a flexible way. So when I saw a review of the MTX-8 (by FSS), which is a matrix mixer, I wondered how the electronics would look like. So I made this draft of a simple matrix. It has 4 inputs and 4 summing outputs. By closing a switch in the matrix you can connect an input to one of the summing outputs. The input op-amps are there for buffering purposes and I’m assuming unity gain for all op-amps. Obviously the switch could be some pin like construction like the MTX uses or something completely different. This matrix could of course be N inputs and M outputs (or 8 * 8 like the MTX-8) but for the sake of discussing the design I only wanted to draw a 4 * 4 version here. Any output can be connected with any remaining input so trails of signals and intermediate summations being added together should be possible.
The attenuation could be done by using pins like in the MTX or where there are pins with different attenuation factors (like in the EMS Synthi). It all depends on whether you are targeting a routing matrix or a mixer or something in between.
[Edit] But I like the uni/bipolar aspect of the Ken Stone matrix.
A friend of mine spoke about patch cables with in build pots which he uses to adapt euro rack signal levels to standard amplifier input signal levels. So yes, they seem to exist.
The Syntrx exemplifies one of the strategies I’ve considered for hybrid integration. The issue I have is the combinatorial complexity of a plugboard system. A relatively sparse patchboard is far more efficient at any scale. The one thing the plugboard excels at, and this is no small thing, is making analogue patches easier to digitise. Instead of painstakingly recording the cable geometry by hand you can just automatically record the plugboard matrix settings.
It’s a challenge I’m working on, but my current integration strategy is far less radical.
