The idea of a connection matrix arrived when I was playing with patches on the Korg ms-20 mini. I realized that during live sessions, I couldn’t change the current patch. It was quite frustrating and the idea of a connection matrix came to my mind.
After some research, the only existing product I came across was the Erica Synths Matrix Mixer which is a 16x16 matrix. Its form factor and interface weren’t convincing me. To patch two wires together you need to navigate through the matrix with two potentiometers (one for x axis and another for y). This seems so inefficient to me, I wanted to have big buttons to make my patches with an easy user interface.
With all that in mind, I created the lx-mat-001, an 8x8 connection matrix. Each patch can be done and un-done by simply pressing one of the 64 RGB buttons. With two buttons and a selector, it is possible to save and load patches from the memory easily and the intuitive color coding of the RGB button helps you to distinguish between the current patch and the patch you want to load.
To go deeper in what compose the 8x8 matrix, here are the different key components I chose to build it:
One Arduino mega pro (Similar to Arduino mega but with a smaller footprint)
8 Multiplexers, I used 74HC51 breakout board
One 12 segments display by seeed studio
4 4x4 Neotrellis Keypad by Adafruit
The final look of the matrix is inspired by many old-school synthesizers with two nice red side panels of wood.
The front panel is made of black anodized aluminum with a bead-blasted finish. I used PCBway services to make this aluminum panel.
The rest of the case has been 3D printed in PLA and the whole case has been designed in Fusion 360.
You can also spot the eurorack matrix module front panel which is a simple 4x4 matrix using the same technologies.
The current matrix sadly suffers from crosstalk due to the use of separated modules connected together with free wires. Another downside of the current design is the multiplexers which only work either in -5V..5V or 0..10V which won’t suit every modular synth setup.
Besides all those, the matrix works quite well and is an awesome tool to use in live setup!
The project doesn’t stop here, the next generation of connection matrix, the lx-mat-002 is in the making and will have its own custom PCB to reduce crosstalk and the multiplexer choice will be revisited to provide a better connection for any modular setup!
