Maker.ie were recently invited to showcase at the Irish MATHlete’s Showcase at the CHQ building in Dublin’s City Centre. It was a fantastic day where we got to meet some really bright and interesting young people, and show off what we teach.
The Mathletes had sat a competitive exam in the morning so I decided to create a fun interactive audio exhibit for them to play with, explore, and maybe blow off a little steam. For this I decided to build a 3×3 matrix mixer which would allow for a lot of hands-on audio experimenting by the students.
The 3×3 passive matrix mixer is different from a normal mixer in that each input is connected to each output. This connectivity allows for a number of feedback paths which can instantly and intuitively create rich textures and complex rhythms.
I decided to use our Light Controlled Synthesiser (a simple, light-reactive, hands-on device that anyone can play) as the starting point for generating a sound, then pass it through our Low-Pass Resonant Active Filter which fed into the matrix mixer at input 1. A delay pedal was connected between output 2 and input 2. A loop station with a guitar and fuzz pedal at its input, was connected to input 3. Output 1 connected to an amplifier so the results of all the processing, mashing and mixing could be heard.
To build the matrix mixer there were a lot of connections to be made so I decided to use small strips of veroboard rather than have lots of wires soldered together. This makes for a neater build that is easier to troubleshoot.
The three small bits of veroboard in the middle of the board are connected to the wiper of the potentiometers (via a summing resistor) and carry the input signals. The bit of veroboard at the top is used as the circuit’s common ground point.
The matrix mixer is a really fun piece of kit which I’m glad to have finally got round building. Combined with time-based effects it can turn even the most basic signal source (like the Light Controlled Synth) into pulsing, richly textured soundscapes.
Now, some of that beautiful maths:
- Thom Conaty