Circuit Bending

Circuit Bending a GEM PX3: Part 1

1st of May, 2017 - Edited: 14/05/17


A few weeks ago, I was invited to join the Western Australian Small Keyboard Orchestra, or WASKO for short. One of the requirements for joining was to obtain a basic musical keyboard which has internal speakers and the ability to run on batteries. Since I didn't already own one, I had to search around my local area for something used. After about 30 minutes of searching online, I found somebody selling their GEM PX3 for $20! I quickly researched the keyboard online to hear how it sounded, and for $20, it sounded brilliant!

The keyboard includes 48 voices and 48 rhythms to play around with. Since this is a PCM based keyboard, I suspect that many of the voices were sampled from the Yamaha DX range of synths. One of the things that really surprises me about this keyboard is that it has MIDI. This means I'll be able to use an external sequencer to create music with it. I might even be able to create 16 track songs! Unfortunately, my excitement quickly diminished as the MIDI capabilities are very limited.

For starters, the keyboard only recognises note-on and note-off. This means I won't be able to use pitchbend, modulation, and other CC messages. Velocity information also isn't recognised. Another thing which annoyed me was that the keyboard only recognises notes within its physical range. This means that I won't be able to use an 88 key midi controller as all of the notes outside of the range won't work. The final limitation is that only MIDI channel 1 is recognised, so I won't be able to sequence multiple tracks. To be fair, for a $20 keyboard, I didn't expect this to work anyway.

At the moment, I haven't started the circuit bending process, but when I do, this page will be updated with pictures and documentation.