Ambitious MIDI Retrofit project

The Real MC · Joined: Jun 20, 2008 Posts: 62 Location: Painted Post NY

Last month I picked up a barely working OB-SX and proceeded to resurrect it. The OB-SX is a preset only polysynth with no available MIDI retrofit kits. I heard some awesome sounds out of those voicecards and decided they were too good to be relegated to a preset synth.

So I am planning an ambitious retrofit project to replace the OB-SX processor board with a PIC based system implementing patch storage and modern MIDI features like remote editing. Also plan on retrofitting the voicecards with voice modulation and polyAT/key velocity. I want to package it in a rack.

The last time I designed a microcontroller system was in 1988, designed a MIDI keyboard controller around an 8088 for my college EE senior project. I do have some catching up to do on current technology. I am comfortable in assembly language.

This will also be my first project involving PC board design. I'm an EE and have a few books on the topic so I am pretty psyched over this. I'll need to fab the processor board and the voicecard motherboard. In order to implement voice modulation and polyAT/velocity and then shoehorn it into a rack package the voicecard motherboard will have to be a new design.

Finding this forum is a gold mine to say the least - good to see that I am in good company!

This is not going to happen overnight as I am busy with a lot of other things.

jksuperstar · Posted: Fri May 08, 2009 7:27 pm Post subject:

Rather than a PIC, you could also use an Atmel based system, such as the Arduino boards. I think they're a bit more powerful than the PIC (they are very efficient for each clock cycle), and there is a large & growing community around them. So you'd have spare cycles to do any filtering on midi to avoid zippers, or new key maps if your into just intonation.

I mention the arduino, because it's cheap ($35), and there's lots of code around for it, including MIDI. And readily available free tools.