I don't know whether or not to post this here, but I was working on mods for my x0xb0x, and then turned my attention to making prototypes, of filters etc., when I came across these, and thought, why re-invent the wheel? This has 3 VCO's 2 VCF's, 2 Audio inputs etc... So I built this (the first of at least 2) to use with my x0xb0x sequencer, I have already made the boards for the second one to use with my second x0xb0x. It is a very good modular unit, which you can make and it goes perfect with x0xen. Instead of modding my x0xen now, I'm going to make a break out box etc., to patch it in with this. Anyone who has Brian's full modded units will probably already be able to do this.
Here is a few pictures of the 'Ultimate' and 'Ultimate Expander', the case is just made from stuff I had around. The wood is a single bed which was built into the house we bought, but made way for a double bed. I removed it and had the wood sitting around doing nothing. The rear drops down on hinges when the back is removed, in order to facilitate any future mods or repairs. The power supply is the 317/337 type with an external 12vAC/0/12vAC centre tapped plug pack plugged in via a 3 pin DIN. These were a good score, they put out ~12VAC @ 1.25A + ~12VAC @ 1.25A perfect for these! It all works but is not calibrated yet as I have yet to build a frequency counter, my old DIY counter is getting to old to use. The second unit should not take as long as this one as I jotted down notes and built both sets of boards simultaneously.
You can see them here: http://www.musicfromouterspace.com/