Love the Pro 1.
That and a Casio CZ-101 were my first "real", programmable synths. The Pro-one is still my favorite mono. I bought it shortly after the DX-7 came out in the early-mid 80s, and everyone was dumping their old analogs to buy the Yamaha digitals (I had a DX-5 in the 90s - programming that thing drove me nuts). Could have bought a used Prophet-5 from that same store for $450(!) if I had it, and I think I got the Pro-one for about $125.
I had built my first synth from scratch using books and parts from local electronic stores and PAiA. It was very crude looking, but it worked, and I needed a decent keyboard assembly to control it. Buying that Pro-one at the time ended up being cheaper than buying just the bare keyboard assembly from PAiA- and I got an entire synth in the process!
I recently serviced it, and on a whim modified it to add aftertouch to the keyboard. It's pretty cool! I mounted some aluminum channel strip under the keybed with a force-sensing resistor sitting on top of it, and that in turn controls a VCA that all the modulation gets routed thru. I used to have a Multimoog that was touch sensitive, and that inspired the modification.
You can see it peeking out from under the keybed here... I didn't want to drill any holes in the synth, and so I put the bypass and sensitivity trimmer down there as well:
I mounted the VCA inside, just under the bender box:
Did a quick demo of it here, when I was still toying with the idea. I only show it doing pitch bends, but it can control any kind of modulation - FM, Filter, Pitch, or LFO amount...
Love that Matrix 6! A former bandmate had one, and I got to spend a good deal of time with it.
