Background to set up my question: My first synth was a Prophet 5, purchased in 1981 (I don’t even know which Rev it was). I discovered that for my playing style, a filter expression pedal was a game-changer, and I used the pedal all the time. I’m pretty sure the pedal I used at the time was CV. When I leaned into that pedal the synth would growl and was so expressive, just as if I was turning the knob on the panel. In 1983 or so I bought an OB-8 and I used a pedal in the same way and I had the same experience, where leaning into the pedal was just as if I was turning the knob on the panel. However, there was one problem with the OB-8/pedal – just plugging the pedal into the OB-8 overrode the filter cutoff setting for each patch. Fortunately, I found someone to perform a mod to the OB-8 by putting a little switch on top that would engage or bypass the pedal, so I could switch modes easily.
Over the years my life took me in other directions and I sold off my gear. Over the last few years, I am getting back into synthesizers and I now own a Prophet 10 Rev 4 and OB-X8. I use an expression pedal to drive the filter cutoff on each but it is disappointing, it is just not the same as my original experience. I can’t get that ballsy growl, just a clinical sound that is a little steppy. It seems as if the pedal input is getting converted to MIDI or something inside the synth.
Thanks for reading this far – here’s my question: Is it possible to accomplish a true CV connection to the filter cutoff like my original synths? Or has anyone found another solution?
(I’ve posted this to both the Prophet 10 and OB-X8 boards.)