Jack Hertz 975 Report post Posted May 5, 2017 The four square knobs are octave switchers, and the others seem to effect timbre, frequency and resolution. The knob on the far left has a different top slider, so I dont know if it is missing a cap, or if it is designed that way. It functions fine. These things are just so rare that I cant even find another photo to compare it to. There was an EB 250 for sale a few years back, but that was a lower end model version of this one. View full synthesizer Share this post Link to post Share on other sites
