images via this auction"The OB-X was released in 1979 and was the first programmable polyphone synth from Oberheim. It's the direct successor to the famous SEM-based four/eight voice. The main point is, that the OB-X has the same discrete filter design as the SEM-modules - there are no curtis filter ICs as the followers OBXa and OB-8 got. But the filter is not as flexible as the SEM-one (which were multi mode) - it has a fix 12dB lowpass setting. When you open the belt, you will see boards with tons of electronics. Every voice has got it's own circuit board - they can be removed separately. A maximum of eight voice boards can be installed - mine has got six. For stereo use, every board's output is assigned to a pan pot. Every voice board has two VCOs with saw and pulse. The VCOs can be synced and crossmodulated (you won't find crossmodulation in the followers OBXa and OB-8) - so there can be generated strange and metallic waves. There's a great polyphonic portamento section, an autotune function and a hold button (which can be used as a chord memory as I found out!). Then we got the described filter section and two ADSRs for filter and amp. The sections can be modulated with the Oberheim-typical modulation matrix. An LFO with quare, triangle and S/H can modulate the LFO pitch, the filter cutoff and the pulse width (separate for VCO1 and 2). There are 32 memory locations to save your sounds. Of course you can edit programs any time - just push the edit button and turn the knobs as you like. There's a casette interface to load and save memory banks. On the backside you find some goodies: a CV/Gate interface to control voice 1 and a filter control jack, where I've connected an external potentiometer to modulate the filter cutoff without any stages - which sounds absolutely great. This direct and precise cutoff control you will never ever experience with a software synth. You can really navigate to a particular partial tone and hear it growing louder until you got it exactly! What I learned to appreciate furthermore are the Oberheim-typical levers. They allow you to bend the tones of the Oberheim like you bend a guitar string - the levers are very responsive. It's easy to bend up a note and modulate it at the same time. I admit freely: I'm not a fan of wheels - I like better the korg joystick. Unfortunately, the Oberheim-concept has been abandoned."
