The OB-X was the first
Oberheim synthesizer based on a single printed circuit board called a "voice card" (still using mostly discrete components) rather than the earlier
SEM (Synthesizer Expander Module) used in
Oberheim semi-modular systems, which had required multiple modules to achieve polyphony. The OB-X's
memory held 32 user-programmable presets. The synthesizer's built-in
Z-80 microprocessor also automated the tuning process. This made the OB-X less laborious to program, more functional for live performance, and more portable than its ancestors. The "X" in OB-X originally stood for the number of voice-cards (notes of polyphony) installed. It came in four, six, and eight-voice models with polyphonic
portamento, and
sample and hold. Even the 4-voice model was expensive at US$4,595. The entire range used "paddle" levers for pitch and modulation, Oberheim's answer to the "wheel" controls of the Prophet-5. Though these controls were never as popular as the standard pitch and modulation wheels, the philosophy was to mimic the motion of a guitar player bending the strings on their guitar. On most other synthesizers the pitch bend wheel was on the left, and the modulation wheel to the right of it; on the OB-X Oberheim placed them in the opposite relative positions. In addition to this unique configuration the polarity of the paddles was distinctive; the player would pull back on the pitch lever to bend the pitch sharp, and push forward to bend flat. == Notable OB-X users ==