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OB-X - Image 1

OB-X

KeyboardAnalogPolyphonic

Introduced in 1979 as Oberheim's bold riposte to the Prophet-5, this synth pioneered a single voice-card design that crammed polyphony into a more portable, programmable package—only about 800 were ever made.

Available in 4-, 6-, or 8-voice configurations, it packs two analog VCOs per voice with classic SEM-derived circuitry using discrete transistors, resistors, and op-amps for that raw, distinctive Oberheim bite, paired with a 12dB/octave lowpass filter, ADSR envelope, and a single LFO. Dual sprung paddle levers handle pitch bend and modulation with intuitive resistance, sitting above a 49- or 61-key synth-action keyboard (velocity-sensitive on some units), polyphonic portamento, sample-and-hold, unison, and chord hold for live expressiveness. A Z-80 microprocessor oversees automatic tuning and 32 onboard patch memories, outputting via a single stereo audio path—no effects, just pure analog tone from its hefty black-panel chassis.

Players still chase its fat, aggressive sound on records from Van Halen to Prince, though some note the original trimpots and components demand careful maintenance today.

Released

1979

Status

Discontinued

Synthesizer
Format
Keyboard
Type
Subtractive
Internal Battery
No
Voice
A/D
Analog
Polyphony
Polyphonic
Oscillators
2
Oscillator Type
VCO (Voltage Controlled)
Voices
8
Filter
Lowpass, 12dB/oct (2-pole), Resonant
Envelopes
2
LFO
1
Effects
No
Expression
Aftertouch
No
Velocity
No
MPE
No
Additional
-
Software
-
I/O
Audio In
-
Audio Out
1 stereo
Headphone
-
MIDI
-
MIDI Type
-
Ports
-
Wi-Fi
No
Workflow
Arpeggiator
No
Sequencer
No
Mod Matrix
No
Memory
32 patches
Measurements
Dimensions
-
Weight
-
Last updated Mar 17, 2026