Synth DB

The Ultimate Synthesizer Database


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Oberheim | OB-Mx


The OB-Mx is a modern synthesizer module with an audio path that is entirely analog. It has an intuitive and powerful interface which makes it easy for anyone to program their own unique sounds. The OB-Mx claims to deliver the classic Oberheim and Minimoog sounds while being completely programmable and midi compatible.

One historical point is that the OB-Mx is a synthesizer designed by Don Buchla. Buchla has sort of disowned this unit, though. Its filters are actually pretty bad. They don't manage to emulate either the 2-pole Oberheim or 4-pole Moog filters In fact they sound notoriously thin and tweezy. The so-called 'Oberheim filter' provides 12 dB/oct low, band or hi pass filtering, with resonance. And the 'Minimoog filter' uses a meatier 24 dB/oct low-pass filter.

The OB-Mx was one of the few real analog synths, however, available with completely modern features. And because it comes from Oberheim, you can expect great sounds, design, and features. The OB-Mx is highly user upgradeable. Out of the box the OB-Mx comes with one two voice expansion card which contains the two oscillators, 4 multistage envelopes, 3 LFO's, and filters. Up to 6 of these cards can be easily installed sufficiently adding to the phattness of this synth and its capabilities. Unfortunately, the high cost of extra voice cards also made a fully-outfitted OB-Mx a very pricey proposition when put up against other more commonly-available digital instruments of its time. 

Engine TypeAnalog
Voices (max)
LFO3 LFOs (triangle, sawtooth, sample/hold)
Engine Detailed2 per voice; Triangle, Sawtooth, Pulse Width waveforms
Filter (VCF)2 filters per voice; Resonant 12 dB/oct Oberheim type filter with low, band, hi pass and a 24 dB/oct Minimoog low-pass filter section
Envelope (VCA)4 multistage envelopes per voice
Memory256 patches, 256 performances
Key typeN/A
Extra infoStandard 2 voices, expandable to 12 voices
Produced:1994 - 1994
Legend: Obvious Y: Yes, N: No, N/A: Not Applicable
VCO Voltage Controlled Oscillator DCO Digital Controlled Oscillator
LFO Low Frequency Oscillator Sub Sub Oscillator
VCF Voltage Controlled Filter VCA Voltage Controlled Amplifier
Velocity As with a piano, the harder you hit a key, the louder the sound, unlike most organs which always produce the same loudness no matter how hard you hit a key. Aftertouch Pressing a key after you activated it. Channel Aftertouch, no matter which key, it will send a Channel message. Poly Aftertouch, sends the pressure per key instead of the whole channel.
Values for OSC, LFO, Filter, Envelope are per voice unless stated otherwise.

Manuals, patches etc.


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