An analog, polyphonic synth produced by Oberheim. It was intended as a bold idea to go against the grain of the mid-1990s, by introducing an analog synth into a market that at that point was top-heavy with samplers. However, the development cycle was notoriously troubled, and the synth was marketed in a not-really-finished state, which harmed its reputation and limited sales.
The OB-Mx has a voice architecture consisting of a pair of voltage controlled oscillators, with three waveforms and either of which can be hard sync'ed to the other. A choice of two voltage controlled filters is available: a four-pole filer that is intended to imitate the characteristics of the Moog transistor ladder filter, or a two-pole multimode filter intended to emulate the Oberheim SEM filter. A generous selection of four envelope generators and three low frequency oscillators completes the voice circuitry, along with a voltage controlled amplifier and a ring modulator. Matrix routing allowed the modulation sources to be sent to a wide variety of destinations.
The OB-Mx was package as a rackmount synth; no keyboard version was produced. The basic unit came with two voices, to which voice cards could be added up to a maximum of 12 voices. The synth was multitimbral, capable of playing up to 12 parts simultaneously. Patch memory contained 256 slots, with 64 in ROM and the other 192 in RAM.
Despite these apparent virtues, and its unique place in the market in 1994 when it was introduced, the OB-Mx sold poorly. This is directly attributable to the many bugs and performance limitations in the synth, resulting from the development team having broken down before the design was complete. Oberheim was at the time owned by Gibson Guitars (namesake Tom Oberheim had departed several years previously), and extreme conflicts developed between Gibson management and the Oberheim development team, culminating in the bulk of the Oberheim staff departing in 1992. (Whether they quit, or were fired by Gibson, is disputed.) While lawsuits were filed, Gibson brought in a team led by none other than Don Buchla to finish the design. However, eventually Gibson grew impatient with the progress and decided to take the OB-Mx to market, despite the design still being in an unpolished state. One story that can be found on the Internet about the product's introduction (which may be apocryphal) is that one magazine reviewer, upon taking a review unit through its paces, found it so functionally deficient that he concluded that he had inadvertently been sent a development prototype, and he returned the unit to Gibson without writing a review. Lead software developer Lynx Crowe (who was eventually awarded the rights to the software in litigation against Gibson) suffered a heart attack during the development, and did not get a chance to return to work and complete the software before the OB-Mx went to market.
The reputation for unreliability and bugginess quickly sunk the reputation of what should have been a good product. Probably only about 500 were manufactured before Gibson threw in the towel, not just on the OB-Mx but the entire Oberheim division. They shut down Oberheim, terminating the OB-Mx as well as the manufacture of the Matrix-1000, which was still selling at that point. The OB-Mx wound up being the last product produced by Oberheim. (The later OB-12 was designed and produced by Italian manufacturer Viscount; Gibson merely licensed the Oberheim name to them.) Today, a working OB-Mx is rare and rather valuable on the collector market on sheer notoriety alone; expansion voice cards are impossible to obtain except by buying a unit and stripping it.