Oberheim OB-Xa

Oberheim OB-Xa Image

The OB-Xa is a massive analog synthesizer with a very familiar and classic Oberheim sound. Its sound, size and power are very similar to the Prophet 5 from Sequential. However this one has up to 8 voices which can be split, layered and stored!

The OB-Xa was available in four, six or eight voice polyphonic models. They all featured patch memories, also in varying degrees. A minimum of 32 patches were available on early models (4 banks of 8). The maximum amount of patch memory storage found on many OB-Xa's is 120 patch memories. All models of OB-Xa, however, featured the new Curtis chips which offered great stability for an analog synth and they are attributed to its great filters and sounds.

The OB-X was very similar to the OB-Xa except that its voices could not be split or layered and, more significantly, the OB-X had a lowpass-only discrete SEM 12dB/oct state variable filter, which had a great and classic Oberheim sound. The OB-Xa changed that in an attempt to economize manufacturing and increase stability by switching to CEM3320 Curtis chips for its filters. The Xa offered two switchable filter modes: 12 dB/oct (2-pole) or 24 dB/oct (4-pole). This hardware change resulted in a more agressive sound, not quite as creamy as the OBX original, but what still became a "bread and butter" sound of the Oberheim line.

Splitting the keyboard mode separates the OB-Xa into two 4-voice synths with two available patches. The Layer mode plays the two patches simultaneously. There are also some added effect sources, perfect for any analog polysynth, including portamento, unison, sample & hold, chord memory and three LFO's!

Oberheim OB-Xa Image

However none of the original OB-Xa's have MIDI, unless otherwise having been modified. The OB-Xa is a classic and fat analog machine. It will give you thick analog pads and drones, punchy bass and cyclic analog effects. It's been used in the past by Depeche Mode, Van Halen (Jump!), Gary Numan, Jean Michel Jarre, New Order, Paul Sheafer, Prince, Queen, Jethro Tull, Stevie Nicks, Sneaker Pimps, Rush, Mike Oldfield, Richard Barbieri, the Thompson Twins and Bon Jovi.

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41 Visitor comments
February 23, 2009 @ 3:37 am
contrary to belief it was a obx through a marshall stack that was used
on van halens jump , not a obxa as in the video, definately superior to
any oberheim released after
February 21, 2009 @ 12:48 am
It lacks proper MIDI (even with retrofit), so I couldn't use computer patch editor that works fine with OB8.
Compared to OB8, oscilators drift alot and that make illusion that synth is rawer, but that 'gift' is not something I very much appreciated by OBXa.
Replacing it by OB8 resolved several key issues incl. important one reliability.
OBXa also lacks some important functions of OB8, so if choice is there opting for OB8 seems as clear choice.
February 13, 2009 @ 6:00 pm
I'm curious to know more about tweaking the trims ... anyone (ron?) know where I can find out more about this?
I'm a little hesitant to just start jamming away at the trim pots because my OBXa is sweet as is...
January 26, 2009 @ 2:17 pm
Just a correction, the obxa has 2 lfo's, not three.One is programmable and the other one is in the modulation section at the bottom left. This synth brings me hours of pleasure, sometimes I could swear it's alive. When I got mine I had to learn how to tune it, and spent a lot of time under the hood. Now I know the voice cards well, and don't hesitate to tweak the trimmers on a voice to give that voice a touch more resonance or envelope modulation or whatever, so that as you cycle through the voices every eighth voice or fourth ( I sometimes kill the bottom 4) you get variation even if you're hitting the same key. Kind of like a four or eight voice, only you have to lift the hood to make changes. Don't be afraid to get in there, you are better off in the end knowing how to fine tune your OB, because as they get older they will need some tweaking. I'll never part with mine, I would swear an oath of vengeance if it was ever stolen.
January 4, 2009 @ 12:55 am
Bought one of these in 1988 for £120.00!!!! (also an OBx for same price) sold both shortly afterwards for a nice profit but always regretted it, could not afford one now. Great synth, good looks, fat sounds, and feels just wonderful to play. really really miss them. Same with a Korg Mono/Poly, which i sold for £30 to get a DX21 of all things, I still have the DX21 which i doubt if i could give away.
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Rated 4.21 (531 Votes)

  • Check Price
  • The link above will take you to an eBay search for this synth to see active listings. If you don't find it there, try looking in our forum marketplace or post a wanted classified.
  • Specifications
  • Polyphony - 4,6, or 8 voices
  • Oscillators - 2 VCO's per voice - pulse or sawtooth
  • Effects - Portamento, sample & hold, chord memory
  • Filter - 4-pole filter with ADSR envelope and switchable 12dB/oct or 24dB/oct slope
  • VCA - ADSR envelope gen
  • Keyboard - 61 keys
  • Memory - 32 patches (4 banks of 8) to 120 memories
  • Control - Oberheim's 'system'
  • Date Produced - 1981
  • Resources & Credits
  • Images from

    Additional info provided by Tomislav Babic.

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