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
June 8, 2011 @ 11:49 pm
Lets not forget that this montster was all over Cyndi Laupers Mega Hit Record "She's So Unusual"
And Laurie Andersons intricate "Big Science" OB-Xa = Classic, Beautifully Sounding Polysynth this is to be sure...~ Hopefully I will be playing one before too long as I believe its right up there with the Prophet 5s and Jupiter 8s...
May 8, 2011 @ 10:13 am
Another 1984 interview with EVH mentiond that he did have an Ob8 during the recording of 1984 but that he preferred the warmer sound of the Ob-xa. He goes on to mention that his Xa was out for repair during the session for tuning issues. Not sure if the Ob8 made it on 1984 but I would not be surprised a few small parts and overdubs were the ob8. "I'll Wait" was a factory obxa patch and "1984" was patches c3 and c4 split. Jump was a tweaked version of patch A1 with dual saw's and cutoff/resonance tuned to taste. The key to the Ob-xa sound is the slight tuning instability between the oscillators
May 6, 2011 @ 3:32 am
The patchbook with the 120 patches in high quality PDF and JPG:
April 28, 2011 @ 11:02 pm
In the April '84 issue of "Keyboard" Eddie Van Halen says that on the studio recording, he used the OB-Xa in split-mode for both "1984" and "I'll wait". On "Jump" and "1984" the OB-Xa was recorded direct in stereo through a chain of various effects whereas on "I'll wait" (for which he wanted a nastier synth sound) it was recorded through a couple of Music Man amps.

The article also mentions that for the tour Eddie used two OB8's instead of the OB-Xa.
March 26, 2011 @ 11:38 pm
A bunch of these comments are dead on regarding the OBxa tuning stability. If you replace ALL 7 electrolytic caps per soundboard, you are in business. When the caps are replaced and the cards re-tuned, the OBxa will stay in tune cold, warm, and hot WITHOUT having to hit autotune. If you are hitting the auto tune every 10 minutes and have voice boards occasionally fail, grab some 15uf or 22uf caps, a solder [beep] er, grab your iron and go to work. Promise you that in 3 hours your OBxa will run like new! Might as well replace the filter caps and the rest of the tantalum and electrolytic caps too!
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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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