Vintage Synth Explorer

Oberheim • OB-Xa

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!

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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Posting Rules: Please keep your comments relevant! Do not post requests for help, do not use for sales, do not post unless you have something interesting to say about this instrument, or we may delete your post.

 

Seth C Triggs

Posted 376 days ago

I saw this one used by Paul Griffin with Grover Washington Jr., so I'm pretty sure it must've been used in a lot of his studio albums. This is a massive synth and the sounds were great. I know that there was a sort of chime effect used and a steel drum sound, can't place the chirpy effect though. But it was definitely a fat, chirpy effect.

HUMMER

Posted 408 days ago

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Numan

Posted 429 days ago

this synth is the best synth was ever created; fat bassline and fat everything..

tomislav babic

Posted 460 days ago

OB-Xa was made with, at the time, cheaper and more stable Curtis (CEM) analog chips instead of discrete circuitry of its predecessor OB-X. This led to a change in sound which became perhaps less organic, but more agressive and focused, yet retained some of the trademark oberheim character. With oncoming 80s sparkly synth pop, it was just what the doctor ordered.

Some of the albums where OB-Xa was used quite prominently were Jarre's "Zoolook" (1984), Mike Oldfield's "Crises" (1983) and "Discovery" (1984), Simple Minds "Sparkle In The Rain" etc.

imo, its 12dB/Oct filter based on the CEM3320, used in state variable filter circuit, is its number one unique feature. wonderful edgy resonance with level compensation. its easy to dial dark or voxy screaming pads. or add silk to cutting Curtis strings.

here's a few demos i've done on OB-XA. fx used were a touch of plate, and delay on the PWM-LFO example:

http://www.babic.com/SYN/obxa.ht m

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