Oberheim OB-Xa

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Oberheim OB-Xa analog polyphonic synthesizer
Dates1980 – 1982
Technical specifications
PolyphonyMonophonic or 2,4, 6 or 8 voices
TimbralityBi-timbral (keyboard split/layering)
Oscillator2 VCOs per voice
Synthesis typeAnalog Subtractive
FilterSwitchable 12dB/oct and 24dB/oct resonant low-pass
Attenuator2 x ADSR; one for VCF, one for VCA
Aftertouch expressionNo
Velocity expressionNo
Storage memoryYes, 32 or 120 patches
Left-hand controlPitch
External controlOberheim system

The Oberheim OB-Xa was the second of Oberheim's OB-series polyphonic analog subtractive synthesizers, replacing the OB-X with updated features.[1][2]


The OB-Xa was released in December 1980, replacing the OB-X after only a year on the market. The OB-Xa was the first Oberheim product adorned with blue horizontal pinstripes on black background that would become standard trade dress for future Oberheim products. While the OB-Xa offered the same polyphony as its predecessor (4, 6 and 8-voice models were offered), its keyboard could be split into two halves (each with its own voice) or to layer voices to create thicker sound (essentially making two notes sound for every key pressed). The OB-Xa also added the ability to switch between 2-pole 12dB and 4-pole 24dB filtering. It offered Filter Envelope modulation for oscillator 2 (which allows the pitch to be modulated by the envelope) in place of the OB-X's ability to cross modulate (frequency modulation of the first VCO with the second VCO).[3]

Interior view of Oberheim OB-Xa analog polyphonic synthesizer

Instead of the discrete circuits for oscillators and filters utilized by the OB-X, the OB-Xa (and the Oberheim synths to follow) switched to Curtis integrated circuits. This made the inside of the synth less cluttered, facilitating troubleshooting, and reducing the cost of manufacture. It was getting more difficult to service the OB-Xa due to the scarcity of Curtis chips; however, Curtis in June 2016,[4] Coolaudio[5][6] and Alfa[7] all started re-manufacturing some of these chips which has breathed new life into the longevity of the OB-Xa and many other synthesizers that use these chips.


The synth was used in the famous Van Halen song "Jump".[3] Many other 1980s and '90s artists have used the synth including New Order,[3] Carpenters, The Police, Queen, Rush, Rod Stewart, Prince, Miles Davis, Simple Minds and Gary Numan.[8]

Hardware re-issues and recreations[edit]

In 2017, Behringer announced it would replicate the CEM3340 VCO chips used in the OB-Xa synthesizer. The widow of chip creator Doug Curtis released a statement clarifying that the replica was made without permission and that Curtis "would be deeply saddened by the attempt of others to trade on his name and to make unsubstantiated claims of equivalency to his original inventions".[9] In 2018, Uli Behringer announced that Behringer would be producing a clone of the OB-Xa known as the UB-Xa,[10] but a microprocessor shortage delayed the project.[11] The following year, however, Behringer announced that the UB-Xa was ready for manufacture, and announced a desktop version. The first UB-Xa units were delivered in December 2023.[12]

In May 2022, the Oberheim OB-X8, a new 8-voice analog synthesizer with the voice architecture and filters of three classic Oberheim models: the OB-X, OB-Xa, and OB-8, along with functionality and features not included on the original models, was announced. The new synthesizer is manufactured by Sequential in partnership with Tom Oberheim.[13][14]


  1. ^ Vail, Mark (1993). Vintage Synthesizers. San Francisco, California: Miller Freeman Books. p. 154. ISBN 0-87930-275-5.
  2. ^ "Blast from the past: Oberheim OB-Xa - MusicRadar". Musicradar.com.
  3. ^ a b c "The 10 Most Widely Influential Synths Ever". Soundfly. 2016-05-25. Retrieved 2021-05-25.
  4. ^ "Home". Curtis Electromusic Specialties. Retrieved 5 July 2018.
  5. ^ "V3340D Voltage Controlled Oscillator". Retrieved 27 April 2020.
  6. ^ "V3320 Voltage Controlled Filter". Retrieved 27 April 2020.
  7. ^ "Semiconductor production". Retrieved 27 April 2020.
  8. ^ "The Oberheim synthesizer: a playlist". National Science and Media Museum blog. 28 August 2020. Retrieved 2021-05-25.
  9. ^ "Curtis chip company speaks out against vintage synth cloning". FACT Magazine. 2017-03-22. Retrieved 2020-05-21.
  10. ^ https://gearspace.com/board/electronic-music-instruments-and-electronic-music-production/1196469-behringer-ub-xa-synthesizer.html
  11. ^ "Behringer: Chip shortages worsened by Ukraine factory shutdowns, but could be relieved by 2023".
  12. ^ "Behringer's long awaited UB-Xa synth is finally ready for production".
  13. ^ Rogerson, Ben (2022-05-10). "Superbooth 2022: Oberheim is back with the OB-X8, an analogue love letter to its '80s synths". MusicRadar. Retrieved 2022-05-18.
  14. ^ Willings, Sam (2022-05-11). "Superbooth 2022: Tom Oberheim's OB-X8 lands, carrying on the OB legacy from 1979 with help from Dave Smith". MusicTech. Retrieved 2022-05-18.

Further reading[edit]

External links[edit]