|Dates||1980 - 1982|
|Price||US$4595 - US$5595|
|Polyphony||4, 6 or 8 voices|
|Oscillator||2 VCOs per voice|
|Synthesis type||Analog Subtractive|
|Filter||Switchable 12dB/oct and 24dB/oct resonant low-pass|
|Attenuator||2 x ADSR; one for VCF, one for VCA|
|Storage memory||32 - 120 patches|
|External control||Oberheim system|
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).
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, Coolaudio and Alfa 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.
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".
- Vail, Mark (1993). Vintage Synthesizers. San Francisco, California: Miller Freeman Books. p. 154. ISBN 0-87930-275-5.
- "Blast from the past: Oberheim OB-Xa - MusicRadar". Musicradar.com.
- "Home". Curtis Electromusic Specialties. Retrieved 5 July 2018.
- "V3340D Voltage Controlled Oscillator". Retrieved 27 April 2020.
- "V3320 Voltage Controlled Filter". Retrieved 27 April 2020.
- "Semiconductor production". Retrieved 27 April 2020.
- Crute, Adam (2019-07-01). "Learning the basics of FM synthesis and how it works". MusicTech. Retrieved 2019-11-06.
- "Curtis chip company speaks out against vintage synth cloning". FACT Magazine. 2017-03-22. Retrieved 2020-05-21.
- "Oberheim In Time". Music Technology. Vol. 4 no. 4. March 1990. p. 70. ISSN 0957-6606. OCLC 24835173.