The Oberheim OB-Xa is synthesizer used by Prince in the 1980s. It is part of the OB series that included the OB-X, OB-SX and the OB-8.
The OB-Xa was a further refinement of the OB-X, and was first played by Prince on the 1999 album. The introduction to the song “1999” is an OB-Xa layered with an Arp Omni-2. Prince continued using the OB-Xa on the Purple Rain and Around The World In A Day. It was later phased out in favor of newer synthesizers, but was still in use in 1986, when it appeared on “Emotional Pump”.
He would just put three or four tracks of Oberheim sounds together and use different voicings to make it thick and fat. The Oberheim was the main synthesizer he used in the studio back then. He used the Yamaha CP-80 electric grand too, but for synths, the Oberheim was the main axe. In the earlier years, he always liked to have a real strong lead line tone incorporated into his songs; that was a trademark of his. If you listen to "Delirious," from 1999, there's a real high Oberheim patch with a lot of modulation in there. It’s real lively – kind of a cross between an organ and a square wave.
Dr Fink, Lisa Coleman and Boni Boyer also played the OB-Xas live. It seems that even when Prince was using the OB-8 in the studio, the band preferred to still use the OB-Xa live – possibly because it had a brighter sound that cut through the mix.
References
Brown, Jake. (2010) Prince 'in the Studio' 1975 - 1995.
