The Oberheim 4 Voice is a polyphonic analogue synthesizer used by Prince. It appears on For Youand Prince.
It was the first true polyphonic synthesizer (capable of playing chords) and lead to the development of the Oberheim OB line (OB-X, OB-Xa etc.) that Prince used throughout the 1980s.
Polyphonic synthesizers — those had just started happening. They had the Polymoog, but it had only been out a year, two years tops. They were pricey, and they didn’t do a lot yet. The Oberheim four- or eight-voice SEM — they were called the SEM Module versions, basically equivalent of a Minimoog, which you could only play one note at a time on... He had all this state-of-the-art gear when I went into that audition.
Prince used the keyboard for its distinctive brass, lead sounds and effects. It can be heard on the songs "Soft and Wet", "Baby", "My Love Is Forever", "I Wanna Be Your Lover", "Why You Wanna Treat Me So Bad", "I Feel For You".
It was also used live by Dr Fink and Gayle Chapman.
4 Voice multitimbral
8 x VCOs (Two per voice), pulse and sawtooth waves with pulse width modulation