- Probably the width of the range in which the filter moves.
(Could also be a fixed width with this knob controlling the center frequency (High/Low) of that range.)
- Env / S/H
- Switches the effect to Envelope Filter or Sample/Hold.
- Controls the speed of the Sample/Hold effect.
an Oberheim brochure
The Oberheim Voltage Controlled Filter is an outgrowth of electronic music synthesizer technology. It consists of three basic synthesizer circuits: a voltage controlled filter, and envelope follower, and a sample/hold circuit. When the envelope follower is switched to drive the filter, an automatic "wah-wah" sound is produced. The depth of effect is controlled by a "Range" pot. When the sample/hold circuit is switched to drive the filter, the popular "random filter" sound is produced. The "Speed" pot controls the rate that random samples are produced. The unit is powered by two internal 9 volt batteries. Its dimensions are: 7" wide, 3" high, 6" deep. It weighs 2 1/2 lbs.