Oberheim TVS-1 Analog Synth

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"The Oberheim Two Voice Polyphonic Synthesizer contains two Synthesizer Expander Modules, each of which is electronically a complete synthesizer, an eight position, two voice Quantized Mini-Sequencer with Sample & Hold, and a true two voice polyphonic, 37 note digital keyboard.
This combination of electronic music modules allows the synthesizer user to control two completely independent synthesizer voices. For instance, the upper and lower voices from the keyboard can separately be directed to the two Expander Modules for playing two separate musical lines from the keyboard. Or, the Sequencer program can drive one Expander Module while the user plays the second Expander Module From the keyboard. Or, the Sample & Hold can drive one Expander Module while the Sequencer drives the second.

The secret to the Synthesizer’s Flexibility is the Synthesizer Expander Module. Despite its small size (7 1/2″ by 9″ panel size) the Expander Module is a complete basic synthesizer.

The two voice digital keyboard can be operated in either the polyphonic or monophonic mode.

When – operated polyphonically, two separate and independent sets of control signals are available to drive the Expander Modules.

In the monophonic mode, both sets of signals operate when a single key is pressed. This one key depression can then drive four oscillators, two filters and four envelope generators, thereby making monophonic synthesizer sounds previously available only to users of large studio synthesizer.
Two Voice Keyboard Electronics include a three position switch which enables you to select left voice first. right voice first or unison. Also included is Portamento for the left and right voice, a two octave Transpose switch and a Pitch Bend Pot with center detent which covers a two octave range.

The Mini-Sequencer adds greatly to the Two Voice Synthesizer’s capability. Basically, it consists of a dual output, eight position quantized analog sequencer, combined with a sample & hold circuit and voltage controlled clock. The two separate control voltage outputs from the Sequencer can be used to generate two separate melodic lines through two Expander Modules. or one control voltage output can produce the melodic line while the second drives the voltage controlled clock to produce the desired rhythm."