Oberheim TVS-1A

Overview

The Oberheim TVS-1A is the production designation of the Oberheim Two-Voice synthesizer, released in 1975 as the first of the company’s polyphonic instruments. It mounts two Synthesizer Expander Modules (SEMs) and a small monophonic-style sequencer in a single chassis with a 37-note keyboard. Each SEM is a complete two-oscillator monosynth with a state-variable filter, and the keyboard assigner lets the player play two notes at once across both SEMs.

Origin & History

Tom Oberheim released the standalone SEM in 1974 and quickly realised that combining several SEMs under one keyboard would produce the first commercially viable polyphonic synthesizer. The TVS-1A was the result; it was followed almost immediately by the FVS-1 Four-Voice and the rare Eight-Voice. The TVS-1A line was discontinued in the late 1970s as the OB-X family arrived with internal voice cards and patch storage. Original TVS-1A units are now sought-after vintage instruments.

How It’s Played

The performer programs each SEM individually using its dedicated panel. Playing two notes on the keyboard sends one to each SEM; identical SEM patches give a clean two-note polyphonic voice, while deliberately different patches turn the instrument into a layered duophonic split for unusual textures. The built-in mini-sequencer records short pitch sequences that can drive one or both SEMs.

Cultural Significance

The TVS-1A is a milestone in synthesizer history as the first commercial polyphonic instrument from a US maker. Its sound, derived from the SEM voicing, has been used across film, television, and rock production for nearly fifty years and is the foundation of the wider Oberheim catalogue.

Related Instruments

• Oberheim Polyphonic – broader family overview
• Oberheim OB-1 – Oberheim’s monosynth contemporary
• Oberheim OB-X – successor series
• Oberheim OB-8 – production successor
• Sequential Circuits Prophet-5 – polysynth that overtook it commercially

Frequently Asked Questions

How many voices does the TVS-1A have?
Two — one per SEM module.

Does it have patch memory?
No — settings are made by adjusting each SEM’s knobs.

Is it the same as the Two-Voice?
Yes, TVS-1A is the production model designation of the Two-Voice.