A-178 Theremin Control Voltage Source


Regular price $865.00 HKD Sale

Theremin module for generating a variable control voltage by approaching/removing hand to/from an antenna. The distance range is about 30 cm. Additionally the module is equipped with a Gate output with adjustable threshold level. Controls/Inputs/Outputs: antenna input, offset (knob for zero adjust), 2 x CV out, 2 x LED (for CV control positive/negative and zero offset adjust)
To simulate the original Theremin two A-178, a VCO (e.g. A-110) and a linear VCA (e.g. A-130 or A-132) are required. But of course the A-178 can be used to control other functions in the A-100 (e.g. filter frequency, modulation depth and/or speed, tempo, attack/decay time and so on).
The CV output voltage of the A-178 can range - according to the setting of the front panel controls - from -10V...+10V. The gate output switches from 0V to about +10V.

For more detailed information please look at the English user's manual A178_man.pdf


  • controlling any voltage controlled parameter of the A-100, e.g. pitch or pulswidth (VCO A-110), loudness (VCA A-130/131/132), panorama (A-134), filter frequency or resonance (A-120/121/122/123), phasing (A-125), frequency shift (A-126), resonance peaks (A-127), envelope parameters (A-141/142), tempo (A-147)
  • triggering of A-100 activities via gate with adjustable threshold, e.g. starting an envelope (A-140/141/142), Start/Stop of a sequence (A-155), any switching function (A-150/151)
  • Conversion into MIDI control change messages is possible with the  A-192.

Remark: If two or more A-178 are used the distance between the modules/antennas should be at least 30 cm. Otherwise the antennas affect each other.

From August 2012 an improved version for the antenna connector is used. A so-called BNC connector is used to connect the antenna to the module (same type of connector as used in measuring equipment like oscilloscopes). Therefore the price of the module has to be increased a bit. Some mechanical and electrical skills are required to modify an existing A-178 module for the new version of the antenna connector. The module has to be disassembled. An additional hole for the new BNC connector has to be drilled or punched into the panel e.g. right from the existing antenna socket above the Offset control (the existing hole of the 3.5 mm miniature socket cannot be used for the BNC connector). Then the module has to be assembled again and the new BNC connector has to be connected to the old socket. Pay attention that an isolated version of the BNC socket has to be used. For example the BNC connectors UG1094PL, UG1094PR, UG1094W1 or UG1094W2 can be used. In Germany the connectors are available e.g. from www.reichelt.de or using e.g. the order no.  571-5413194-2 from Mouser, Farnell, RS-Online or other suppliers).

Technical Note: It's not possible to connect the antenna via an additional cable to the antenna socket. Antenna and hand form a variable capacitor with a very small capacity in the pico Farad range. The electronics of the module is puzzled out just for this capacity range. If a cable is added the capacity range changes totally and the module will no longer work ! But it's possible to mount the complete module with antenna at the desired position, e.g. into a small case that holds one or two of the modules. For this a longer bus cable is required. If you are not able to manufacture such a cable yourself we may offer a suitable cable upon request. Please tell us the desired length for a quotation of such a cable.

Similar control voltage modules:
Trautonium/Ribbon Controller A-198 / Foot-Controller A-177-2 / Joy Stick A-174-1 / Wheels Module A-174-2