The ESPE01 module adds 2 octaves of range in the bass register of the Moog Etherwave Standard and PLUS theremins. It consists of a small electronic circuit that is installed onto the circuit board of the Etherwave. The installation should only be performed by people with experience in soldering and electronics. (See below)

The unaltered Etherwave theremin usually has a reliable pitch range from 1.5 octaves below middle C to 2.5 octaves above middle C. With the ESPE01 module installed the pitch range will start at 3.5 octaves below middle C, while the high register remains unaltered.

What is very important with any theremin is the linearity of the pitch field. Better linearity means more reliable pitch control. Usually the distances between notes are getting smaller in the high register, and larger in the low register, while in the lowest octave the distances gets smaller again. The ESPE01 module not only extends the pitch range, but also the linearity is improved, and continues into the lowest register.

Additionally the timbre of the Etherwave is a bit smoother when the ESPE01 module is present. This is especially noticeable in the low register, where with the original design the timbre can get quite harsh. With the ESPE01 module installed, the selected timbre is continued in the added low register, giving the Etherwave theremin an even more natural sonic flow to its full pitch range.

The installation of the ESPE01 module is a delicate process. The module itself is installed onto the solder pads on the back of the Etherwave circuit board. Two wires insert the module in the circuitry of the Etherwave via two partly desoldered capacitors the Etherwave board itself.

By buying and installing the ESPE01 module in you Etherwave theremin you indicate that you do so on your own risk, and you take full responsibility. Damage to your Etherwave theremin due to installing and/or using the ESPE01 module will not be repaired by Moog Music or your theremin dealer, and it will not be covered by their warranties. However, there are currently two locations you can have the module installed safely, without losing you warranty. Thierry Frenkel in France and Wilco Botermans in the Netherlands do this for a fee of  25.- Euro plus shipping costs.

Please contact us about the options before shipping your theremin to any of us.

For those installing the module themselves, a detailed explanation of the complete installation process is provided in a video that is available through YouTube. The most recent version of this video is provided here:




 While the Moog Etherwave Pro® is commonly known among thereminists as one of the best actual theremins, many players complain its non-optimal volume response which is often described as “snappy”. That means that even delicate hand movements above the volume loop don't allow to play continuous crescendi/decrescendi from/to zero volume but silence is followed by a jump in volume from zero to a starting level of about -40dB. The consequences are not only a reduced dynamic range but also the impracticality of sophisticated expression at very low volume.

Based on a modification Dr. Robert Moog himself designed to solve this problem, Thierry Frenkel designed the EPVM1345 module. 


 The EPVM1345 module comprises 4 different circuits, each giving another volume response characteristic:

  1. The original circuit, snappy, giving a limited dynamic range of ~40dB
  2. The modified circuit developed by Dr. R. Moog, less snappy, giving a dynamic range of ~54dB
  3. A circuit developed by Thierry Frenkel, no perceptible snappiness, giving a dynamic range of ~61dB. The subjective impression which I had when testing the prototype was a volume response similar to that of my very well tuned and adjusted Etherwave Standard®.
  4. Another circuit developed by Thierry, with a still smoother response, giving a dynamic range of ~67dB. It allows a very sophisticated expression at extremely low volume but exceeds important left hand movement when using the whole dynamic range. :: ::
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