overview picture of the ET-4.1
detail of the wooden intensity keys detail showing tuner connected to instrument detail of side panel with jacks overview picture of the ET-4.1


The ET-4.1 takes the unique au ruban interface of the rare Ondes Martenot and combines it with analog synthesizer circuitry. Each oscillator has six different waveforms, including the classic sine wave of the Electro-Theremin and the Ondes Martenot's unique octiviant and white noise settings. Each oscillator can be tuned separately, or synched to create intervals or interesting harmonics. Oscillator 2 can also be set to a consistent note or used as an LFO to modulate the filter. The internal low-pass filter with variable cutoff frequency is used to shape the sound and this can also be controlled with an external expression pedal or CV source.

A classic spring reverb unit is also built into the ET-4 with mix control ranging from 100% dry to 100% wet. A wide range of sounds can be created with the ET-4; from haunting ethereal sounds and deep bass grooves to sci-fi soundscapes and classical voicings. Every ET-4 is individually hand crafted in Canada using high quality components and select North American Walnut.

Details and Specifications

  • Two independent temperature compensated analog oscillators with sync function
  • Six octave positions for each oscillator covering C0 to C8
  • Six waveforms (sine, triangle, rectified sine/octiviant, 50% pulse, 30% pulse, 10% pulse (white noise on Osc 2)
  • Adjustable ring with metal reinforced wire
  • Replaceable reference keyboard with alternatives available (ex: lapsteel, specific scales, microtonal)
  • Dual wooden pressure-sensitive intensity keys with approx. 3/4" travel
  • Low-pass filter with adjustable cutoff frequency (can be controlled by expression pedal or external CV)
  • Internal spring reverb with dry+wet mix control
  • "Silent" tuner output, switchable between oscillators
  • Line-level (+3db) output with volume control
  • Control Voltage (CV) outputs for ring position (1V/octave) and both intensity keys (0 - 10V)
  • 16VAC power input
  • Dimensions: 30 x 11 x 4"
  • Includes: Printed manual, power supply (110-120V and 220-240V Available) and extension cable.
  • Made in Canada


For more videos, see the ET-4 Series playlist on our YouTube channel.

The ET-4.1 was produced between 2011 and 2018 and has been replaced by the ET-5 Series

For any service, calibration or replacement parts please contact us.

Download Manual [PDF]

Accessories available included our custom Tweed Road Case and matching Expression Pedal & Cord.