The Therevox ET-4 (Ondes Martenot Style Analog Synthesizer)

Here’s a quick demo of the Therevox ET-4 analog ribbon synthesizer.

Inspired by the Ondes Martenot’s au ruban controller, the ET-4 is controlled by moving a finger along a reference keyboard shaped to provide tactile feedback. Dual pressure sensitive intensity keys control the amplitude of the ET-4’s two independent analog oscillators.

The video demo is by reader Gil Assayas, who notes, “It is a fantastic instrument with a very deep and musical sound.

“Mine had some MODs added to it, various CV ins and outs, headphones out, a pre-filter FX loop and “hold” knobs for the oscillators,” he adds. “Here’s a demo I recorded today with a few sounds. No processing was done to the ET-4’s raw output, but I used an MXR Carbon Copy delay on some sounds (the reverb is the ET-4’s built-in spring reverb).”

Details on the Therevox ET-4 are available at the therevox site.

9 thoughts on “The Therevox ET-4 (Ondes Martenot Style Analog Synthesizer)

  1. Wow! I’m sure that’s not what a lot of people think of when they hear the words “ribbon controller,” but after having a look through Ondes’ website, I see what’s going on. Very creative use of the electronics!

    I noticed from the site that Ondes says:
    “Bending the plates with a pair of pliers is actually the only method the ribbon controller can be tuned! ”
    If one were to get one of these, does that mean one would have to periodically get busy in there with the pliers? There’s a “tuning” port, but are individual plates expected to go out of tune? Is there some other kind of tuning mechanism implemented?

    Beautiful build quality too! I’m kind of amazed they can hand-build these things to order for the price they’re asking.

    1. Hi, the Therevox ET-4 isn’t an Ondes Martenot clone. In fact, the Ondes Martenot has been out of production since the 80s. Mr Martenot isn’t alive anymore (his name wasn’t Ondes BTW, it was Maurice.)

      Anyhow, this instrument I’m playing in the demo is basically a 2 oscillator analog synth with spring reverb that uses a method of control that is based on the Ondes Martenot controller.
      It’s similar but it’s a unique design, and there’s no plate bending needed as far as I’m aware 🙂

  2. Thanks Gil! I wasn’t familiar with Mr. Martenot’s work before (always more to learn!), but I guess the ET-4 doesn’t need plates as it doesn’t have the “clavier” mode.
    The LC resonance formed by the ribbon track and the roller should still be an integral part of the oscillator’s pitch, though. Maybe you can comment on the tuning stability overall? Does it ever shift a little one way or another under small temperature variations that you’ve noticed? I’m sure it’s no impediment to playing the instrument, I’m just curious as an electrical engineer! Thanks!

  3. Tuning was very stable so far during the few hours I’ve used it (I just received the instrument 2 days ago). Barely noticed any VCO drifting either, but I haven’t tried playing it in an environment with fluctuating temperatures 🙂

    1. Haha 🙂 not that I’m advocating that! It looks far too lovely to treat with anything but respect! Thanks for the feedback, the video’s great. I might be planning a trip to Ontario, I’ll have to try and see if I can sneak a peek in with them 🙂 It’s great that we’re seeing more of these small/boutique companies producing original equipment. Definitely a creative inspiration!

  4. I just too order of one of these as well. It is very easy to use and the sound possibilites are immense. It can get some really thick sounds and being able to control the amplitude of the oscillators separately is a real treat.

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