The Ondes Martenot; Better than a Theremin

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[Ville] loves the sound of an ondes martenot and decided to build his own. No, it’s not made of vacuum tubes like a 1920s original, this one is made out of a cheap, off-the-shelf analog synth and just a few extra parts.

The ondes martenot is a theremin-like musical instrument; instead of waving your hands around aerials on the theremin, the ondes uses a small ring attached to the player’s finger on a wire loop and a volume lever. The ondes isn’t a common instrument by any means, but Radiohead uses one¬†several¬†in any event.

[Ville] began his build by taking a small, cheap, and new Korg Monotron analog ribbon synth, cracking it open, and reading the schematics. A 100k multiturn pot was wired into the monotron and fastened to a printed paper keyboard with a system of pulleys and a small metal ring. With the multiturn pot wired into the pitch input on the monotron, [Ville] had a semi-accurate and very functional ondes martenot replica.

You can hear [Ville]’s ondes in action after the break. It’s a little rough starting out, but by the time he’s looping multiple phrases it really does sound wonderful.

12 thoughts on “The Ondes Martenot; Better than a Theremin

  1. The NFB produced a great doc about this, worth watching, great hackery inside! including attempts to reverse engineer the special component of the original

  2. cool

    i’ve made an ondes martenot midi controller, however when i finished it i realized the volume key wouldn’t play the note when my hand started a note on the right side of the keyboard,..(probably something in software) i may try to fix it someday

    i also used a multiturn pot, but had the pullys vertical and put a bit more effort into the key mechanism yet it still wasn’t like a real key from an ondes martenot (if anyone knows how that works i’d like to know)

    what’s cool about the ondes martenot is not only the ring/string but the keyboard you could use vibrato on each key and also the three resonators (with a kind of spring, plate and sympathetic string reverbs)

    1. in looking around for ondes martenot stuff last night i found this project which is done very well:

      his site is in japanese but you can use googletranslate to get the jist
      he even posts the arduino code which i will definitely be trying out

  3. And its even a true stringed instrument! Is he pressing anything or is it just finding the position of his right hand?

    1. the string isn’t vibrating or creating the sound, it’s attached to a multiturn potentiometer which sends CV to the synth (it’s purely electrical)

      position with the right hand, volume with the left

  4. If done with a 1volt per octave analogue synth the scale will be even. This looks like it is an actual string instrument finger board. I don’t like to do one thing with two hands separated and radically different. I would put the volume as I do with the steel guitar right in the slide. One handed perfection. I have 10 turn pots and an Arp, one more project on the back burner.

  5. Hi!

    Actually Monotron has linear to exponential conversion. But it’s not perfect 1volt/octave. I think it’s possible to make the scale more even with anti-log trick:

    http://www.geofex.com/article_folders/potsecrets/potscret.htm

    But I like the fact that the “keyboard” gets thinner in the higher octaves like in stringed instruments. I get more violin like vibrato that way.
    I’m not yet revealed this in my blog but the volume controller is done with LED shutter and LDR. It’s optical just like those Morley volume pedals.

    I don’t use a looper pedal. It’s VST effect called Angstrolooper

    http://plugins.timeshard.com/angstrolooper/

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