Why Wasn’t This Magnetic Cello Made In The 70’s?

[magnetovore] made himself an electronic cello. Instead of pulling a few cello samples off of an SD card, he did it the old school analog way. The finished build is really impressive and leaves us wondering why we haven’t seen anything like this before.

[magnetovore] uses a permanent magnet to play each ‘string’. A lot of details are in this post and [magnetovore]’s provisional patent (PDF warning). From what we can gather, each string is a resistive ribbon sensor connected to a voltage controlled oscillator. The output of the VCO is sent to a variable gain amplifier that is controlled by a coil of wire and the magnetic ‘bow’.

From the video (after the break), [magnetovore] already has an amazing reproduction of the cello sound. It’s a bit electronic on the lowest parts of the C string, but with a little bit of processing it could definitely pass for an acoustic instrument. We’re left wondering why we haven’t seen anything like this cello before. VCOs and VGAs were the bread and butter of the old Moogs and even the ancient ondes martenot. Ribbon controllers were being attached to electronic instruments back in the 50’s, so we’re really at a loss on why a magnetic cello is new to us. If any Hack A Day readers have seen anything like this before, leave a message in the comments.


34 thoughts on “Why Wasn’t This Magnetic Cello Made In The 70’s?

  1. Neat.

    There’s a lot of interaction between the bow and the strings (then simply “sawing” across them – i.e. pressure, angle, angle of attack, tapping, etc), wonder how he’s going to create that.

  2. Awesome! Obviously the next step is to add in tons of pots and switches to shape the tone to exactly what you want…

    Could the resistive strips be adapted to a guitar? Get an accurate volt measurement and an IC (to peg frets to frequencies), you wouldn’t even have to tune it beyond initial calibration…

    1. Yes, that’s right. Now that the basic mechanics are set, I can start fixing up the tone.

      Re adding this to a guitar:
      Cellos are unfretted instruments. The reason I am using these resistive ribbons are because they have infinite resolution, and can have any resistance up to a value, thus an infinite selection of frequency, like an unfretted string.

      Guitars, meanwhile, are fretted in such a way that pressing down in ‘about’ the right area hits just the right way. If you want to use resistive ribbons for some guitar effect, do it. But to replace the strings…. that would make chords Very hard to play.

      1. Yea; but then again is it the amp’s fault it was hooked up to a coil that is a great antenna for receiving energy at the line frequency? Even your body is acting as part of the antenna $50 amp can mean anything from a purchase of a new poorly designed/constructed new product, to the lucky used purchase of a vintage amp. Good luck with the refinements, I can’t help to believe you will be able to produce an inexpensive, usable music instrument that a person can use to produce pleasing music.

  3. Also see the einharp for a platapus of electronic instruments. I and I know I saw a video of a man in a dashiki playing a ribbon controller upright like a cello and kicking major butt, it might have been connected to a Fairlight and it might have been a controller made by zendrum I haven’t had luck finding it but I did see some laser cellos, but that is a different sort of instrument.

    1. Again, I’m not the first to use a ribbon controller. I just put it with a magnet sensor and gave it a good sense.

      The einharp seems to be a usb controller. Very cool, but one of my goal is to keep it as analogue a possible (and then maybe add MIDI at the end).

      I’ve heard of a laser harp, where tripping the laser plays the string, but how, tell me, would you move up and down one string on a beam of coherent light?

  4. Really awesome! I love the analog aspects of the sound. I can’t wait until this this is update and finely tuned. You have a real gem if you can accentuate the analog bow movements more.

  5. 1977: Avant-garde musician Laurie Anderson recorded a violin on reel-to-reel tape, stretched about two feet of tape on a violin bow, and replaced the bridge of the violin with the read head from a tape player. Dragging the tape across the read head at different speeds produced different notes.

    It’s a different mechanism from the one mentioned above — more an analog version of sample playback than direct synthesis — but you could argue that it’s in the same family.

    1. That sounds really cool. It would be hard to control the articulation of the sound thought, right? Did she control volume with her left hand on the neck. It sounds hard to play, but I’m guessing it sounded very cool, especially when switching the direction of the bow..

    1. Well, I got one of those two right.

      My provisional is going to be published in 18 months anyway, and I don’t really think that I will pursue a regular patent. I dont have the capital, and I am well aware that I am going after quite a niche market.

  6. So, off topic since I know nothing about cellos, I do know about violin and violas (same family!). I really don’t believe this could be called a cello. The truth is the complex composite sounds that a violin player can create are currently unable to be created by any other means. I would assume this holds true for the cello. While yes you can recreate the notes you would be unable to create the full composite sound. I hope he can achieve this via an analog method. I am not sure about cello but I wonder if he can somehow recreate natural harmonics.

    1. I agree that there is a big difference between analog and acoustic sound. I can’t quite catch the harmonics of a string because there is no string, just a voltage controlled oscillator. But I think that it could still be called a cello despite the very obvious differences. The purpose was to recreate and expand the method of play of the cello, not to duplicate the sound.

      Right now, the electronics are very simple. But eventually I will make the circuit less noisy and add in more tone control.

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