The Knifonium Vacuum Tube Synthesizer


The Knifonium is a unique 25-tube monophonic synthesizer, with a 4th order ladder filter and a ring modulator. It is currently a working prototype.


The Knifonium was created by Jonte Knif, sho says that the instrument is small and light enough to take to gigs, despite of the amount of electronics, traditional craftsmanship and adequately sized controllers.

Here are the details:


Basic Specs:

  • Oscillator 1 (5 tubes)
    • Sawtooth, Triangle, Pulse, Sine
    • Sync
    • FM
    • Octaves 64, 32, 16, 8, 4, 2 -Coarse tune in semitone steps-Fine tune in +/- 50 cents.
  • Oscillator 2 (3 tubes)
    • Sawtooth, Triangle, Sine
    • is master for sync and modulator for FM
    • Octaves 64, 32, 16, 8, 4, 2 -Coarse tune in semitone steps-Fine tune in +/- 50 cents.
  • Noise (2 tubes):
    • Noise generator is a special tube that is subjected to strong magnetic field. -White, Pink and Red.
  • Ring modulator (3 tubes)
    • Input is sine waves from both oscillators or anything from external inputs, feedback et cetera, drive volume can be adjusted
    • Very wide nonlinear range available.
  • Mixer (2 tubes)
    • A tube op amp, virtual earth mixer with one external input.
    • 3 of the input levels can be modulated.
  • Filter (7 tubes)
    • 4th order ladder filter.
    • Can go from clean to messy to violent depending on levels and resonance.
  • VCA (2 tubes)
    • Transformer coupled variable mu pentode design.
    • More than 40dB of linear range. Capable of total shut down. A switch to increase internal level by 10 dB for extremely nice distortion.
  • Output amplifier (1 tube)
    • Pentode tube, transformer coupled
    • 3 operation modes for different distortions.
    • Provides truly professional transformer balanced output that will drive anything, anywhere.

Here’s an audio demo of the Knifonium in action:

More info at the Knifonium on Facebook.

via reader Joonas Kauhanen

22 thoughts on “The Knifonium Vacuum Tube Synthesizer

    • hot is right, in both senses of the word! awesome instrument, prob gets a little hot with 25 tubes. warm analog sound to be sure. congrats and much success with this inspiring diy project.
      possible ad line (?)-“Knifonium. Cut thru the mix.”

      (sorry… too corny!)

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  1. From the facebook page:
    “The introductory retail price will be around 9000 euros + VAT.”

    I expected that somehow, but still…aww…

    Well-loved. Like or Dislike: Thumb up 8 Thumb down 0
  2. A outstanding piece of engineering, but you could buy a lot of gear for 9 grand. Sounds extraordinary too, although comments about its “warmth” based on a soundcloud link are….interesting

    Like or Dislike: Thumb up 5 Thumb down 5
  3. That 3rd image really does remind me of an 80’s coal effect gas fire..

    Undoubtably a beautiful instrument tho’ ..

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  4. Show me the “3-month-made” schematics & I’ll build one for a fraction of the cost – then design a consumer pcb version for 900euros – what a joke. I’m so Jealous I can’t afford this puppy.. even more jealous I can’t figure out the design on my own

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  5. Good luck with that 900 euros version, because just the components cost more than 2000 euros. :) BTW, there is a recent movie that uses two of the production versions. Not in a central role, but along an church organ.

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