The Solafide Forbes Nash Organ


A few years ago, [Chad] wanted to build a musical instrument. Not just any musical instrument, mind you, but one with just intonation. Where modern western music maps 12 semitones onto a logarithmic scale per octave, just temperament uses ratios or fractions to represent notes on a scale. For formal, academic music, it’s quite odd especially if you’re building an analog synth for this temperament. In a remarkable three-part write up (parts one, two, and three), [Chad] goes over the creation of this extremely strange musical instrument.

The idea was for this synth to produce sine waves for each of the tones on the just intonated scale. [Chad]’s initial experiments led him down the path of using strings and magnetic pickups to produce these sine waves. These ideas were initially discarded for producing sine waves electronically on dozens of different homemade PCBs, one for each tone.

The keys are an extremely interesting design, working on the principle of light from an LED shining on a photodetector, blocked by a shutter on a spring-loaded key made on a laser cutter. The glyphs on the keys seen above actually have meaning; each one describes the ratio of the interval that key plays, encoded in some schema that isn’t quite clear.

What does it sound like? There’s three videos below, but because this synth isn’t tuned to the scale you’re used to, it doesn’t sound like anything else you’ve heard before.

31 thoughts on “The Solafide Forbes Nash Organ

  1. Slightly less repetitive than Peter Glass. Significantly more grating. It would be great for generating video game music and SFX – in fact, I thought that some segments of the second video sounded like some classic Super Mario music. I’m glad he likes it. And Andre’s dogs. Cool project overall. If anyone needs me I’ll be listening to my “modern western music.” :)

  2. Not much for all that good work. I was expecting more harmony considering the more harmonically correct that just is. Early music, renaissance, and much baroque are at home with just. Digital ‘pipe’ organs can play many temperaments nowadays.
    Little clips on first vid, the rest need “Warning Clipping Max Loud” posted by HaD! Cameras with built in mics need talked to only, no guitar amps.
    With ZynAddSubFX and Scala you can explore the world of music that ain’t “PC-ET”, both are free. You can even play it from the qwerty.

  3. THe last video is great! sound like something coil could have written. (NOT lacuna coil)
    Didn’t this instrument have some whole threads on the 4chan/diy imageboard?

  4. WTF? Bizarro page is bizarro. The whole linked blog is *images* of text, with some genuinely bizarre styling that manages to crash Opera (12) on load, and crashed Chrome when I resized the window.

    1. The images of text are the output of his homemade word processing software, which is an interesting project on its own. Not sure why it’s crashing your browsers – no problems on my Chrome (desktop or mobile).

    2. The images of text are the output from his homemade word processing software, which is an interesting project on its own. As for the crashing, the pages work fine on my Chrome and Firefox – not sure why it’d bork both of your browsers.

  5. The fact that this instrument sounds weird has almost nothing to do with the temperament (which is a subtle difference in the way groups of notes sound played together), and everything to do with the tone generators and effects used.

    1. The tones themselves are fine, I think – in the very first demo it’s not bad, because the tones are held for quite a long time, so you don’t hear the distortion caused by them cutting in and out. Switch bounce, maybe? Dunno.

      Then again, having a sine wave oscillator you have to tune two components to get the frequency and shaping right isn’t exactly ideal. There’s an old app note from Linear from Jim Williams for producing sine waves that I’d go with – that one’s ~percent level distortion, which I don’t think you can beat.

  6. My kids made similar random noise and screeches when they first started playing instruments (or stepped on the cats tail) – luckily the lessons eventually took hold and they started playing music.

  7. “The glyphs on the keys seen above actually have meaning; each one describes the ratio of the interval that key plays, encoded in some schema that isn’t quite clear.”

    Is it just a coincidence that these glyphs look strikingly similar to Hangul? The language was written to look as it sounds.

    1. Equal intervals are simply out of harmony. It don’t mater how many per octave, equal sucks. Balinese tuning sounds weird to western ears but it is just as mathematically precise as the rest of the intervals, just higher up the interger scale of harmonics.

  8. Ugg!

    I had problems getting past the badly overdriven audio. After that, I couldn’t recognize anything that might resemble a melody. It was barely more than a repeating pattern of beeps.

    I suspect that “detuning” a contemporary keyboard would sound better simply because some thought had been given to features such as attack, sustain, (release?), and decay, as well as filtering.

    Even DTMF tones sound better.

    [haineux] (above) refers to Easley Blackwood’s “Fanfare in 19-note Equal Tuning”. This is at least tolerable… and weird.

  9. This is nonsense! Never read a blog as pedantic as this!!! The video songs are really – and I mean REALLY – bad. And Chad clearly don’t understand what he is doing: a lot of synth can be tuned to just intonation (Shruthi for instance is a very cheap and great sounding alternative).

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