spec for sending scales / chords?

I there a standard / spec for sending scale info over a cable? I think I’ve seen some discussion between @k-chaffin and @DaveVenom about that maybe?

There is the “poly external scale” Aria proposed standard from way back, which is the default I use in my modules. Other modules such as the Aaron Static modules do not use this standard. My modules have the option to output the scale in the Aaron Static format.

The poly external scale format is just a 12 channel output (or input) for the 12 semitones and sets the CV to 8.0V if the semitone is in the scale, 10.0 volt if the semitone is the root of the scale and to 0.0v if the semitone is not a member of the scale.

Wouldn’t there most logical approach be to see each note of the scale or cord as a different v/Oct on a different channel is the cable? That way a polyphonic voice could play it?


Actually, I was not thinking correctly about this. My modules’ settings to talk to Aaron Static modules were related to circle of 5th “degrees”. For scales, I should have said that I can send the poly external scale format directly to the Grande Quant module via my menu setting of Heptatonic Chromatic Scale 12-channel output.

I also support scale output in the following formats:

  • Heptatonic Diatonic STD-7ch
  • Pentatonic-5ch
  • Pentatonic Chromatic-12ch

Of course my Meander based modules only use the modal scales which can each be transposed via the “root”. The Pentatonic output devives a pentatonic scale from the current modal scale using a common practice scheme.

My first question would be: what constitutes a scale? Are you assuming 12note et from the beginning?

my particular case its definitely 12TET. but just kind of curious what’s out there.

I’m looking forward to seeing what you may do along these lines. It is a topic close to my heart. Last week I played quite a while with the harmonic minor and melodic minor scales, in addition to my modules’ use of natural minor. We really do not have the modular tools to support this at present. I ended up requantizing my natural minor music to the harmonic and melodic minors, but that does not always come out like I want. And of course the melodic minor usage is somewhat difficult to understand in music. It seems to me that the melodic minor is usually used as a key (or scale) transition such as from major to minor or vice versa with an intermediate melodic minor transition. But, this is beyond my music theory and common practice expertise.

Yeah, doing minor “correctly” is, as you say, quite difficult. Doubt that I will be tackling that!

Well, I’m interested in hearing about whatever you are considering :wink:

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Is this a case where you could leverage the Tipsy protocol for sending arbitrary data over cables?

I can imagine a variety of ways of encoding a scale, even if just in text.

Of course, so far as I know, only the BASICally and TTY modules can understand it currently…so not currently useful to you.


I took a fairly close look at Tipsy a few weeks ago. I can imagine it being very interesting to develop more modules that could use it in one way or another.

reminds me of midi system exclusive data…

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Not dissimilar just it travels on a cable

Exactly! I used midi sysex a lot in my original Meander program. I’m always imagining doing something similar in Rack.

I mostly agree with Andrew, except I think all but the root note should be specified as intervals. The first channel specifies the scale root, the 2nd channel the interval to the 2nd note, 3rd channel the interval to the third note, … and the last channel the interval to the last note of the scale, which becomes the root of the next scale in the series. The number of channels on the cable determines the scale length.

By convention, the root note would be a bipolar interval from C4. Each interval can either be relative to the root, or relative to the preceding note. One advantage of being relative to the root is you can simply add the root to each scale interval to get the entire scale. Change the root, and you change the key of the scale.

The big advantage of this system is it can represent absolutely any fixed scale (no melodic minor) up to 16 notes long using any tuning you desire on a single polyphonic cable. It need not be octave repeating, and it could be any form of just intonation. Of course it can represent “standard” 12ET, but doesn’t constrain you to that tuning.

I did something very similar with my Venom Non-Octave-Repeating Intervallic Quantizer (NORSIQ), coupled with my NORSIQ Chord to Scale. The Chord to Scale module receives any polyphonic “chord” and sorts the notes into a scale. It then transmits the scale to the NORSIQ via three cables instead of one. The root note is on one mono cable, the scale length on another mono cable, and the intervals on a poly cable. Because of how the NORSIQ works, the intervals are all relative to the previous note rather than relative to the root. The NORSIQ is restricted to a total of 13 intervals, so a maximum scale length of 14 notes.

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