[PD] Prime limit sliders

Chuckk Hubbard badmuthahubbard at gmail.com
Mon Apr 4 05:40:35 CEST 2005

> > I'm wondering if this is possible:
> > I want to be able to set the prime limits separately, like how many
> > powers of each prime number up to 17 or so will be allowed as values.
> > Then, the pitch slider will give only values that are fractions where
> > the numerator and denominator are multiples of those primes.
> I don't think I understand what you mean.  But IMHO the step sequencer
> mechanism should be independent from the microtonal scales content.  I
> haven't actually done any work in that direction and will not for
> another little while but my thoughts about this were the following:

It is also possible to use a sampler to assign a different soundfile
to each key, using pre-arranged pitch-bent midi samples; then you can
use that sample mapping in a sequencer.  What I am trying to do
doesn't have a scale, though.

Just intonation is built on natural harmonics, but extended upwards
sometimes to the 13th or higher.  Some folks also build scales and
chords downward... so that, instead of using the harmonics of a lower
frequency, you use all the lower frequencies which share a higher
frequency *as* a harmonic...  The problem is that the number of
possible pitches is infinite, and if you try to nail down which
frequencies you will or won't want to use, there are just too many. 
If you go up to the 5th harmonic- "MI"- then start from there and hit
the 7th harmonic of that, and then take the note which has that as its
3rd harmonic, the ratio to the original frequency is 35/24.  I'm sorry
if I'm making this more complicated than it needs to be.  I want it
completely open-ended.  There are too many possible intervals to
decide on a scale ahead of time.
What I'm talking about with the sliders is having them cycle through
these ratios.  You could set how many times it would multiply each
prime number, like whether 25/24 would be a possible value depends on
what the 5 slider is set to..  I think what Mathieu says is exactly
what I'm looking for, but it'll take me a while to understand it.

> the sequencer part should be configurable in terms of
> steps-per-measure, it would most likley simply output scale degrees
> (should also be configurable to accomodate various scales) with
> optional octave transposition.  the scale would be stored seperately
> (table, data structure, matrix, coll, database, textfile, whatever)
> as a list of (most likely) ratios and the computation of pitch (either
> Hz or MIDI number + pitch-bend) would be done outside of the step
> sequencer mechanism.

I also think the steps should be variable in duration, and 0 should be
a possible pitch value.

> > I'm thinking a/b = c, and the value of c determines the pitch value,
> > but a and b are displayed.
> you mean, the pitch would be c * base-frequency-value.

Right, good catch.

Thanks Michal.


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