Alternate Tuning/Just Intonation

#1

Hello all, I should probably mention that I've only just started using the axoloti and am very excited but also completely new to this type of thing save for some very basic projects in pure data.

Anyhow, I'm confused as to how to implement alternate tuning. I'm familiar with the demo patch on the subject, but don't understand what the increments in the tuning table correspond to. It doesn't seem to be hertz or cents or any other pitch unit I'm familiar with. My goal here is to set my keyboard to just intonation (and possible other temperaments along the way). I've searched through this forum quite a bit but can't find any info on it.

Any help would be appreciated! Thanks

#2

the example is just an example of how you could offset pitches, its not a real musical example , ie. of a different scale, as the tuning 'table' is all over the place :slight_smile: the key point of the demo is to illustrate:

pitch in axoloti is a bipolar fractional voltage which is passed into many oscillators (some also take frequency if you prefer), where +1 = semitone (+12=1octave), and midi is translated into this, but you are free to then remap this as you wish because its fractional... so whilst the voltage scale is the normal chromatic with maths or tables you can translate this into alternative tunings.

(this simple demo, is simply taking a chromatic scale, and offsetting it by 1/64s of a semitone from the table, as i said, not a particular musical/useful thing in itself :slight_smile: )

(I assume we are talking about midi_fx/alternative_tuning)

#3

Thanks for your reply! I fell under the weather for a couple days, so I didn't see it until now. It definitely clarifies things for me, though I'll admit that I don't completely understand (again, I'm totally new to this and kind of flying by the seat of my pants).

Is there a way, then, to convert the 1/64s offset to 1/100? I know this can't be done within the table but maybe by using math before or after the table/read function?

Also, what does the math in the demo represent? I've stared at it for a very long time trying to make sense of it, but just can't wrap my head around it. Any pointers on how to musically implement this demo would be very much appreciated. My ultimate goal would be the ability to offset each note in 1/100s as that would allow for the approximation of most temperaments.

The funny thing is that I'm a piano tuner, so I have a pretty solid background when it comes to different tuning systems, but I'm a complete fish out of water here!

#4

sure change the div64 to something else :slight_smile:

the only reason its div64, is the sliders that are being used for the table -64 to 64 (this is fixed) , and the demo represents this as +/- one semitone.

(the c 4 at the beginning is simply to make C be the zero index into that slider table)

as to how to change it, well theres lots of ways, you could simply initialise a table with the values you want (see table help for example) , that way you can just type them in. esp, as ints which you could then divide by 100.

you could even just calculate what 1/100 value are in 1/64 , as you can actually type values into the sliders (select slider, type number with decimal point) 1/100 = 0.64 2/100 = 1.28 i.e. ( N * 64)/ 100

#5

Thank you so much for your help! I ended up calculating the values and typing them into the sliders and it works just fine.

#6

Would you please share your solution?

#7

Sure! I'm basing all of the following off of the factory demo midi_fx/alternative_tuning.

As long as you know how many cents you want to adjust each note, all you have to do is multiply their values by .64 and enter them into the table.

I wanted to tune to just intonation with C as my root note. I used the following list of cent adjustments (these are hard to find, but I knew there was one in the midi manual for my Roland Juno-Gi):

C: 0 C#: -8 D: +4 D# : +16 E: -14 F: -2 F#: -10 G: +2 G#: +14 A: -16 A#: +14 B: -12

Then, multiply each of these adjustments by .64 and type the resultant values into the sliders of the table (the first slider is C and they move up chromatically, you can ignore the extra sliders).

It's not an ideal solution for temperaments, but it works for this specific application. I'm not honestly sure if these cent values are transposable and haven't tried yet, but I would imagine they are (I'm used to tuning with my ear and beat speeds rather than math).

I do wish there was an alternate way of doing it in which one could set specific frequencies for each note in a tempered octave, and there probably is, but that is beyond my knowledge at this point. If anyone else has ideas on that, I'd certainly welcome them!

Hope this helps!

#8

Thanks, that does help. I'm used to doing it by ear too. I sing Hindustani ragas, and have learned to hear two different just intonated flavors of many notes against a tanpura drone. Damn if I know what their value is in cents though. That will require some research. I have this excellent book at home entitled "Harmonic Experience" by WA Mathieu that might answer that question though.