[sdiy] 1v/oct and other scales

[Toby Paddock]

I have a feeling this isn't going to make sense, but...

If I want to control a 1v/oct synth to a scale made up of ratios (1/1, 5/4, 
3/2,... 2/2 or something like that), is there a simple fromula to help me 
find what voltage to add? I know for a regular scale I'd just add 1/12 volt 
per note. But what about crazy intervals?

And the rest is just blabbering...

I don't have access to any hardware right now or I could just try it and 
measure. Also, I don't know how a scale based on fractions sounds. Should 
look good on a scope though.

Also also, I'm wondering about adding these voltages. For a normal scale, I 
could add and subtract voltages like 1/12v + 3/12v - 2/12v... and it would 
jump around on notes and sound OK.

But if I add voltages needed for ratios like above, would the ratios 
multiply? Would it sound nasty? Should look good on a scope though.

Maybe it's as simple as converting a ratio to octaves, and multiplying that 
by 1V?
oct= log(ratio)/log(2)        (either log or ln)

1/1 -> 0V
2/1 -> 1V
3/2 -> log(3/2)/log(2) -> ~0.585V

Or am I missing something?

Thanks,
Toby