[sdiy] pitch to voltage

[Dave Krooshof]

>on 11/4/01 4:23 PM,  at krooshof at xs4all.nl wrote:
>
>> Then we waveshape 150, 250, 350 etc. into it. A bright 50 Hz is heard.
>> Any ideas on how to do this in (analogue?) hardware?

>If you put a divide by 1.5 circuit in the feedback loop of a PLL, you can
>get multiplication by 1.5 so 100*1.5=150, and so on with the others.
OK. But I'm a little pessimistic. This is how I see the route:
First I have to split up the sound in seperate overtones. Then the deviding
is not a problem. But I'd do the splitting in an Fourier analysis, and having
that it's easy to shift to any pitch. Even then, I'm pessimisic about
being able to distinguish between the seperate overtones. After FFT I'd
just shift the whole lot as one thing.

>Also, if you use a phase shift type of delay,
>(which isn't very practical),
Just my luck.

>you'll get a frequency dependent amount of delay.
Joy!

>I'm not sure those halfway numbers are correct (150,250)
We are discussing a 100Hz input, and we want 50 output.
The 'halfways' are correct as they are part of the list of 50Hz overtones,
which is 100, 150, 200, 250, 300 Hz...
We already have 100, 200, and 300 from the input. Then we do not realy
need the 50Hz, as our ear/brain will derive that pitch in pattern recognition.
To complete the pattern for 50 Hz, adding generated new overtones at
the halfway numbers will do.
So my idea is radical in that respect that I forget about the suboctave
itself, but only trick the ear in believing it was in the air.

I'm hoping that just delaying would be a 1.5 or 0.5 multiplication stand in.