guitar synth?

[Hairy Harry]

Hi Toby:

I would not call this easy !!! (inline)


>From: farky <farky at ix.netcom.com>
>To: <synth-diy at node12b53.a2000.nl>
>Subject: guitar synth?
>Date: Wed, 19 Jul 00 00:22:37 -0700
>
>Hey folks.
>
>I've been trying to come up with an elegant way to shift the pitch of a
>guitar signal.  It's fairly easy to do octave up and octave down, but I'd
>like to see something controlled by a potentiometer so the interval(or
>micro-interval) between input and output can be varied.
>
>
>Some ideas I've considered are:
>
>guitar->square wave->div by odd #->mult by even # (adjustable in quantum
>leaps)

Guitar to square wave is really hard to do. The harmonics of the strings 
keep the square wave from ever being 50%.  Thats why most
guitar synths have a divide by 2 circuit included. Only way (I) know
to guarantee a square wave.

If you get a square wave (at 1/2f) then how to multiply it... Plase locked 
loop ?  That's slow...
>
>guitar->sqr wave->freq to voltage->vco w/trim

Can be done for sure. Also slow...
>
>guitar->something that delays the wave at regular intervals of time

Like digital delay ??? These pitch shifters are a little glitchy especially 
with large shifts. And they have a little delay. the more
time you wait, the less glitches.
>
>guitar+squarewave->"and" gate (not fully thought out)

There's a way to double an octave using sine and cosine waves. But
making the "dome filter" will have some delay, and the shift works
only with sine waves of odd harmonics only. Go figure!  See JH's site
for details on his frequency shifter. I'd like an explanation of why
this will only work with odd harmonics ???

Stage 1 IMHO is to get an accurate square wave that tracks the fundamental 
of the guitar, without any octave jumping.  That's what
I'm working on now. I have a working unit but it is way more complex
than you would like for each string (six units ?)

H^)   harry
>
>
>I'll be interested to see what others think.
>
>
>toby
>
>
>
>
>

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