guitar synth?

[Scott Gravenhorst]

harrybissell at prodigy.net wrote:

>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...

Y'know, I keep seeing this statement and I would agree that it's
response to pitch can never be instantaneous, however, with an
adjustable loop filter, it can be *very* fast.  I discovered
this when I built my PLL freq mult for my FatMan.  People always
say it's slow, but how slow is too slow to be useful?  Whenever
the input pitch changes, the PLL will lag behind (or overshoot 
depending on how the loop filter is designed and adjusted)
causing some interesting phase stuff when mixed with the dry
signal from the pickup.  Much depends on the interval
over which the pitch changes as well.  For 2 octave jumps, I can
adjust my filter so that the PLL is close enough that this effect
is simply part of the attack sound.  For smaller intervals,
the effect can be adjusted almost completely away (from a human
perception standpoint.  You'd still see it on a scope.)

A PLL freq mult is an extremely simple solution.  My main point
here is that of usefulness.  It can be, in fact, quite useful,
and given the level of usefulness, it's a darn good bargain
both in price and in effort.  Imagine building an analogue
perfect octave pitch shifter FOR EACH STRING as opposed
to six 4046 ICs and some 4027s...  Peanuts in comparison.

And let's not forget the fact that bumping the pitch by a 
perfect octave is not the only possibility.  Counters other
than divide by 2 can produce musically valuable intervals 
as well.  Divide by 3 (I have a schemo for anyone interested)
makes perfect 5ths!  Very useful.

I just want to make sure that the PLL gets a fair shake and
reasonable consideration.  After all, do these things have
to be technically/purist perfect?  What in nature is?  I mean
to say that if you are considering making a guitar synth, you
obviously don't want it to sound like a guitar...

-- Scott Gravenhorst : On The Edge, but the Edge of What?
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