[sdiy] more pitch shifter thoughts

[harrybissell]

There was a commercial product that did what you describe... it was a
box that made
a single octave of chromatic notes, polyphonic... from a monosynth vco.
It had a single
octave keyboard. Forget the name... someone will remind me :^P

H^) harry

PRCamann at aol.com wrote:

> In a message dated 1/3/2005 11:04:29 PM Eastern Standard Time,
> rtellason at blazenet.net writes:
>
>
>> I got to thinking about this subject some time back,  and came up
>> with some
>> thoughts about things that may or may not work,  I never did get
>> around to
>> playing with this idea.  Maybe you all could tell me why it wouldn't
>>
>> work?  :-)
>>
>> Suppose you took a PLL circuit,  one input to the phase comparator
>> would be
>> some filtered version of your input signal.  (The filtering would be
>> one of
>> the tricky parts,  I guess.)  The PLL is also running a top-octave
>> chip,  and
>> maybe (maybe not?) some divider stages,  depending.  Things get set
>> up so
>> that the lowest "note" available comes out at the same pitch as the
>> filtered
>> version of the input signal...
>>
>> Then you've got the rest of the outputs,  the other "notes",  and
>> maybe
>> octave-related versions of it,  all of which are going to be square
>> waves of
>> course (unless you get one of those oddball top octave setups that
>> produces
>> an assymetric output waveform for higher harmonic content),   but in
>> any case
>> more filtering is going to be needed here...
>>
>> Take a selection of those outputs and you've got "chords".  Mix
>> them,  do
>> whatever...
>>
>> Does this sound like it'd be possible to make it work at all?  If
>> not,  why
>> not?
>>
>
>
> It'll work.  I built a few variations on this idea in the late '70's.
> My favorite was a unit I dubbed the "Uglifier" -- it had a distortion
> section consisting of a Craig Anderton Ring Modulator (from the first
> edition of EPFM) and a Craig Anderton Octave Doubling Fuzz with a pot
> mixing the two signals; a tracking section consisting of a 4046 PLL
> with a 4024 7-stage divider in the feedback loop, with the
> divide-by-32 output going back to the comparator input of the PLL, and
> mixing pots giving combinations of 1 and 2 octaves up and 1 and 2
> octaves down; and a second tracking section using a 4046 and a 50240
> top octave divider in the feedback loop, with a switch selecting the
> top or bottom C as the comparator input (for an octave of notes below
> or above the input tone, respectively) and two rotary switches
> selecting which two of the twelve tones would join the mess at the
> output.  Played a trumpet through this thing --- horribly lovely.
> Still have it around someplace; have to fire it up sometime.
>
> Tried using an old PMOS organ chip in the feedback loop too.
> Overheated quite a bit at the time but it worked.  If I ever dig out
> the chip I'll try again.
>
> Had an idea a few years ago for a stompbox version of it similar to
> the Anderton Roctave Divider, but never got around to building it.
>
> But, yeah, it'll work.  The input conditioning is the hardest part....
>
>
>
> Paul Camann