[sdiy] Analog polyphony question

[Scott Gravenhorst]

Many years ago, I bought an inexpensive organ circuit
board.  I think I got it from Jameco.  It had 12 
oscillators on it with a pot to tune each one.  It
also had a 4 output divider chip (TTL) for each oscillator.
I really should have bought several.  I used it as the
sound generator for a rudimentary sequencer.  It worked
very well until one day something fell on my setup (which
was admittedly hastily built and rather cheesey) and 
did something to fry it.  I never got it working again.
I should have just bought a couple more and do a better
job (like put it in a case).  I could see where two of
these could have provided a fat sound if tuned slightly
differently.

Oh well.

harrybissell at prodigy.net wrote:
>The Vox Jaguar used 12 high frequency oscillators with
>divider chains for each semitone.
>
>12 little circuit boards all screwed down across the length of
>the keyboard...
>
>H^) harry
>
>
>>From: Don Tillman <don at till.com>
>>To: phdinfunk at hotmail.com
>>CC: synth-diy at dropmix.xs4all.nl
>>Subject: Re: [sdiy] Analog polyphony question
>>Date: Sun, 12 Aug 2001 21:11:29 -0700 (PDT)
>>
>>    From: "Dr Strangelove" <phdinfunk at hotmail.com>
>>    Date: Sun, 12 Aug 2001 23:27:58 -0400
>>
>>    I was reading recently about TOS based organs, Thomas Organ Co.,
>>    Farfisa, Wersi, etc, The Vox Jaguar used a similer approach but
>>    didn't use a TOS IC so it didn't have JUST square waves I think.
>>
>>What did the Vox Jaguar do?
>>
>>Note that you're not stuck with square waves just because square waves
>>come out of the dividers.  You can sum octaves of square waves to get
>>a staircase, or you can use a cap, diode and resistor to get a half
>>exponential sawtooth.  The PolyMoog actually performs PWM on the
>>waves.
>>
>>    Basically the TOS ICs would divide a 1 or 2 Mhz square wave down to
>>    create the top octave then they would have other ICs to divide by
>>    2, 4, 8, 16 etc for the lower octaves, If you could tune the 1 or 2
>>    Mhz square wave then you could detune two TOS organs from each
>>    other, which would be kinda cool.
>>
>>The PolyMoog does this.  In several different ways.
>>
>>Another thing that the PolyMoog does is that it uses different divider
>>taps on the two Top Octave Generator ICs -- the second TOG chip is
>>clocked one semitone higher than the first TOG chip, and the outputs
>>are all corresponding shifted down a semitone.  This means that there
>>won't be an unnatural sync between the two TOG chips.  That's very
>>clever.
>>
>>(More details on my Moog Patents page:
>>   http://www.till.com/articles/moog/patents.html)
>>
>>   -- Don
>>
>>--
>>Don Tillman
>>Palo Alto, California, USA
>>don at till.com
>>http://www.till.com
>>
>
>
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