Yamaha CS80

Yes, I have that set of Yamaha engineering notes.  In fact, that page
you indicated was my primary guideline for the discrete version.  I think
the reset pulse is to guarantee a full waveform reset (full capacitor
recharge) at the higher frequencies such that the pitch doesn't start to
go flat.

  That page also shows why tracking of the VCOs is such a pain; the 
transposition setting resistor (Rft) has to be exact for each desired 
octave, which is why there are trimmers for each one.  If the Rft value 
for a given octave is off even slightly, the tracking goes south.

  I have my prototype CS VCO running into my production CS filter.  It 
sounds very nice. :)  I'll record some audio clips this weekend.

  In other news, I built and tested the NE11000 VC-BPF as used in the 
GX-1, and it works great..except that I wired the resonance pot backward.  
(The original NE11000 did not have a variable resonance control; it only 
had a trimmer that was set and sealed for a Q of 4 or so).

Crow
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On Fri, 27 Aug 2004, David Rogoff wrote:

> I just found this site: 
> http://home.debitel.net/user/jhaible/cs80_vco.gif.  Apparently, the 
> weird pulse is done on purpose!
> 
>  David