[sdiy] the obscure output of a 2164

David G Dixon dixon at mail.ubc.ca
Sat Mar 11 05:18:25 CET 2017


I made it work (with one very cleverly controlled 2164).  That's the basis
of the Intellijel Quadra circuit. 

> -----Original Message-----
> From: rsdio at audiobanshee.com [mailto:rsdio at audiobanshee.com] 
> Sent: Friday, March 10, 2017 6:02 PM
> To: David G Dixon
> Cc: Synth DIY
> Subject: Re: [sdiy] the obscure output of a 2164
> 
> Is a VCA really equivalent to a voltage-controller resistor 
> in all aspects?
> 
> In other words, transconductance is not exactly the same 
> thing as transresistance.
> 
> Harry Bissel's Morph-Lag shows the two potentiometers with 
> open connections on one end of each. Is it even possible to 
> run a VCA in an equivalent manner?
> 
> Brian
> 
> 
> On Mar 10, 2017, at 4:58 PM, David G Dixon <dixon at mail.ubc.ca> wrote:
> > I tried to use to different 2164 VCAs as variable resistors 
> to control 
> > the attack and decay independently in a Morphlag circuit, 
> and the two 
> > VCAs interacted strangely such that I couldn't independently adjust 
> > one without affecting the other.
> > 
> > In addition to the two 2164 VCAs having their outputs both 
> feeding a 
> > common Miller integrator inverting input, their inputs were also 
> > treated fairly unconventionally, with 1k resistors and 
> diodes pointing 
> > in opposite directions.  I think it was more the inputs 
> that were the 
> > problem than the outputs, because I have used 2164s with 30k input 
> > resistors and outputs tied together in many circuits (including the 
> > Rubicon) and this seems to work well.
> > 




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