[sdiy] the obscure output of a 2164

David G Dixon dixon at mail.ubc.ca
Sat Mar 11 01:58:16 CET 2017


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.



> -----Original Message-----
> From: navelludd at gmail.com [mailto:navelludd at gmail.com] On 
> Behalf Of Mattias Rickardsson
> Sent: Friday, March 10, 2017 1:37 PM
> To: David G Dixon
> Cc: Busby Bergson; Synth DIY
> Subject: Re: [sdiy] the obscure output of a 2164
> 
> On 10 March 2017 at 02:35, David G Dixon <dixon at mail.ubc.ca> wrote:
> > Their outputs can interact with each other in unpredictable ways
> 
> Do you have any example to share? :-)
> 
> /mr
> 
> 
> 
> >> -----Original Message-----
> >> From: navelludd at gmail.com [mailto:navelludd at gmail.com] On 
> Behalf Of 
> >> Mattias Rickardsson
> >> Sent: Thursday, March 09, 2017 2:48 AM
> >> To: David G Dixon
> >> Cc: Busby Bergson; Synth DIY
> >> Subject: Re: [sdiy] the obscure output of a 2164
> >>
> >> On 9 March 2017 at 07:53, David G Dixon 
> <dixon at mail.ubc.ca> wrote in 
> >> his nice beefy 2164 description:
> >> > However, be careful about using 2164s in parallel, as 
> they will not 
> >> > retain independent control (I learned this the hard way as well).
> >>
> >> Interesting, what kind of problems have you encountered here? :-)
> >>
> >> I've used parallel 2164s for years and never noticed 
> anything strange.
> >>
> >> /mr
> >




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