[sdiy] LM13600 VCA

[Scott Gravenhorst]

The FatMan uses a linear VCA made of 1/2 LM13600.

I have noticed that it will occasionally pop if the
attack time is set to minimum, but I can't say that 
this is control bleed through since it occurs randomly,
probably less than 10% of the time.  It may be that the 
pop occurs if the attack happens to coincide with a 
transient in the VCO waveform.

The V-I converter for Iabc is a typical opamp-PNP type
and they use only one PNP.  I believe that the darlington
is needed only for VCOs for better linearity (and maybe
on a VCF that you'd want to track better).

FatMan schematics are on www.paia.com.



mark verbos <a0284520 at addcom.de> wrote:
>Hi,
>
>I need to make a 16 channel voltage controlled mixer (linear control). I 
>am hoping to use the 13600's I have laying around. I have some 
>questions. Will these be quiet enough? What input resistors should I 
>use? Is there a archetype 13600 linear VCA schematic out there 
>somewhere? Is the single PNP CV path sufficient?
>\
>thanks in advance.
>
>mark verbos
>

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