[sdiy] Quick query about 2164 VCAs

Neil Johnson neil.johnson71 at gmail.com
Sat Mar 16 23:15:38 CET 2019


Hi Matthias,

> Another quick answer: I don't see why.
>
> How could the current know that it should be divided into two equal parts?
>
> This reminds me of the discussion last year about paralleling 2164s. I'm using three 2164s in parallel with a separate Rin for each VCA, and somebody said that those three resistors could be swapped against one common resistor feeding all the VCAs. I was then asking how the current into a virtual earth (or even worse, three less than perfect virtual "earths" that sits on three slightly different voltages) would know that it would split into equal halves, but IIRC there was never an answer to that. :-)

This kind of ended up at the current version of the SSI2164 datasheet
which shows how to connect multiple cells in parallel.  Yes you can
connect the inputs in parallel, and you scale the compensation network
accordingly.

I suspect, however, that this arrangement only works if all the
paralleled gain cells are working at the same CV and that all the
outputs are also paralleled.

Neil
-- 
http://www.njohnson.co.uk



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