3080 VCA question

[jhaible]

> Sorry if this has been mentioned before but I was wondering about how
> many dB of dynamic range is reasonable to expect from a 3080 based VCA
> for audio use?

I'd say this depends on the buffer stage at the 3080's output. The optimum
case would
be a plain resistor. The 3080 can source and sink approx. 1mA at its output,
so
choose a resistor value to set your maximum signal level. Now consider the
3080
to be completely turned off, so it won't contribute any noise, and calculate
the
chosen resistor value's own noise. I haven't done the calculation, but I
expect
the resulting dynamic range to be quite good, i.e. not much different from
high
performance VCAs that have a similar output drive capabillity.

SNR will be much smaller than dynamic range, of course. Typical values of
SNR are (from memory, so check the data sheets) around 60dB to 70dB,
depending on the THD you're willing to tolerate.

But you were asking for dynamic range, and this is much better.

JH.