[sdiy] Digital pots as the gain element in a filter

[David G Dixon]

> It's more likely to be a simple analog pot sent through an 
> ADC on the Gaia's MCU/DSP - and the rest of the sound 
> production (including the
> filter) purely in software. The Gaia doesn't have analog 
> filters (digitally controlled or not).
> 
> I would guess that the stepping is caused by the bad 
> resolution of the ADC - forcing the designers to represent 
> the pot position on 8 bits - rather than something in the 
> filter code. Unless filter coefficients are stored in lookup 
> tables with a coarse step size, but today there's plenty of 
> computing power to not have to do that...

Yes, you are undoubtedly correct.  However, given that the parameter which
the pot controls only has 8-bit resolution (for whatever reason), this is
functionally equivalent to controlling cutoff with an 8-bit digital pot, is
it not?  Hence, the observation that such control would be pretty crappy is
still valid, I think.