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

[Matthew Smith]

Quoth Olivier Gillet at 05/07/11 19:01...
> I always thought this was a whacky idea - especially since it would
> give only an approximate expo response through one of those "linear to
> pseudo-audio" pots trick - but someone ended up doing it!
> http://hackmeopen.com/wp-content/uploads/2011/05/Rockit-Schematic.png
> (From: http://www.kickstarter.com/projects/790206393/rockit-8-bit-synth-kit?ref=live)

I saw the same thing myself this morning.

The immediate issue that springs to mind is the fact that digital pots 
work in discrete steps rather than being continuously variable.  Just 
checked the spec for the MCP42050 and found it has only 256 steps which 
would surely be audible whether used to control filters or signal amplitude.

-- 
Matthew Smith

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