[sdiy] VCF schematic

[Tom Wiltshire]

On 23 Jan 2007, at 02:32, Charles Bisaillon wrote:

> I've also had a lot of troubles with the resonance circuit, it doesn't 
> feel
> like it is a linear pot I'm turning, the resonance creeps in 
> exponentially
> as I twist the knob. Choosing the right resistors was a big compromise 
> game.
> I've tried many things but I reach my limit of understanding.

The SSM filters also have a similar quirk going on, so you're in good 
company. The datasheet shows the resonance increasing exponentially as 
the resonance CV increases linearly. The suggested solution is to use a 
reverse audio taper pot and to stick a resistor in series with it to 
cut off the bottom third of the travel where essentially nothing 
happens.

Lovely schematic, by the way.

Tom


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