[sdiy] Filter problems

Rutger Vlek rutgervlek at gmail.com
Sun Jan 28 14:47:37 CET 2018


Just out of curiosity, would it also help to make the resonance path AC-coupled (rather than a DC path)? It avoids DC in the filter building up, although I can imagine offsets that interact with cutoff frequency to become problematic.

Rutger


On 27 jan 2018, at 17:28, Tim Ressel wrote:

> Hi,
> 
> Filters can be a pain. I've got one that is misbehaving. Here is a link to the schematic:
> 
> https://www.dropbox.com/s/acjvwb17nmuok1n/PrismFilter.pdf?dl=0
> 
> At low CVs it filters fine, but as the freq cv hits around 2 volts the behavior gets odd. I start seeing a rising DC bias on all the outputs. At about 3 volts all the outputs rail positive.
> 
> Any help is appreciated. Thanks for playing!
> 
> -- 
> --Tim Ressel
> Circuit Abbey
> timr at circuitabbey.com
> 
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