[PD] feedback stability..?

Steffen Leve Poulsen slagmark at worldonline.dk
Wed Sep 17 17:17:54 CEST 2008

Damien you know about deconvolution?

Just record a click or whatever through the system, then in the 
fft-domain reverse the kernel (play it backwards).
Use this to do convolution on your system.
So in that sense your on  the right track with your ascii diagram.

Dont know the theory behind it, but I did some experiments in pd.
It seems quite efficent in som situations.


Damian Stewart skrev:
> hey pd,
> i'm trying to do feed forward in pd. i think i'm tired and not thinking 
> this through...
> so, i have a [blackbox~] that does stuff to the audio. it uses feedback 
> internally and is currently a bit unstable. can i make it more stable by 
> going like this:
> [...]   [r~ fb]
> |       |
> |       [*~ -0.1]
> | ______/
> |/
> [blackbox~]
> |\______
> |       \
> |       [s~ fb]
> |
> [...]
> is there some funky combination of delays i can achieve this? i get the 
> feeling this only works in analog electronics because you can say that on 
> some level everything happens at exactly the same time - the delays 
> inherent in digital systems mean that this doesn't work...
> what alternative DSP techniques are there for damping unstable feedback loops?
> thanks
> d

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