Yeah, this has been covered here before. Look up "DSP loops" in the archives. In short, you can't ask a subpatch/abstraction/whatever to compute output based on it's input simultaneously. Unlike analog electronics, where electrons move almost simultaneously, in DSP it's logically impossible. So your feedback loop must contain a one block delay. [send] and [receive] do that.
However, if your problems are with something like a delay line or filter inside [blackbox~] saturating and "blowing up", then you might look at some kind of limiter, waveshaper or clipper to keep the incoming audio within certain limits. HTH, d. Damian Stewart wrote: > 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 > -- derek holzer ::: http://www.umatic.nl ::: http://blog.myspace.com/macumbista ---Oblique Strategy # 110: "Lowest common denominator" _______________________________________________ [email protected] mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
