Hi I'm creating an installation of sorts, using PD to process live sounds from a stereo mic and playing them back with basic effects (delay, reverb, ring modulation), with the speakers mic and laptop all concealed from sight in a very small space. The problem is that after only a couple of minutes all I have is feedback, regardless of the effect I use..

Are there any patches that can prevent/mitigate feedback in a confined space?

Any help or advice would be gratefully received!

Thanks

J

This is possibly due to the "resonance" of the room.

There was an experiment done by some guy who's name i forget where he recorded himself saying "i am sitting in a room".
Then played it back, and recorded the result again.
He continued doing this, and found that after several repeats, all he had left were the resonant frequencies of the room, because they made themselves more prominant.

In this case, i would suggest that you have some form of counter that every one or two minutes, creates a pause in the input or output, long enough to prevent that build up.

if you can figure out what frequencies are feeding back, then you can put a notch filter on those frequencies to avoid the unwanted resonance.

@godinpants said:

This is possibly due to the "resonance" of the room.

There was an experiment done by some guy who's name i forget where he recorded himself saying "i am sitting in a room".
Then played it back, and recorded the result again.
He continued doing this, and found that after several repeats, all he had left were the resonant frequencies of the room, because they made themselves more prominant.

In this case, i would suggest that you have some form of counter that every one or two minutes, creates a pause in the input or output, long enough to prevent that build up.

Alvin Lucier =-)

What you are doing is, by definition, "feedback." The only way to really prevent feedback in a system is by really clever mic/speaker positioning or by not letting it happen all. You could also simply alternate between sample and playback. If you were to find the resonance of the room you could notch out the dominant frequency and it's multiples.

Thanks very much for your help guys.

I used a counter to turn the system off for a while then back on again as well as a couple of filters. The room was actually a lift so the ambient noise was exacerbated by its moving machinery - the filters couldn't cut out feedback altogether but overall managed to achieve the effect I was after.

I wish i could play a gig in a lift.

But its good to see you got everything worked out.
If you have any recordings of what went down you should upload them, I want to hear how this sounded.