[chuck-users] Filter screaming: danger to hearing

Tomasz Kaye's brain tomasz.brain at gmail.com
Sat Nov 28 11:09:24 EST 2009

Hello all. I know that Kassen already posted to the list about (what
seems like) a filter instability problem in certain situations. But
after a conversation with him it seemed that I hadn't conveyed the
full nature of the problem clearly, so in this post will try to do

To recap, here's some code from Kijjaz that demonstrates the problem:

PulseOsc osc => BPF filter => blackhole;
20000 => filter.freq;
0.5 => filter.Q;
for(int i; i < 100; i++)
    <<< "osc: ", osc.last(), " filter: ", filter.last() >>>;
    samp => now;

The value output by the filter keeps rising.

I ran into this problem while i had a similar patch connected to dac
instead of to a blackhole. I was wearing headphones, but i took the
usual precaution of turning my macbook volume to the lowest level
above 0 before running the patch. To my alarm, the resulting screaming
sound came through my headphones at top volume anyway. It turns out
that when set to any of the volume gradations above 0, the screaming
happens at effectively full volume on my macbook.

So the point of this extra post is to emphasise that (at least for mac
users) the filter screaming issue is currently quite dangerous for
hearing/speakers, even if you take (imo) normal sensible precautions
before running a patch.

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