[linux-audio-user] noisy capture->playback

David dplist at free.fr
Sun Nov 2 15:48:58 EST 2003

On 02 Nov 2003 13:32:19 -0600
Jan Depner <eviltwin69 at cableone.net> wrote:

> On Sun, 2003-11-02 at 12:07, David wrote:
> > 
> > Bad noise comes when I set H/W Out 1/2 to PCM Out 1/2 and connect
> > using jackd the alsa capture port (that map to a H/W In) to the alsa
> > playback port 1/2 (that maps to PCM Out 1/2).
> > 
> > Is this a better description ?
> > 
> 	Yes.  I believe Joe is correct - it sounds like a feedback loop
> to me. Why are you connecting these?  If you want to monitor in
> real time just set HW Out 1/2 to Digital Mix L/R.

I wanted to play a guitar through jack-rack and I heard this noise. Did
it come from jack-rack, a ladspa plugin, jackd, alsa, the soundcard ?
This is why I tried to isolate the problem, ending with a very simple
setup : jackd connects the input channel to the output channel PCM Out 1
assigned to H/W Out 1 (with the "PatchBay/Router" in envy24control). I
still get the noise.

I don't have this problem when doing true hardware monitoring of the
input : be it by assigning H/W In 1 to H/W Out 1 (with the
"Pathbay/Router") or by assigning Digital Mixer L to H/W Out 1 (with
the"Patchbay/Router") and unmuting/raising the slider of channel H/W
In 1 with the "Monitor Mixer" pane in envy24control.

> Jan



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