10 Sep
2009
10 Sep
'09
1:02 a.m.
On Wed, Sep 09, 2009 at 10:50:00AM -0400, William Case wrote:
But I do have a question that is mystifying me.
Why is there a volume control for PCM?
Because the mixer itself in the sound card has such a volume control for
PCM. It's either an attenuator or a gain control at the output of the
digital to analog conversion, and before the signal reaches the common
bus where all signals go to before they hit the main volume control.
On some sound cards it is possible to have PCM level set too high,
generating clipping or other noise, which can't be undone by lowering
the main volume control.
Sound cards also vary somewhat ... for some drivers it isn't possible to
choose a PCM level that will work correctly on all cards.
How, or in what order or priority, do you usually the
adjust volume
levels of alsa, application and physical (knob or button on speakers
etc.) controls? So far I just have been twiddleing a little of this or
more of that with no real rationale.
I just play, to see what sounds best.
Another example ... on an emu10k1 here there are bass and treble tone
controls somewhere between the PCM control and the output controls ...
and the bass and treble tone controls can generate some bad sound if the
PCM level is too high. They can be switched out though.
--
James Cameron
http://quozl.linux.org.au/