[linux-audio-user] Volume control with Delta44

toby at tobiah.org toby at tobiah.org
Sun May 25 11:54:01 EDT 2003


> 	2) Despite all of this, the card still doesn't have the volume
> sensitivity it does under Windows.  With Windows, a condenser mic is
> fully as sensitive as it should be.  Under GNU/Linux, it leaves a little
> bit to be desired.
> 

I don't have the answer to why the ADC sliders would zero when
you touch the IPGA sliders.  This doesn't happen for me.  Here,
however is the skinny on the two sets of sliders.

You can think of the ADC sliders as a master input volume that
should usually be all the way up.  If they are less than fully
open, then you will have to make up that gain in your mike
preamps, and introduce more noise.   The IPGA (input gain adjust?)
sliders are a gain control on the input amp, which is a bit
different than a master volume.  In general, you want to turn the
gain on an amp down all the way, and then open it only as much
as you need to to get the needed signal boost, as this is where
you will raise the noise floor.  Having said that, I find that
the IPGA controls an extremely clean amplifier, and may well be
a better place to get as much gain as possible unless you have
very clean mic preamps.  The original philosophy behind this
adjuster was to set either the -10 or +4 dB input standard based
on what your equipment delivered.  Indeed, it makes sense to
send what your equipment calls zero dB to the card, and adjust
the input on the delta accordingly, and then just leave it there.

As for comparison with windows, you will be pleased to learn that
while windows has only the two gain positions, ALSA enables us
to use any IPGA setting, including setttings up into a range that
is far more sensitive than what windows allows, so the flexibility
here lies with ALSA.

Are you using the latest ALSA and envy24control?   As I mentioned,
the behavior of the two sets of sliders affecting each other is
not the normal behavior.

Tobiah




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