[AudioI] Microphone connector gain?

[Ron Patton]

Hi,

I am using the AudioInjector Zero in a hardware project (an Amateur
radio transceiver).   The Zero is working well for audio output.
However the microphone input of the Zero does not appear to have the
gain needed for using a standard run of the mill computer headset.
Now, I'm not an audio expert by any means so some of the following might
not be correct (or actually stupid). But,  my assumption is a standard
computer headset uses an electret microphone element.  These need a
"bias" voltage to operate properly.   I have measured the voltage at the
Zero microphone connection and it is supplying ~2.5V which should be
sufficient.  OK, so far so good.   However, the Zero does not seem to
provide enough gain and the audio volume is a bit low.

There are two things I have done to examine the issue.

1) Attached is the ALSA configure used to configure the Zero.  It is the
file supplied when installing the test routines supplied by
AudioInjector.  It is attached to this email.  It is applied before
starting the application that uses the Zero (via Portaudio).

2) I have used ALSAMIXER to adjust the values that it displays (Mic
Boost and Capture).  These have been set to 100.  (Screen capture attached).

So, the question is:  Is there something I can configure in ALSA (in the
attached asound.state.MIC.thru.test file) or otherwise to raise the gain
of the microphone connection?

-- 
73,
Ron / W4MMP

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