[AudioI] Microphone connector gain?

[Ron Patton]

Hi Folks,

Any takers on this?

73,
Ron / W4MMP

On 1/1/2021 23:07, Ron Patton via People wrote:
> 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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