[AudioI] Microphone connector gain?

[Matt]

Good news, hope that was the problem !

On 5/1/21 5:29 am, Ron Patton wrote:
> Hi Matt,
>
> Thanks for the information and verifying that my configuration is
> correct.   I think I may have found the problem and it was in my
> application.  The application has a quasi gain control (it simply
> reduces the microphone volume applied to the Portaudio call back that
> drives the Zero).   The routine was not correctly calculating the volume
> level.   More testing is needed and I will let you know the results.
>
> 73,
> Ron / W4MMP
>
> On 1/3/2021 22:59, Matt wrote:
>> On 4/1/21 4:55 am, Ron Patton wrote:
>>> 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?
>> Hi Ron,
>>
>> It looks like the mixer is set correctly for the microphone. In the
>> playback section, the input mux is set to microphone. The capture is set
>> to microphone. You should have plenty of gain on the mic.
>>
>> The microphone connector is the through hole capacitor looking footprint
>> on the board. It isn't the stereo input connector. I can see that you
>> measured the voltage on the microphone connector and that looks right.
>>
>> There are some tests you can do with alsa mixer. One test I can think of
>> will connect the microphone mixer directly to the analogue output of the
>> audio codec. Enable the "Output Mixer Mic Sidetone Switch" and check
>> that you can hear the microphone on the output of the sound card.
>>
>> Also triple check that the GND and signal lines of the headset
>> microphone are correctly connected.
>>
>> Matt
>>
>>
>>>> --
>>>> 73,
>>>> Ron / W4MMP
>>>>
>>>>
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