Re: Very quite microphone

[Alex Gendin <ukkeefy%gmail.com@localhost>]

On Tue, Nov 25, 2025 at 02:31:50AM +0000, Kevin Bloom <ktnb%posteo.net@localhost> wrote:
> Hi all,
> 
> I'm having some trouble with a microphone. If I enable the device in
> mixerctl(1) (which is inputs.revlvl) and set all mic levels to the
> max, I can barely hear the recorded audio at max speaker volume. Here are my settings:
> 
> $ mixerctl -av
> outputs.master=120,120 volume delta=3
> outputs.master.mute=off  [ off on ]
> outputs.master2=120,120 volume delta=3
> outputs.master2.mute=off  [ off on ]
> inputs.beep=108,108 volume delta=36
> inputs.reclvl=255,255 volume delta=3
> inputs.reclvl.mute=off  [ off on ]
> record.mic=252,252 volume delta=64
> record.mic2=252,252 volume delta=64
> inputs.reclvl2=0,0 volume delta=64
> outputs.dacsel=DAC00,DAC01  { DAC00 DAC01 }
> record.source=ADC02,ADC03  { ADC02 ADC03 }
> 
> Any ideas what might cause this? This is using a headset jack, not
> the internal mic as the internal one doesn't record anything other
> than beeps and boops.
> 
> More info:
> 
> $ audiocfg list
> 0: [*] audio0 @ hdafg0: Conexant CX20671
>        playback: 16, 2ch, 48000Hz
>        record:   16, 2ch, 48000Hz
>        (PR) slinear_le 16/16, 2ch, { 44100, 48000, 96000 }
>        (PR) slinear_le 20/32, 2ch, { 44100, 48000, 96000 }
>        (PR) slinear_le 24/32, 2ch, { 44100, 48000, 96000 }
>        (  ) ac3 16/16, 2ch, { 44100, 48000, 96000 }
> 1: [ ] audio1 @ hdafg1: Intel product 2805
>        playback: 16, 2ch, 48000Hz
>        record:   16, 2ch, 48000Hz
>        (P-) slinear_le 16/16, 2ch, { 48000 }
>        (P-) slinear_le 16/16, 4ch, { 48000 }
>        (P-) slinear_le 16/16, 6ch, { 48000 }
>        (P-) slinear_le 16/16, 8ch, { 48000 }
>        (PR) slinear_le 16/16, 2ch, 48000-48000Hz
> 
> 
> $ cat /var/run/dmesg.boot
> ...
> hdaudio0 at pci0 dev 27 function 0: HD Audio Controller
> hdaudio0: interrupting at msi1 vec 0
> hdaudio0: HDA ver. 1.0, OSS 4, ISS 4, BSS 0, SDO 1, 64-bit
> hdafg0 at hdaudio0: Conexant CX20671
> hdafg0: DAC00 2ch: Speaker [Built-In]
> hdafg0: DAC01 2ch: HP Out [Jack]
> hdafg0: ADC02 2ch: Mic In [Jack]
> hdafg0: ADC03 2ch: Mic In [Built-In]
> hdafg0: 2ch/2ch 44100Hz 48000Hz 96000Hz PCM16 PCM20 PCM24 AC3
> audio0 at hdafg0: playback, capture, full duplex, independent
> audio0: slinear_le:16 2ch 48000Hz, blk 1920 bytes (10ms) for playback
> audio0: slinear_le:16 2ch 48000Hz, blk 1920 bytes (10ms) for recording
> spkr1 at audio0: PC Speaker (synthesized)
> wsbell at spkr1 not configured
> hdafg1 at hdaudio0: Intel product 2805
> hdafg1: DP00 8ch: Digital Out [Jack]
> hdafg1: DP01 8ch: Digital Out [Jack]
> hdafg1: DP02 8ch: Digital Out [Jack]
> hdafg1: 8ch/0ch 48000Hz PCM16*
> audio1 at hdafg1: playback, capture, full duplex, independent
> audio1: slinear_le:16 2ch 48000Hz, blk 1920 bytes (10ms) for playback
> audio1: slinear_le:16 2ch 48000Hz, blk 1920 bytes (10ms) for recording
> ...
> 

Hi Kevin,

You might want to check voltage levels supplied to microphone jack.
I use 3.5mm male to male TRS extension cable and multimeter to measure voltage.

I have some USB-to-dual-TRS-3.5mm adapters that provide about 3.0V and this
voltage seems too low for mic in my headset.

Another USB adapter has 3.3V and mic works with this audio device.
3.5mm-to-XLR adapter has 6.7V, mic works the best with this setup.

It may depend on your mic too, e.g. voltage requirement.

Regards,
Alex

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