USB Mic Dongle Audio Levels

[G8GKQ]

I have been doing some work on audio levels from the USB Microphone dongle for the Portsdown which also applies to the Langstone.

You can adjust the audio level easily by using alsamixer from an ssh terminal. Once you have alsamixer running, press F6 and then select the USB Audio Device. Then press tab to select Capture. The Mic gain in dB is displayed in the top left and the percentage under the histogram. You can dynamically adjust the gain using the up and down arrow keys to set the right level for your Mic. Note the dB setting that you want.

The setting should get saved when you shutdown, but if it does not get saved, you can reset it with the command

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amixer -c 1 -- sset Mic Capture -12dB

Where the dB setting is in the range -12 to 33. It is set in 1.5 dB steps. You can force this to be saved by the command

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sudo alsactl store

The configuration file (owned by root) is at /var/lib/alsa/asound.state.

Dave, G8GKQ

[G8GKQ]

Colin has just pointed out that the script Langstone/run sets the audio levels when Langstone is started up:

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	sudo amixer -c1 cset numid=6 100%  > /dev/null 2>&1
	sudo amixer -c1 cset numid=8 50%  > /dev/null 2>&1

So, if you want the changes to be permanent for Langstone, you would need to edit the "numid=8" line of this script (which uses the percentage value displayed under the histogram on alsamixer).

Dave, G8GKQ