Topic: Microphone gain

Hi - not sure whether this is a hardware or a software question, but when I use the microphone on the Chumby, the audio is recorded way to loudly (it clips like crazy).
I have been trying various ways to use amixer/arecord/etc to control the gain on the mic, without any success.
How does one adjust the gain on Chumby's internal microphone?

Thanks!

Greg Hassett

Re: Microphone gain

I think I answered that one before - in any case, we're adding support for microphone gain in the ALSA driver for the next firmware release.

Re: Microphone gain

Thanks Duane -- I did ask the question before (http://forum.chumby.com/viewtopic.php?pid=12428#p12428) but it didn't get answered until now.

Any idea when the next firmware release will be issued?

Thanks again . . . your help is very much appreciated.

// greg //

Re: Microphone gain

ghassett wrote:

Thanks Duane -- I did ask the question before (http://forum.chumby.com/viewtopic.php?pid=12428#p12428) but it didn't get answered until now.

Hmmm, can you please check your incoming email for April 18th, around 9am PDT?  I provided some technical info that would help you work around this until we get the firmware out.

The next update is in QA - I'm not sure of the release schedule, but my guess is either late May or early June.

Re: Microphone gain

Hi Duane -- I checked my email (both my personal email and the hotmail account that is associated with my profile on the Chumby forums) but did not find any info.

The deleted items folder of my personal email only goes back to April 25, so if it got flagged as junk or accidentally deleted, I may have lost if forever.

I am extremely interested in reading it though -- if you have it handy, could you re-send, please?

Thank you so much . . .

// greg //

Re: Microphone gain

Will do - resent to the hotmail account.

Re: Microphone gain

Duane -- your help was very much appreciated -- Thanks to your help, I can work around the gain issue until the next rev of the firmware!

// greg ///

Re: Microphone gain

Why is this information not published here???

Linux Guy - Occasional Chumby Hacker

Re: Microphone gain

I didn't publish it here because I don't want people to write applications that use it and thus force us to support the absolutely *wrong* way to do it on an ongoing basis.

If you have a specific need, I'll certainly share it with you, but the problem with me posting it is that somebody will stumble across the post a year from now and try to use it.

It's actually easy to figure out - you dig around /proc a bit, and read the data sheet for the TSC2100.

Re: Microphone gain

I was wondering if it was a proc entry.  We have problems with people using debug proc entries for functionality at work too... then somebody thought it would be a good idea to document our driver's proc entries!?!?!! tongue

Linux Guy - Occasional Chumby Hacker

Re: Microphone gain

i am a lucky owner of a chumby one and i love playing with it. i managed to compile and run pjsua as sip phone on it. in order to hear the party on the chumby side better i need to increase the mic gain. using amixer i already raised the microphone level to 100% but the chumby user is still very very silent. if he holds the chumby like a phone in front of his mouth it's finally loud and clear, but i want it to reach the gain level of a hands-free phone (of course) standing on a table.

can you please reveal how to increase the gain of the internal microphone?

regards
Pascal

Re: Microphone gain

Try increasing 'ADC PGA', and to a lesser extent 'Mic PGA':

amixer set 'ADC PGA' 100%
amixer set 'Mic PGA' 50%