Problems with sound balance

[chris]

Hi!

We have just bought two AudioInjector boards for Raspberry Pi, and have set them up using the setup scripts on this forum. Both are working nicely!

Although, we are having a couple of problems:

the line out, the left channel is higher volume than the right
the line in, the left channel is higher volume than the right.

For now we are okay with the line out problem, it's easy to tweak the gain for individual L+R channels in alsamixer, but this cannot be done for the line out, only the headphone output.

Any ideas on how to sort this out?

I think it's a kernel driver or settings issue , since we have a Wolfson Mico board with the same codec I prototyped myself which replicates this problem.

[bklebke]

Just writing to confirm the issue -- I tried a bunch of different mono recordings going into both right and left -- even switched plug order to control for something with the cable or source file. Not a huge, huge deal this moment but definitely something worth fixing at some point

EDIT: interestingly, mine's louder on right than left on line in.

[flatmax]

I can look into this. Can you both please post recordings so I can get an idea of the difference ?

thanks

Matt

[ahihi]

Hello,

I'm seeing this problem as well. Here is a recording from the line output: http://omino.foldplop.com/~ahihi/audioi ... ineout.wav

From a quick glance at Audacity's meters, the left channel is about 5dB louder.

Edit: And it seems the line input has the opposite balance. No wonder I didn't notice this when testing a simple input-to-output pipe.

[flatmax]

Thanks for the follow up.
I can see that the difference is there ... I will start looking into this.

For now ... the difference is correctable by changing the mixer settings.
Nice music by the way

Matt

[flatmax]

I have found the problem with sound balance and have fixed it in the github linux branch - also created a pull request :
https://github.com/raspberrypi/linux/pull/1727

Once this patch gets accepted, L&R channels will have the same volume.

thanks for pointing out the problem.
Matt

[ahihi]

Thank you! I have upgraded to 4.4.35 and can confirm that the balance is now right.

Nice music by the way :)

Cheers, it is from my album. :)