Comment 33 for bug 1721987

I was still having problems with my Lenovo Legion laptop, this is one of the pages where I stopped in and tried everything on it, to no avail. It looks like the specific issue here was fixed, and any other info I found on the internet was not working either.

Turns out that by default, headphone jack had right channel turned all the way down! Here's what I did to fix:

Open terminal window. Execute command: sudo alsamixer
This is a terminal-based application that allows you to change audio output levels for different ports. You may need to press F6 to select your sound card -- mine was selected when I started the application. Basically Master and PCM all had both left and right channels maxed into the red zone. Headphones ONLY had the left channel. Press the right-arrow on your keyboard to go over to Headphones, then press the up-arrow repeatedly and the right channel level should increase, take it to the max with the left channel. Exit Alsa Mixer with the escape key.

This fixed it but then the audio in the right channel, for whatever reason, was extremely quiet. I went into Ubuntu's basic sound settings window (Settings > Sound). I made sure I had the "Headphones - Built-in Audio" selected in the dropdown box for Output, then drug the balance slider all the way to the left and let go of mouse button. Then all the way to the right and let go of mouse button. Then back to the middle and let go of the mouse button.

Now it was working and sounded great! I went back into alsamixer one more time, and noticed the right channel on the headphones had dropped a tiny notch compared to the left. I put it back to max, and exited Alsa Mixer.

I now have no problems with my headset! If you're still struggling even though this bug fix was released a year ago, try my simple suggestion before you go all crazy editing files. It might save you many hours of internal screaming :)