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My late 2020 M1 MacBook Air has picked up a new quirk: audio from both the left and right channel is only coming out of the left side speaker. What's odd about it is that if I play a "stereo test" video, or if I play white noise and slide the Sound Settings balance slider between left and right, then the timbre of the sound changes slightly (but it keeps coming out of the left speaker).

(What I would expect to happen with a failed right speaker is no sound from the right channel, not "right channel comes out the left side"!)

The two main ways I've been testing it are

  • play music or white noise, slide balance slider back and forth in Sound Settings
  • use the "test" buttons on each channel in Audio MIDI Setup

I've used an (imprecise) decibel meter app on my iPhone to make sure that I am not hallucinating. Sound pressure is highest on the left side and falls off consistently as I move away from there, including over the right side speaker. With stereo white noise, there's a ~15dB difference between directly over the left side of my laptop and the right side.

Things I have tried that did not fix it:

  • removing all third-party audio drivers (Zoom, Krisp, etc)
  • upgrading from Monterey to Ventura
  • booting into safe mode to test (but there's no audio in safe mode!)
  • creating a new user and testing audio
  • double-checking Accessibility settings, in case I flubbed something when setting up accessibility settings for my Airpods

I haven't popped the back off yet, although honestly other than checking connectors I'm not sure what I'll do when I do pop it open, because I can't come up with any explanation for both channels coming out of the left speaker, or about the timbre change. I've got all the tiny screwdrivers and spudgers I'd need, though, and I'm comfortable poking around a little.

I've had a hard time putting my finger on what exactly the timbre change is. White noise played through the right channel (still coming out the left side!) feels more distant, which might be that it's just a little quieter, or it might be that it's got less low end, I can't quite tell. But it's definitely different, and panning that white noise from left to right is a linear change, there's no "sweet spot" at centre or anything so I don't think it's a phase issue or something weird like that.

Unfortunately I don't know when it began. I think it was recent, because when I noticed it, it was not subtle. Headphones, both wired and Bluetooth, work fine. I did recently buy and connect a pair of Airpods Pro (2nd gen) but I can't imagine how that would impact anything.

It is no longer under warranty or AppleCare.

Anybody have any idea what might be going on, or what I should try, either when I open it up or in software?

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  • When did this start happening? Did you install any software that would have included any audio components? Please edit your post with this information and any other relevant details that could aid in finding a solution.
    – agarza
    Commented Feb 12, 2023 at 3:12
  • @agarza as I mentioned in the post, I don't know when it began, only that I noticed it a few days ago for the first time. I haven't installed any audio software recently, and I removed all Audio HAL plug-ins that were installed.
    – mendel
    Commented Feb 12, 2023 at 4:47
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    Thoughts: As it doesn't affect wired headphones, software re-mapping seems less likely. I'd be tempted 'just in case' to try contact cleaner on the headset jack - power down & don't spray in the socket on a lappy, you're never sure where it will end up & what is still powered with the machine off. Try spraying the jack plug & jam the plug in & out a couple of dozen times. It is kind of hoping there's just enough 'dribble' off the plug to make sure the switch contacts in the socket are cleaned, without bathing the whole thing in cleaner.
    – Tetsujin
    Commented Feb 12, 2023 at 10:47

1 Answer 1

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I'd forgotten I'd asked this here. I ended up taking it in to a third-party Apple repair shop, where they replaced the audio board to no avail, and did a bunch more testing (because the tech was annoyed by the problem, I think!) including swapping in a new main logic board that they had available which fixed the problem.

I decided that this old MacBook wasn't worth the expense of a mainboard replacement so I've just been putting up with it, but a new mainboard would've fixed it for me.

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