MBP 2018 15 10.13.6 (running this system to use some older software)
About 5 days ago this Mac started producing serious sound errors with any wired output I have available currently (internal speakers or 2 different wired headphones). It does not happen on bluetooth.
If I play a file with sound locally (QT/iTunes/VLC – doesn't matter) or say browse to youtube and play a video there everything is fine, up until I get to the 50 minute mark.
And then all hell breaks loose. Buzzing, clicking every 3-5 seconds, sometimes accompanied by a disturbing warping of sound which is hard to describe but maybe like an echo or modulation effect.
Closing the file if local, or the browser tab and restarting the media offers a temporary fix for another 50 minutes.
This particular issue appeared about 5 days ago, after I installed GarageBand 10.3.4. At that time I also moved a couple of things I use regularly to startup items (Macs Fan Control and Tiny Alarm).
Naturally I strongly suspected the GarageBand install was the culprit, that it had installed some new sound drivers or changed some sound preferences somewhere. The installer for GB (list files) doesn't seem to indicate this though. It has put some things in /Libary/Audio/Apple Loops. Everything else appears to be in Applications or my home folder.
I should point out Garageband does not need to have been launched for this sound problem to appear.
What I've tried so far:
NVRAM reset: doesn't work
The 2 kinds of SMC reset: do not work
Trashing com.apple.audio.SystemSettings.plist and com.apple.audio.DeviceSettings.plist: doesn't work
sudo launchctl kickstart -kp system/com.apple.audio.coreaudiod: It's not clear whether this has any more of a significant effect than stopping whatever media is playing, closing it and reopening it and playing (Or starting a new window/tab with youtube). So doesn't work basically.
Tried deleting various system caches with Onyx and restarting. Did not work.
Opening Audio MIDI set up and playing around with whatever settings are available. Did not work
Booting into a virtually virgin user account: Problem is the same there.
Disabling/removing Macs Fan Control from entire system, not starting Tiny Alarm. Did not work.
Safe mode: safe mode has no audio so I can't do much there, although assume sound drivers could be loaded manually.
Console logs are not particularly informative, if I filter for audio and wait for the sound to go bad, there isn't anything obvious, anything at all. No red dots. 1 yellow dot for Quicktime I noticed.
So far I haven't tried:
Booting into recovery and running disk utility/first aid. (Disk utility when booted into the system reports no errors). I haven't done this yet because I want to do a full back up first, and that takes a long time.
Booting into an entirely different system. I guess I could try that. I have a backup done before the sound went bad I could try and see if the sound problem exists there.
But if anyone has any other ideas I would love to hear them because I'm running out of them.