Weird Audio Performance - Late 2013/Mid 2014

[wahugg]

Hi Team - I am a little perplexed given my situation and could use some insights from others.

Original Specs - Late 2013, 15in MBP, 2.3, DG, 16gb

Issue - After using an unofficial charger, the MacBook started to experience bad audio quality via the onboard speakers. Both speakers sound tinny and top out quite badly, especially at high volume and in the mid's to treble's. Audio output via the headphone jack or thunderbolt is not effected. There are no other performance/ functionality issues.

What I have done thus far in order -
1) Switched the speakers with a donor Mac - No change in audio quality on the original Mac. The original Mac speakers functioned normally (no tinny/ topping out) in donor Mac
2) Swapped motherboard for 661-00679 (Mid 2014, 2.5, DG, 16gb), formatted HDD and clean install of 10.15.4 - No change to speakers
3) Changed battery (cycle count over 1000) with a quality replacement from Louis Rossman Group - No change to speakers
4) Changed microphone array with used OEM part - No change to speakers
5) Changed I/O board with used OEM part - No change to speakers

Other Considerations -
- I have run diagnostics and get the all clear code "ADP000".
- I have reset the SMC, then PRAM, then SMC again between every hardware change

See why I'm starting to go crazy? Short of the screen, trackpad, WiFi card, SSD, or MagSafe connector, I essentially have a new Mac. Yes, others can discern the tinny audio and it is even more apparent when playing side by side with another Mac - I'm not crazy .

Thus far I have only invest $120 USD into this refresh/ repair (sold the original board at a premium over the replacement) but from here on out, the other components start to add up quickly in value. Yes, the Mac is roughly 7 years old and some might say it's time to pony up for a new Mac. But to me, I do not see the need (it can drive a 4k screen @ 60hz, can render casual games with no problem, has excellent IO, and doesn't show its computing age outside of 4k video renders). I originally imagined a ~$200 USD refresh would be more worthwhile than ~$2500 USD replacement but here I am, still with tinny speakers.

Any ideas of what could be amiss here? I tried to be methodical in replacing my components but it seems that I've failed in my endeavor to fix the issue.

Warm regards,
Wahugg
AKA Wallace

 

[Sanpete]

I suppose you've asked at ifixit too. Given everything you've tried, I'd guess there's a short in the chassis somewhere.

 

[wahugg]

Hi Team,

I thought I would post an update. Since my original post I have:
1) Replaced the MagSafe connector with a used OEM part - No change to speakers
2) Swapped the speakers one more time with a donor computer - No change to speakers and original speakers work okay in the new donor.

To clarify, I have been using an OEM charger since the incident and have hucked to POS 3'rd part adaptor in the bin where it belongs.

At this point I've concluded that there is some short in the Screen, Keyboard, Trackpad, Wifi Card, or SSD as those are the only silicon or part that hasn't been changed at this point. Due to the lack of methodical way in approaching them/ the associated cost, I am going to just put up with the annoying speaker audio when headphones or a line out is not an option.

Warm Regards,
Wahugg
AKA Wallace

 

[30YrsMac]

Although you are usually correct in assuming the thing that was added (bad charger in this case) Is the most likely suspect…
It sounds like you haven’t tried a fresh os. And although it makes no sense.. I’m assuming you’ve tried all the pram etc resets?

That’s amazing that another motherboard was available and didn’t fix it!

 

[30YrsMac]

You have to put your motherboard (and other parts (hard drive) into a donor machine and see if it happens.