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AdriftAtlas

macrumors member
Original poster
Oct 27, 2016
87
72
I've noticed that whenever the laptop is charging via Magsafe 3 or a left TB4 port that there is CPU usage induced static noise through the headphone jack.

It's especially prevalent while scrolling through a webpage and listening to a quiet Facetime call or YouTube video.

The left channel of the headphones is much more affected than the right channel. Likely because the tip is carrying the left channel in a Tip Ring Sleeve (TRS) jack.


Charging the laptop using the right TB4 port or running on battery makes the issue go away.

A 30W charger does not cause noise, while anything 45W or more produces noise likely because it has to use a much higher voltage of 20V.

Optimized Battery Charging sometimes hides the noise by using battery instead of AC power when it's discharging from 100% to 80%.

Has anyone noticed the same? Is this a design issue?
 
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bolognese

macrumors newbie
Aug 9, 2020
15
12
Hey, it's the same for me since day 1 on my 14' MBP M1 Max!
Did you troubleshoot the issue?

I own Audio Technica MSR-7 headphones and the problem is so pronounced, I stopped using them :(
 

AdriftAtlas

macrumors member
Original poster
Oct 27, 2016
87
72
I ended up buying an 80 Ohm impedance adapter. It eliminates the CPU noise and the popping noise when the audio circuit turns on. I don't understand why Apple didn't consider low impedance headphones in their design.

80 Ohm Impedance adapter:

Might also want to get a strain relief:
 
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francescodieci

macrumors newbie
Aug 23, 2022
1
1
I have the same on my brand new 14" M1 Pro, just noticed it because I am a music producer and keeping a DAW open keeps the audio device working so every scrolling makes a hearable noise (like electrical but very low in volume). Read about someone else having the same issue on Reddit and I also confirm it happens on the left side of the machine, both with Magsafe and TB. Charging from the right side makes no noise. Definitely a design flaw by Apple.
 
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Ancandis

macrumors member
Nov 18, 2009
89
25
Hey, it's the same for me since day 1 on my 14' MBP M1 Max!
Did you troubleshoot the issue?

I own Audio Technica MSR-7 headphones and the problem is so pronounced, I stopped using them :(
Does this issue still persist with macOS Ventura?
 

Evan_jumps

macrumors newbie
Oct 17, 2022
2
0
Does this issue still persist with macOS Ventura?
Can confirm it still happens on Ventura.

Anyone found a solution for this besides external hardware? Driving me insane trying to edit videos.

I've noticed it happens themes when scrolling webpages with my magic mouse or moving my timeline around in final cut.

Using a studio display so there's no way to edit on the studio display without cracking and popping.
 

teotuf

macrumors member
Jan 24, 2012
59
6
This is likely a hardware design issue. A parasitic current likely enters the audio circuit from the power circuitry.
Have you tried using the 3 prong power extension cord on the charger? I have a similar issue with hum/buzz while trying to use the mac as a guitar amp and there is a constant buzz/hum that I found out is a ground loop issue as the charger does not ground the laptop unless you use the 3 prong extension cord.
 
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Ancandis

macrumors member
Nov 18, 2009
89
25
Have you tried using the 3 prong power extension cord on the charger? I have a similar issue with hum/buzz while trying to use the mac as a guitar amp and there is a constant buzz/hum that I found out is a ground loop issue as the charger does not ground the laptop unless you use the 3 prong extension cord.
Evan_jumps said that he/she is using an Apple Studio Display. Doesn’t it come with a grounded (3-prong) power cable?

Do you experience the issue on the left side only or also with the right TB port?
 
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