External speaker buzz when charger is plugged in.

Discussion in 'MacBook Pro' started by Forest91, Apr 19, 2009.

  1. Forest91 macrumors member

    Mar 31, 2009
    I've noticed a faint buzzing sound through my external speakers when a charger is plugged in to the laptop. Removing the charge kills the noise and makes the sound crystal clear again. Doesn't bother me to much, but as my uni-macbook pro is plugged in most of the time I can see this near constant buzz getting on my nerves a bit in the future. Any ideas, looking back I experienced the same thing with my macbook.

  2. snowmoon macrumors 6502a


    Oct 6, 2005
    Albany, NY
    Does this happen everywhere, or just in specific outlets. Does it happen with the 3 prong ( grounded ) adapter on the power brick or just the 2 prong adapter?
  3. gersty2 macrumors newbie

    May 19, 2010
    i can confirm that using the 3 prong attachment stops the buzzing. i have it plugged in to a strip so maybe plugging it straight to the wall might work too. having a ground on the speaker side of the setup might also work, if you don't have the mac extension cable. thanks for the tip, snowmoon.
  4. m85476585 macrumors 65816

    Feb 26, 2008
    It could be a ground loop. A normal ground loop happens if you have two grounded points in a circuit, for example if the speakers are grounded and the MBP is grounded, which would mean both would have to be using 3-prong cables. But speaker companies are smart enough to avoid this by assuming the computer will be properly grounded, and every other device will tie into the computers ground. If you are using the 3-prong extension cable for your charger, try the 2-prong adapter instead.

    If you are already using the 2-prong adapter, the cause of the buzzing noise would be different. With the 2-prong adapter in the Magsafe, the computer is kept near but not at ground. The speakers should also be kept near ground by their 2-prong power supply. But the two "near" grounds are not the same, so current can still flow, and this may be picked up by the speakers' amplifier and made into the buzzing noise you hear. If this is the case, using the 3-prong Magsafe cord instead of the 2-prong adapter might help.

    For further troubleshooting, also try disconnecting any other devices that might be plugged into the computers or the speakers.

    If none of that works, you might be able to reduce the noise by improving the signal to noise ratio. To do so, turn the volume almost all the way up on the computer, then lower the volume on the speakers until it is at the setting you want. This is instead of setting the computer at a low volume then turning the speakers up louder. You could also try a ground loop isolator like this
    but you will probably need a few adapters, and I don't know if the audio quality will be 100% preserved (ground loop isolators usually use an audio transformer, which is not always perfect). You could also try using the optical out and running it to an external amplifier, or getting some kind of digital (USB, Firewire) sound card.
  5. emilijav macrumors newbie

    Nov 9, 2011
    Ground loop between speakers and charging laptop

    I recently purchased 2 hi-fi tower speakers for my laptop. It is connected to amp through basic speaker cable and there's RCA cable from my laptop 3.5mm audio to amp input.

    Strange thing happens when I connect RCA jack to my laptop - when laptop is charging, it sends constant buzzing distortion, I assume its ground loop. When I pull out the charger and laptop is working on its battery, it gives clear sound to the speakers.

    Another thing to mention, I have tried connecting RCA jack from amp to my 4in1 CD/LP/tape/radio player and even though it is powered from the power socket there were no buzzing sound.

    There are couple socket outlets I'm using at the corner of my room to connect most electric appliances such as printers, monitor, etc. Amp is connected to one of such outlets. I tried connecting laptop plug to the same outlet as well as directly to all wall sockets testing if anything changes, but noise still presist.

    I have no idea what else to do. Can anyone please advice on this matter?
  6. whitewater2 macrumors newbie

    Jun 24, 2011
    same issue. only fix is three prong plug

    I have a mid-2010 Macbook Pro and until finding this thread, really didn't know what was causing it. As soon as I put the three prong extension on my plug the buzzing went away.

    I tried different outlets before that; same thing. Very odd. But glad I got it resolved.
  7. Böhme417 macrumors 6502

    Mar 11, 2009
    I have searching abounding trying to find a fix. My MBP is always charging with the three prong cable. I still get the buzzing sound. The only way I can seem to fix it (an inconvenience) is to unplug the MagSafe, wait a second or two for the buzzing to stop, and plug it back in. It's inconvenient, because that usually means I'll have to open the lid to keep it from going to sleep when I unplug it. I don't understand. If I can plug the charger back in and it will work without the noise, why does it do it the first time?:confused:
  8. m85476585 macrumors 65816

    Feb 26, 2008
    You could try a 2-prong plug if it's available where you are, or try a different Magsafe. It could be that a circuit somewhere in the Magsafe, the computer, or the speakers starts to oscillate sometimes, but it is reset when you unplug the Magsafe and plug it back in. You might not be able to fix this issue without replacing the Magsafe, the computer, and/or the speakers. It might be difficult to try to convince Apple to fix the issue under warranty, especially if they can't reproduce it, and their attempt to fix it might not fix it.

    Using the optical output would be a good but potentially expensive solution.

    You could try an audio isolator like this:
    But it might not have any effect, and it might slightly reduce sound quality.
  9. nousername57 macrumors newbie

    Sep 5, 2016
    Try using bluetooth speakers, or if you don't have any use a bluetooth wireless audio receiver. I purchased one for $50.00 from jaycar. Australia. This was a perfect fix, no noise whatsoever. Good Luck.

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