3.5mm jack audio humm on Macbook

thestickman

I took my shiny new Macbook, and plugged it into my HiFi using the 3.5mm out the way i always have with computers. It produces a loud humming. The audio plays through as well but it is unlistenable due to this humming.



Now if i whack in some headphones, i can hear the same thing, a bassy humm with white noise over the top, but its fine to listen to as its much quiter than the music. In fact i only hear it when no music is playing.



Whats going on? Does anyone know? Is there anything i can do about this fault/characteristic?





Any help or advice would be much appreciated as using headphones isnt ideal adn i dont really want to shell out for a airport. (and no my hifi doesnt have digital/optical in so i cant use that )

Thanks for your time,

Phil

kickaha

Is there a hum when listening to the MacBook with headphones?



If not, then you have a grounding issue in your hifi system. Try plugging the MacBook into another outlet, or leaving it on battery.

shetline

The audio jack is both electrical analog and optical digital. If you've got a TOSLink input you can use, you'll not only eliminate any chance of ground loop hum, you'll get the best sound out of your MBP that you can get, without even that faint hum you hear on your headphones.



If you have to go with an analog connection, don't want to leave your MBP running on battery, and using a different AC outlet doesn't help, you can always throw in a 1:1 isolation transformer.

chucker

<nitpick> It's an MB, not an MBP. Still has optical though.

thestickman

thanks all, you nailed it. it was an earth loop caused by having my hifi in one side of a twin socket and my MB in the other. So simply but it was driving me nuts.

Thanks again,

Phil

1337_5l4xx0r

You can get cheap powerbars with EMI/RFI filtration... plug your stereo components into one, and you'll get noticeably cleaner audio.