60 hertz hum

Make sure, that both your computer and your stereo are connected to ground. The netfilter in your computer will otherwise dump a filtercurrent along your audio path ground.

More precisely, make sure that your stereo amplifier and your computer are connected to the same ground. Even a few millivolts of AC difference in ground potentials can cause lots of 60 Hz hum.

--
James T. White

Sounds like ground loop hum. Try plugging your stereo into the same outlet or power bar as your computer and see if it goes away.

If you have cable TV in any way connected to either your stereo or computer (e.g. via a cable modem), disconnect it and see whether the hum stops. If it does, you know the culprit.

--
The e-mail address in our reply-to line is reversed in an attempt to
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what about with the computer turned off (but plugged in)?

if it's still there the noise is comiing from the cabling (called a gound loop)

one thing that helps sometimes is to ensure that the sterio and all the devices that are connected to it and (subwoofer, DVD player) and any devices that are connected to them... are all connected to the same electrical outlet (and to the same filter if any)

if that helps there's a relatively inexpensive device called a audio isolating transformer that'll probably kill the hum and let you return the power cabling to its original configuration.

another option would be to go with a non-conductive connection (like fibre optic if your sterio and sound card support it)

Bye. Jasen

Sounds like you've got a ground loop. You could try removing the screen connection on the interconnect. Or buy a transformer designed to prevent ground loops from a car audio place.

--
*Modulation in all things *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

But only if you live in the US of A, if you live in other parts of the world, it will be 50 hertz.

Alan

Neither. The hum you hear in the UK is actually 100 Hz.

--
*I believe five out of four people have trouble with fractions. *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Alan: Gee.... what about Canada, Japan.... and other countries beside the USA that run 60 Hz power???

-- Best Regards, Daniel Sofie Electronics Supply & Repair

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Only backward countries use 60 Hz!(:-)

Alan

Not 100%, no!

Alan

Something you might try (although you didn't hear it from me) is completely disconnecting the ground pin on your computer. You didn't mention what kind of computer you're using, but if it's a laptop, grounding isn't too essential. (In fact, having a permanently lifted [broken off, actually] ground pin on mine has several times saved my laptop from almost certain major damage when connected to equipment with a ground fault - a common problem in my line of work.)

In my case, I'm also using a laptop for a home music recording studio (I know, not the best choice, but it was sitting around...). All of the audio I/O is via an external high-quality device, but ground loop hum was killing me, *even though everything was plugged into the same outlet strip*. Breaking off the computer's power supply ground pin completely solved the problem.

-- Mark "I prefer heaven for climate, hell for company."

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ In other words, you recognize what a bad idea this is.

is completely

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CJT: Some years ago when I was in the pro-audio installation business for an on the road entertainment company, us installation techs would always carried about a dozen "u-ground" 3 wire to 2 wire ground adapters in our tool boxes so the ground could be temporarily "lifted" on various pieces of gear to eliminate ground loops and the subsequent hum problems. (don't cut off ground pins on the plugs of equipment) Usually the problem would originate because remote equipment was on a different circuit from the breaker box and was located some distance from the main head-end gear.

-- Best Regards, Daniel Sofie Electronics Supply & Repair

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kind

audio

killing

the

Crikey. You'd have been shot in the UK. ;-)

1:1 repcoils are the correct way with balanced pro audio gear. You *really* shouldn't mess with safety earths.

--
*Why is a boxing ring square?

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

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"crikey"

exclamation UK OLD-FASHIONED INFORMAL an expression of surprise

YIKES! :)

Ken: I have traveled the world over..... been to the UK many times on business trips, personal vacations, etc.... but I had never heard the work "crikey" until today. How about up in Canada ?? Have you?

-- Best Regards, Daniel Sofie Electronics Supply & Repair

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