TSGL: 60 Hz Hum from Laptop?

[edLynn]

Goeff -

You know, it's guess time with a thing like that, and here's my guess.

You are on the right track with the ground, but I believe that the laptop is 
in itself grounded, and by trying to add an additional ground, you are 
picking up more "audio".

Now, think in terms of the individual pieces that you are putting into play 
when you use the laptop in the system. Start with the connecting cable to 
the amp. Is it shielded? If not, it's an excellent source for your hum.

Are you using an "audio output" jack, or a 'no-no'
8 ohm headphone jack on your laptop. That's another good hum source. Is your 
computer within proximity to your system speakers? If so, another piece of 
bad news, but that's usually a feedback noise. The mic input jack   will 
also offer a feedback sound, as well as a live mic near the speakers, or 
amp. Are the speakers the old magnetic type. If so, there is a magnetic 
field which should be avoided.

Disconnect and re-connect one piece at a time

BTW, you do understand that your laptop itself offers plenty of noise with 
the whirring HD. Also, neighboring appliances are also culprits for sound 
emissions.

ED
----- Original Message ----- 
From: "Geoff Glave" <misterclever at hotmail.com>
To: <list at tsgserver.com>
Sent: Sunday, April 06, 2008 4:19 PM
Subject: TSGL: 60 Hz Hum from Laptop?



Hey All,

As part of our entertainment system we've got an old Dell laptop plugged 
into our amplifier.  It's on our wireless home network and we use it to play 
MP3s and listen to 'internet radio.'

However, it's got an annoying problem.  When the power supply is plugged 
into the laptop (i.e. most of the time) you hear an annoying 60-hertz 'hum' 
over both right and left amplified channels.  If you unplug the power supply 
from the back of the laptop, the hum goes away.  I've tried running a ground 
to some of the external metal on the laptop, but instead of the hum getting 
better (as expected) it got worse.

Any suggestions as to how to make our home entertainment system work better? 
How can we get rid of this 60 hertz hum?

Thanks in advance.

Cheers,
Geoff in Vancouver, Canada

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