18 Apr
2003
18 Apr
'03
9:46 p.m.
i think you're out of luck...the point of laptop architecture is to squish
everything together....with a monitor and usb (which is fairly high voltage)
so close to an integrated audio card, you cannot avoid magnetic influence as
shielding at this level is practically impossible....you're best bet (and
not a very good solution) is to get a breakout box so the actual dac is
physically outside the laptop. If you come up with better solution please
let me know,its a problem that frequently drives me nuts
From: Ben Saylor <bsaylor(a)Macalester.edu>
Reply-To: linux-audio-user(a)music.columbia.edu
To: linux-audio-user(a)music.columbia.edu
Subject: [linux-audio-user] hum from laptop soundcard
Date: Fri, 18 Apr 2003 13:57:06 +0200
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Hi,
I have a new Dell laptop with a headphone jack as the only external
audio output. With headphones, the sound quality is good and there is
little noise to be heard. However, if I plug in my monitors, the
output crackles and hums, regardless of the mixer levels. There is
217 hz constant hum, a 125 hz hum when moving windows, and a 689 hz
whine when I run Pd. The output crackles when I move the mouse
(external USB). I just noticed that it goes away when I unplug the AC
adaptor. I think I remember a similar problem coming up on this list
before, but I had no luck searching the archives. How can I solve
this?
Thanks,
Ben
_________________________________________________________________
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18 Apr
18 Apr
10:10 p.m.
New subject: [linux-audio-user] hum from laptop soundcard
I use the quattro with my laptop and its very quiet.
http://www.brianredfern.org
On Fri, 18 Apr 2003, alex dray wrote:
i think you're out of luck...the point of laptop
architecture is to squish
everything together....with a monitor and usb (which is fairly high voltage)
so close to an integrated audio card, you cannot avoid magnetic influence as
shielding at this level is practically impossible....you're best bet (and
not a very good solution) is to get a breakout box so the actual dac is
physically outside the laptop. If you come up with better solution please
let me know,its a problem that frequently drives me nuts
From: Ben Saylor <bsaylor(a)Macalester.edu>
Reply-To: linux-audio-user(a)music.columbia.edu
To: linux-audio-user(a)music.columbia.edu
Subject: [linux-audio-user] hum from laptop soundcard
Date: Fri, 18 Apr 2003 13:57:06 +0200
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FILETIME=[AE502DA0:01C305DC]
Hi,
I have a new Dell laptop with a headphone jack as the only external
audio output. With headphones, the sound quality is good and there is
little noise to be heard. However, if I plug in my monitors, the
output crackles and hums, regardless of the mixer levels. There is
217 hz constant hum, a 125 hz hum when moving windows, and a 689 hz
whine when I run Pd. The output crackles when I move the mouse
(external USB). I just noticed that it goes away when I unplug the AC
adaptor. I think I remember a similar problem coming up on this list
before, but I had no luck searching the archives. How can I solve
this?
Thanks,
Ben
_________________________________________________________________
MSN 8 with e-mail virus protection service: 2 months FREE*
http://join.msn.com/?page=features/virus
19 Apr
19 Apr
8:43 a.m.
New subject: [linux-audio-user] hum from laptop soundcard
Hallo,
alex dray hat gesagt: // alex dray wrote:
i think you're out of luck...the point of laptop
architecture is to squish
everything together....with a monitor and usb (which is fairly high
voltage) so close to an integrated audio card, you cannot avoid magnetic
influence as shielding at this level is practically impossible....you're
best bet (and not a very good solution) is to get a breakout box so the
actual dac is physically outside the laptop. If you come up with better
solution please let me know,its a problem that frequently drives me nuts
An external box won't necessarily help, because it will not break the
ground loop, that is happening here. I have the same humming with a
Quattro. There is only one solution: breaking up the ground loop.
First one should try to disconnect everything that is connected to the
amplifier except of course the laptop. I had my main PC connected to
the same amp as my laptop and as soon as I disconnected the first, the
loop was gone.
If this doesn't help, then there is a ground loop between the amp an
the laptop itself. Then you need to break the earth connection between
the laptop and the amp (which is useless anyway) by using for example
a direct input box with ground lift or the Monacor FGA-40 filter.
One can also try to cut the earth of the laptop's powers supply if
one has a death wish... ;) I mean, don't do that.
I collect GroundLoop links on my Wiki:
http://footils.org/cgi-bin/cms/pydiddy/GroundLoop
ciao
--
Frank Barknecht _ ______footils.org__
21 Apr
21 Apr
2:31 p.m.
New subject: [linux-audio-user] hum from laptop soundcard
On Sat, Apr 19, 2003 at 12:33:25PM +0200, Frank Barknecht wrote:
One can also try to cut the earth of the laptop's
powers supply if
one has a death wish... ;) I mean, don't do that.
I have the same buzz problem on my laptop...
i wouldn't physically cut the prong, but I have used one of those
little 2-prong to 3-prong adapters - common in the US, you can find them
in any hardware store here, i assume there's an equivalent elsewhere.
You probably know the type - about 1 inch square, it's got a standard US
3-prong outlet on one side and a 2-prong plug on the other,
with a little tab that you're meant to screw into the center screw of
the wall outlet.
If you ensure that the tab doesn't contact anything grounded,
voila, ground is broken.
is this a safety hazard? I'm not really sure.
Be careful.
A better option would be an AC isolation transformer, but those
don't seem to be easy to find in a packaged, ready-to-use form.
--
Paul Winkler
http://www.slinkp.com
Look! Up in the sky! It's THE LAST SECRETARY-CHUCKER!
(random hero from isometric.spaceninja.com)
22 Apr
22 Apr
7:29 a.m.
New subject: [linux-audio-user] hum from laptop soundcard
Hallo,
Paul Winkler hat gesagt: // Paul Winkler wrote:
On Sat, Apr 19, 2003 at 12:33:25PM +0200, Frank
Barknecht wrote:
Actually I'm also not sure, if it must be a safety hazard. I read
about this solution and I also asked Acer, if they could provide a
2-prong plugged cable for their laptops. They wrote me, that in
Germany they are not allowed to supply such a cable for their laptops,
but I could try to find one somewhere else...
I guess, that the case of a laptop is well isolated from its innards,
and also a lot of cases are plastic, so it seems.
But if it's not isolated, the user would be the ground connection
chosen, and that'll hurt. ;)
Then the epanorama docs say "Do not do this", because it's
"potentially very dangerous":
http://www.epanorama.net/documents/groundloop/problem_solving.html
They call the plug-solution a "cheater plug":
http://www.epanorama.net/documents/groundloop/cheater.gif
ciao
--
Frank Barknecht _ ______footils.org__
One can also try to cut the earth of the
laptop's powers supply if
one has a death wish... ;) I mean, don't do that.
I have the same buzz problem on my laptop...
i wouldn't physically cut the prong, but I have used one of those
little 2-prong to 3-prong adapters - common in the US, you can find them
in any hardware store here, i assume there's an equivalent elsewhere.
You probably know the type - about 1 inch square, it's got a standard US
3-prong outlet on one side and a 2-prong plug on the other,
with a little tab that you're meant to screw into the center screw of
the wall outlet.
If you ensure that the tab doesn't contact anything grounded,
voila, ground is broken.
is this a safety hazard? I'm not really sure.
Be careful. 
8:16 a.m.
New subject: [linux-audio-user] hum from laptop soundcard
On Tue, 22 Apr 2003 11:19:21 +0200, Frank Barknecht wrote / a écrit:
But if it's not isolated, the user would be the
ground connection
chosen, and that'll hurt. ;)
In France, usually laptops cable are not grounded. The Toshiba I'm using for writing
this has an external power supply with no ground.
We have 220V-60Hz ac.
I hope it helps and that it won't hurt!!
Guy CLO~
-----------------------------------------------
#ICQ 37736372
#219055 http://counter.li.org
-----------------------------------------------
http://perso.wanadoo.fr/guy.clotilde/index.html
-----------------------------------------------
12:43 p.m.
New subject: [linux-audio-user] hum from laptop soundcard
On Tue, Apr 22, 2003 at 11:19:21AM +0200, Frank Barknecht wrote:
Then the epanorama docs say "Do not do
this", because it's
"potentially very dangerous":
http://www.epanorama.net/documents/groundloop/problem_solving.html
nice link,thanks!
btw, for anyone considering the Radio Shack car audio isolation
transformer - based on the specs, I'd say don't bother.
Frequency Response:...............300 Hz to 4000 Hz +/- 3 dB
http://support.radioshack.com/support_auto/doc9/9542.htm
OTOH, the Ebtech Hum Eliminator looks like a contendor...
2 channels of quality audio isolation for about $60 US retail.
it is reputed (on rec.audio.pro) to saturate easily at low
frequencies, but good enough to be useful.
then whirlwind has a gadget tailor-made for the laptop audio crowd...
the pcDI - AFAICT it's their Direct2 dual-DI box with an added
stereo 1/8" input and a flashier color box.
supposedly these are quite nice. but pricier - $115 US or so.
--
Paul Winkler
http://www.slinkp.com
Look! Up in the sky! It's KING TELEVISION!
(random hero from isometric.spaceninja.com)
12:57 p.m.
New subject: [linux-audio-user] hum from laptop soundcard
then whirlwind has a gadget tailor-made for the laptop audio crowd...
the pcDI - AFAICT it's their Direct2 dual-DI box with an added
stereo 1/8" input and a flashier color box.
supposedly these are quite nice. but pricier - $115 US or so.
that's only 460 bucks to get all the channels from my Hammerfall card
hum-free. what a bargain! :-)
Derek
7915
days inactive
7919
days old
linux-audio-user@lists.linuxaudio.org
7 comments
6 participants
participants (6)
-
alex dray -
Brian Redfern -
derek holzer -
Frank Barknecht -
Guy Clotilde -
Paul Winkler