25 Jul
2007
25 Jul
'07
5:58 a.m.
Quoting Ken Restivo <ken(a)restivo.org>rg>:
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On Wed, Jul 25, 2007 at 08:55:19AM +0200, Malte Steiner wrote:
The solution for me was to remove or lift the ground pin on the laptop's
power supply.
After a lot of testing and asking questions on lists (including this
one), that was the solution.
That is an extremely dangerous thing to do. Quoting
http://www.epanorama.net/documents/groundloop/problem_solving.html:
"Do not do this. Removing the ground connection isn't right. It is against
electrical safety regulations and potentially very dangerous. Removing
ground connection can defeat the actions of your noise filter or spike
protectors inside the equipments. If the ground connection is cut then a
fault in the isulation inside equipment will cause dangerous voltages to the
equipment case instead of burning a fuse. Removing the ground connection
from the equipments which have it is dangerous, against electronic safety
regulations and you risk damaging your equipment. Running without a power
ground will not automatically electrocute you but will make this much more
propable if something goes wrong in your system."
Sampo
I am still searching for the ultimate solution
for the dreaded laptop
hum and guess the only real one to end it all is to get a RME PCMCIA
Card with Digiface and separate converters connected with optical ADAT,
or?
25 Jul
25 Jul
6:53 a.m.
New subject: Realtek ALC882D
On Wed, Jul 25, 2007 at 10:58:07AM +0300, Sampo Savolainen wrote:
That is an extremely dangerous thing to do.
Absolutely. You risk not only frying yourself but also others,
and immediate damage to any equipment you connect to.
In both cases it will be very clear that you're the one
to blame.
The proper way to solve this is to get the wiring right, or
use another soundcard.
--
FA
Follie! Follie! Delirio vano è questo !
1:15 p.m.
New subject: Realtek ALC882D
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On Wed, Jul 25, 2007 at 10:58:07AM +0300, Sampo Savolainen wrote:
Quoting Ken Restivo <ken(a)restivo.org>rg>:
It's a laptop.
We're talking about 19VDC here. IANAEE, but I imagine that the $20 laptop power supply
will sacrifice its life in case of lightning strike, horrible mains power fault, surge, or
other disaster, leaving both the laptop and the performer intact.
Up until this year, I've never seen a laptop power supply with a ground pin anyway, at
least here in the USA. They've all been two-pin AC, no ground. I've never had any
kind of dangerous problem with them, in nearly over 15 years of using laptops. The
grounding of laptop power supplies is a new thing.
Finally, I always run all my stuff off of a multi-outlet strip with a breaker. That thing
is supposed to give its life as well too.
There is no other solution. I've been told that the buzz/ground problem is *inside*
the laptop and all of them have it. It's a cost-saving and space-saving measure that
the PCB designers make.
I also need to point out that changing audio interfaces did not eliminate or even mitigate
the buzz, and, I'm told could not have done so. I heard the buzz with USB and firewire
interfaces.
I suppose if one is really safety counscious, one could run the laptop off of its battery.
However, running out of battery in the middle of a show, is, um, disconcerting.
:-)
- -ken
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On Wed, Jul 25, 2007 at 08:55:19AM +0200, Malte Steiner wrote:
The solution for me was to remove or lift the ground pin on the laptop's
power supply.
After a lot of testing and asking questions on lists (including this
one), that was the solution.
That is an extremely dangerous thing to do. Quoting
http://www.epanorama.net/documents/groundloop/problem_solving.html:
"Do not do this. Removing the ground connection isn't right. It is against
electrical safety regulations and potentially very dangerous. Removing
ground connection can defeat the actions of your noise filter or spike
protectors inside the equipments. If the ground connection is cut then a
fault in the isulation inside equipment will cause dangerous voltages to the
equipment case instead of burning a fuse. Removing the ground connection
from the equipments which have it is dangerous, against electronic safety
regulations and you risk damaging your equipment. Running without a power
ground will not automatically electrocute you but will make this much more
propable if something goes wrong in your system."
I am still searching for the ultimate solution
for the dreaded laptop
hum and guess the only real one to end it all is to get a RME PCMCIA
Card with Digiface and separate converters connected with optical ADAT,
or?
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1:58 p.m.
New subject: Realtek ALC882D
On 7/25/07, Ken Restivo <ken(a)restivo.org> wrote:
It's a laptop.
We're talking about 19VDC here. IANAEE, but I imagine that the $20 laptop power
supply will sacrifice its life in case of lightning strike, horrible mains power fault,
surge, or other disaster, leaving both the laptop and the performer intact.
Up until this year, I've never seen a laptop power supply with a ground pin anyway,
at least here in the USA. They've all been two-pin AC, no ground. I've never had
any kind of dangerous problem with them, in nearly over 15 years of using laptops. The
grounding of laptop power supplies is a new thing.
It's 19VDC, until someone spills beer on the laptop power supply and
you get 120VAC...
There is no other solution. I've been told that
the buzz/ground problem is *inside* the laptop and all of them have it. It's a
cost-saving and space-saving measure that the PCB designers make.
They certainly don't all have it, and I would return a laptop as
defective if it had this problem. For example I would be very
surprised if a Mac had this issue as they are designed for pro audio
use.
Lee
5:23 p.m.
New subject: Realtek ALC882D
On Wed, 2007-07-25 at 08:15 -0700, Ken Restivo wrote:
It's a laptop.
We're talking about 19VDC here. IANAEE, but I imagine that the $20 laptop power
supply will sacrifice its life in case of lightning strike, horrible mains power fault,
surge, or other disaster, leaving both the laptop and the performer intact.
Don't fool yourself. The power supply uses 115V AC or 230V AC depending
on your area. When a design is meant for grounding, there is usually a
common ground point where everything in the device is connected to. If
you disconnect the ground, a short between any ground point and the
mains voltage will flow to your laptop through the "common" (0V) pin of
your PSU. This will eliminate any buzz from the laptop permanently, but
only after it stops sizzling.
The PSU has been designed to be be grounded, hence the ground pin.
Up until this year, I've never seen a laptop power
supply with a ground pin anyway, at least here in the USA. They've all been two-pin
AC, no ground. I've never had any kind of dangerous problem with them, in nearly over
15 years of using laptops. The grounding of laptop power supplies is a new thing.
Finally, I always run all my stuff off of a multi-outlet strip with a breaker. That thing
is supposed to give its life as well too.
There is no other solution. I've been told that the buzz/ground problem is *inside*
the laptop and all of them have it. It's a cost-saving and space-saving measure that
the PCB designers make.
I'm sorry, but this just is not true. If the "buzz" would be *inside*
the laptop and couldn't be affected by things outside it, how would
removing the earth connection help?
To properly remove the hum, there are a large number of options.
- If you are using balanced connections, you can disconnect the ground
pin on the balanced connection from either side of the cable.
- There are isolation transformers which electrically separates the
input from the output.
- You can separate the ground between the input and output using a very
small resistor and a capacitor in parallel.
I also need to point out that changing audio
interfaces did not eliminate or even mitigate the buzz, and, I'm told could not have
done so. I heard the buzz with USB and firewire interfaces.
Which is natural as the USB or firewire device will be connected to the
same electrical system as the PSU.
Please, for your own sake, fix the hum properly. And for everyone elses
sake please don't recommend removing the ground pin.
Sampo
5:47 p.m.
New subject: Realtek ALC882D
On Wed, Jul 25, 2007 at 10:23:12PM +0300, Sampo Savolainen wrote:
On Wed, 2007-07-25 at 08:15 -0700, Ken Restivo wrote:
Is there any "buzz" when you use the laptop with only passive
external equipment, e.g. a headphone/mic combo, and the ground
connected ? If not then it's not an internal problem.
--
FA
Follie! Follie! Delirio vano è questo !
There is no other solution. I've been told
that the
buzz/ground problem is *inside* the laptop and all
of them have it. It's a cost-saving and space-saving
measure that the PCB designers make.
I'm sorry, but this just is not true. If the "buzz" would be *inside*
the laptop and couldn't be affected by things outside it, how would
removing the earth connection help?
5:49 p.m.
New subject: Realtek ALC882D
On Wed, 2007-07-25 at 22:23 +0300, Sampo Savolainen wrote:
To properly remove the hum, there are a large number
of options.
I forgot the most obvious one. There should not be any ground loop
issues if all the devices you use are connected to a common ground.
Using the same mains distribution box for your audio equipment is a good
solution for home setups.
Sampo
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days inactive
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linux-audio-user@lists.linuxaudio.org
6 comments
4 participants
participants (4)
-
Fons Adriaensen -
Ken Restivo -
Lee Revell -
Sampo Savolainen