25 Jul
2007
25 Jul
'07
1:15 p.m.
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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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