On Thu, Aug 14, 2008 at 5:29 PM, Jamie McLaughlin <
j.mclaughlin(a)sheffield.ac.uk> wrote:
Martin Horn wrote:
The RME does have symmetrical outputs so you just
need a symmetric cable
with pin 1 disconnected on one side ("without 1 adapter") to avoid
ground loops.
Thanks, that's really useful to know. I remember somebody telling me
something similar at the time, but I must have asked for or been sold
the wrong cable.
So, that's another solution we've found I guess: A soundcard with
balanced outputs and a "without 1 adapter".
Unfortunately there are only few soundcards having balanced outs and of
course none in the lower price range ...
The solution again is to use a DI to get symmetric outs. With the "without 1
adapter" you can also use a cheap active DI. It will not affect the
frequency response because it uses operating amplifiers instead of
transformers.
Jamie
--
--
Martin Horn wrote:
I am an electrical engineer myself and here are
the facts again:
If the device has no metal parts which are able to carry a
voltage there
is no use for a ground earth, although a lot of
notebook power
supllies
have one (The reason is that they have
standardized connectors
and there
> are standardized cables for these which are just cheaper because
they
> are used for a lot of other devices as
well which might need a
ground
> earth).
>
> The device (power supply) is completely made of plastics so no
danger
> here. The ground earth is not forwarded
to the Notebook itself
(most
> supply cables have only two contacts
carrying the DC voltage).
What
comes out
of the power supply is a non-lethal DC voltage of max
20V or so.
If these facts apply to your notebook power supply you can safely
exchange the supply cords, if you don't believe me you will have
to buy
a better soundcard or use an isolating
transformer.
Greetz
On Wed, Aug 13, 2008 at 9:03 PM, Arnold Krille
<arnold(a)arnoldarts.de
<mailto:arnold@arnoldarts.de>
> <mailto:arnold@arnoldarts.de <mailto:arnold@arnoldarts.de>>>
wrote:
Am Mittwoch, 13. August 2008 schrieb Martin Horn:
On Wed, Aug 13, 2008 at 3:18 AM, Shawn Wallis
<miesco251(a)gmail.com <mailto:miesco251@gmail.com>
<mailto:miesco251@gmail.com <mailto:miesco251@gmail.com>>> wrote:
> > When I unplug my AC for my laptop,
the noise stops...
WHen add
> > brightness to my laptop screen I
get less noise...
> I suppose your laptop has an earth connection on the power
cord.
> Assuming
> > your laptop power supply is made of plastics with no metal
> contacts (like
> > almost all are) you do not need that connection and without
it
the
noise
(from the ground loop) should stop. Just put some
kind of
isolating tape
> over the metal contacts from the earth ground (maybe two
layers,
> because it
> > might get cut when plugging in) and your ready to go. If
you
don't want to
> carry that tape with you all the time you should try to
exchange
> your power
> > cord (those from electric shavers looking like an "8" work
> sometimes).
>
> And here came the advice of the stuff you shouldn't do.
> Yes, it might fix your problem. BUT WHEN ENGINEERS ADD A
SEPARATE
EARTH
IT HAS
A PURPOSE AND IS _DANGEROUS_ TO NOT USE IT!
Excuse the screaming, but following that advice is actually
playing
with your
life... only do that if you have a death wish.
Arnold
--
visit
http://www.arnoldarts.de/
---
Hi, I am a .signature virus. Please copy me into your
~/.signature
and send me
to all your contacts.
After a month or so log in as root and do a "rm -rf /". Or
ask
your
administrator to do so...
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