<div dir="ltr"><br><br><div class="gmail_quote">On Thu, Aug 14, 2008 at 5:29 PM, Jamie McLaughlin <span dir="ltr"><<a href="mailto:j.mclaughlin@sheffield.ac.uk">j.mclaughlin@sheffield.ac.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Martin Horn wrote:<br>
<br>
> The RME does have symmetrical outputs so you just need a symmetric cable<br>
> with pin 1 disconnected on one side ("without 1 adapter") to avoid<br>
> ground loops.<br>
<br>
Thanks, that's really useful to know. I remember somebody telling me<br>
something similar at the time, but I must have asked for or been sold<br>
the wrong cable.<br>
<br>
So, that's another solution we've found I guess: A soundcard with<br>
balanced outputs and a "without 1 adapter".</blockquote><div><br>Unfortunately there are only few soundcards having balanced outs and of course none in the lower price range ...<br><br>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. <br>
<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>
<br>
Jamie<br>
<br>
--<br>
<br>
><br>
> --<br>
><br>
> Martin Horn wrote:<br>
> > I am an electrical engineer myself and here are the facts again:<br>
> ><br>
> > If the device has no metal parts which are able to carry a<br>
> voltage there<br>
> > is no use for a ground earth, although a lot of notebook power<br>
> supllies<br>
> > have one (The reason is that they have standardized connectors<br>
> and there<br>
> > are standardized cables for these which are just cheaper because they<br>
> > are used for a lot of other devices as well which might need a ground<br>
> > earth).<br>
> ><br>
> > The device (power supply) is completely made of plastics so no danger<br>
> > here. The ground earth is not forwarded to the Notebook itself (most<br>
> > supply cables have only two contacts carrying the DC voltage). What<br>
> > comes out of the power supply is a non-lethal DC voltage of max<br>
> 20V or so.<br>
> ><br>
> > If these facts apply to your notebook power supply you can safely<br>
> > exchange the supply cords, if you don't believe me you will have<br>
> to buy<br>
> > a better soundcard or use an isolating transformer.<br>
> ><br>
> > Greetz<br>
> ><br>
> ><br>
> > On Wed, Aug 13, 2008 at 9:03 PM, Arnold Krille<br>
> <<a href="mailto:arnold@arnoldarts.de">arnold@arnoldarts.de</a> <mailto:<a href="mailto:arnold@arnoldarts.de">arnold@arnoldarts.de</a>><br>
> > <mailto:<a href="mailto:arnold@arnoldarts.de">arnold@arnoldarts.de</a> <mailto:<a href="mailto:arnold@arnoldarts.de">arnold@arnoldarts.de</a>>>> wrote:<br>
> ><br>
> > Am Mittwoch, 13. August 2008 schrieb Martin Horn:<br>
> > > On Wed, Aug 13, 2008 at 3:18 AM, Shawn Wallis<br>
> > <<a href="mailto:miesco251@gmail.com">miesco251@gmail.com</a> <mailto:<a href="mailto:miesco251@gmail.com">miesco251@gmail.com</a>><br>
> <mailto:<a href="mailto:miesco251@gmail.com">miesco251@gmail.com</a> <mailto:<a href="mailto:miesco251@gmail.com">miesco251@gmail.com</a>>>> wrote:<br>
> > > > When I unplug my AC for my laptop, the noise stops...<br>
> WHen add<br>
> > > > brightness to my laptop screen I get less noise...<br>
> > > I suppose your laptop has an earth connection on the power<br>
> cord.<br>
> > Assuming<br>
> > > your laptop power supply is made of plastics with no metal<br>
> > contacts (like<br>
> > > almost all are) you do not need that connection and without it<br>
> > the noise<br>
> > > (from the ground loop) should stop. Just put some kind of<br>
> > isolating tape<br>
> > > over the metal contacts from the earth ground (maybe two<br>
> layers,<br>
> > because it<br>
> > > might get cut when plugging in) and your ready to go. If you<br>
> > don't want to<br>
> > > carry that tape with you all the time you should try to<br>
> exchange<br>
> > your power<br>
> > > cord (those from electric shavers looking like an "8" work<br>
> > sometimes).<br>
> ><br>
> > And here came the advice of the stuff you shouldn't do.<br>
> > Yes, it might fix your problem. BUT WHEN ENGINEERS ADD A SEPARATE<br>
> > EARTH IT HAS<br>
> > A PURPOSE AND IS _DANGEROUS_ TO NOT USE IT!<br>
> > Excuse the screaming, but following that advice is actually<br>
> playing<br>
> > with your<br>
> > life... only do that if you have a death wish.<br>
> ><br>
> > Arnold<br>
> > --<br>
> > visit <a href="http://www.arnoldarts.de/" target="_blank">http://www.arnoldarts.de/</a><br>
> > ---<br>
> > Hi, I am a .signature virus. Please copy me into your<br>
> ~/.signature<br>
> > and send me<br>
> > to all your contacts.<br>
> > After a month or so log in as root and do a "rm -rf /". Or<br>
> ask your<br>
> > administrator to do so...<br>
> ><br>
> > _______________________________________________<br>
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> ><br>
> ><br>
> ><br>
> ><br>
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</blockquote></div><br></div>