I have a DELL XPS M1530, its new, it cost like $2700. You said dell is a professional vendor... does it sell extra power adapters? > Message: 17 > Date: Thu, 14 Aug 2008 14:46:31 +0200 > From: "Martin Horn" <martin.horn@xxxxxxxxx> > Subject: Re: My Tascam US-122 > To: "Jamie McLaughlin" <j.mclaughlin@xxxxxxxxxxxxxxx> > Cc: linux-audio-user@xxxxxxxxxxxxxxxxxxxx > Message-ID: > <a41657e10808140546i5592d58nac1ef0d6f7789d32@xxxxxxxxxxxxxx> > Content-Type: text/plain; charset="iso-8859-1" > > On Thu, Aug 14, 2008 at 12:08 PM, Jamie McLaughlin < > j.mclaughlin@xxxxxxxxxxxxxxx> wrote: > > > Hi, > > > > I have been advised not to disconnect the earth pin from a laptop in > > these circumstances. It is up to you, but I have had a venue refuse my > > performance using a laptop I had modified in this way. > > > > Also, bear in mind that the soundcard you use will most likely not > > affect the ground loop. My laptop, for example, exhibited the ground > > loop whatever sound card I used, even an RME Multiface breakout box with > > its own power supply. > > > 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. > > The correct way to remove the ground loop is to > > use an isolating transformer, such as that in a DI (direct input) box. > > > Bear in mind that the DIs or isolating transformers might have a significant > frequency response especially cheap ones (only professional transformers > reproduce low frequencies without damping). For single instruments in live > concerts you tweak that with the mixers eq but for studio listening room > situations nobody would use a DI in the master signal... (if not Klark > Teknik or BSS which cost like 120 Euros each, you can almost buy a new > laptop for this ; ) ) > > > > Most venues will have DI boxes, or you can buy your own. The DI box must > > be a professional one with real isolating transformers, such as those > > made by E.M.O. I bought a passive stereo EMO DI box (E525). > > > > http://www.canford.co.uk/Products/20-032.aspx > > > > Of course, the very best thing to do is eventually upgrade to a laptop > > which does not exhibit a ground loop. > > > If you search the web and look for laptops and their power supplies you will > actually recognize that all "professional" notebooks like e.g. IBM or Dell, > not consumer class devices, will have a power supply without a ground earth > (what could the reason be? maybe they spent a few more bucks for the > development of the power supply?). > > I now have a Thinkpad X41, which > > does not have the problem. > > > > Good luck! Ground loops are annoying. > > > > 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@xxxxxxxxxxxxx > > > <mailto:arnold@xxxxxxxxxxxxx>> wrote: > > > > > > Am Mittwoch, 13. August 2008 schrieb Martin Horn: > > > > On Wed, Aug 13, 2008 at 3:18 AM, Shawn Wallis > > > <miesco251@xxxxxxxxx <mailto:miesco251@xxxxxxxxx>> 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... > > > > > > _______________________________________________ > > > Linux-audio-user mailing list > > > Linux-audio-user@xxxxxxxxxxxxxxxxxxxx > > > <mailto:Linux-audio-user@xxxxxxxxxxxxxxxxxxxx> > > > http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user > > > > > > > > > > > > ------------------------------------------------------------------------ > > > > > > _______________________________________________ > > > Linux-audio-user mailing list > > > Linux-audio-user@xxxxxxxxxxxxxxxxxxxx > > > http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user > > _______________________________________________ > > Linux-audio-user mailing list > > Linux-audio-user@xxxxxxxxxxxxxxxxxxxx > > http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: http://lists.linuxaudio.org/pipermail/linux-audio-user/attachments/20080814/0ff9449a/attachment-0001.htm _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user