-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Mark wrote: > I am very familiar with the ground loop problem, and this is not > related to that. Ground loop problems are a result of noise created by > other devices, whereas this noise is created by the Nokia itself. It's > also a completely different kind of noise - ground loops usually cause > a whine (that varies with rpm's in a running vehicle), but this is a > swishing white noise that seems to vary with the sound that the Nokia > is playing. Also, no other devices, including my standalone mp3 > player, exhibit this noise when connected identically. > > The reason the cassette adapter works is not because of isolation but > because of completely different power and impedance characteristics - > it's a lot closer to headphones than to a line input. Yoiu original complaint didn;t seemo to list that you were charging at the same time, I think that was guesses at by other respondents, which while it doesn't rule it out (you could possibly have skipped that part) it makes it a bit less likely. However, the possibility raised of impednace mismatch, that's a very large likelihood, and yes, it could possibly be corrected by the proper repeat coil (transformer) being put in the way, or even a well designed amp, though I would personally like the repeat coil idea bettter, it would be less likely to inject even more noise. I would hazard a guess that from the very superior way that those teeny little speakers sound in their native environment, they probably went to quite some bother to get a very good match there ... you'll need to be as exacting yourself if you want to maintain the quality. Nokia might respond well to a suggestion of supplying some aftermarket device to serve as an amp/volume control/impedance matcher, it wouldn't cost all that much probably, and would probably be worth it to buy. Be right up their alley, designing/building/marketing such an article. > > Mark > > On 3/13/08, Larry Battraw <lbattraw at gmail.com> wrote: >> On Thu, Mar 13, 2008 at 7:21 AM, David Hagood <david.hagood at gmail.com> wrote: >> > I have found that running the N800 through a ground loop isolator helps immensely - especially if you are charging the device as you use it. >> > >> > The Radio Shack ground loop isolator (RS #270-054) works well for this. >> >> >> Yes, this is key. The n800 will transmit noise via the headphone jack >> if you are charging at the same time, particularly when charging from >> something from something that can leak tiny amounts of AC current back >> to the amplifier. This is pretty much the case every time when >> charging and connected to a AC-powered amplifier or even a DC amp >> where you're using 120V inverter or 12V charger connected to the same >> battery. That's why it's minimized when using a tape adapter; there >> is very little AC coupling between the tape read head and the tape >> adapter. Like the ground loop islolator, an audio transformer will do >> the trick too (You'll need a 1:1 ratio on the windings). >> >> Just my 2 cents- >> >> Larry >> > _______________________________________________ > maemo-users mailing list > maemo-users at maemo.org > https://lists.maemo.org/mailman/listinfo/maemo-users -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFH2WrSz62J6PPcoOkRApxHAJ9CYEmNmPCPsQ3y3VmqL8uhsIgShACgn7Bp 01QgG5Srq2DFQl12BAg0sS4= =HfSd -----END PGP SIGNATURE-----
