On Fri, Mar 14, 2008 at 12:21 PM, Chuck Robey <chuckr at chuckr.org> wrote: > If you were a reliable judge of noise, then you'd be right if it didn't get > better/worse when charging, but being in/out of a car hasn't the least to > do with it, noise from a charger system doesn't need to come from outside > itself (from the car) it can be self-generated by any switching power > supply, and they've gotten cheaper and cheaper, which means more and more > likely. Someone commented that car stereos don't have this problem; > that;'s because those designers KNOW they must operate in that environment, > and reasonably (because anyone could tell if they didn't) they design for > quiet in such environments. Sometimes, as in computer environments, it's > not always so that a key spec is audio level noise, so that can get thru. > Ask any engineer, what I'm saying is reasonable. It's *obviously not* charging, if it's not connected to any power source whatsoever other than its own battery. It's just as obvious that the source of the noise cannot be fixed with any power-source-related device for the same reason. How do you connect a GLI or anything else to thin air? Everybody seems to be focused on the car audio/power input aspects, when I've repeatedly said that this problem exists regardless of what line-in I try to connect to; car, home audio receiver, boom box, or wireless headphone transmitter, and that the presence or absence of external power input makes absolutely no difference. The only two situations where I don't get the noise are from the built-in speakers or any set of headphones. ... And *I'm* the one who said that *factory* car stereos don't have audio noise problems but aftermarket car audio components frequently do, and that there's clearly something other than ground loop at work because using the same wiring hookups should give the same result. If ground loop is really such a common problem and so easily/cheaply fixed, then why isn't an isolator built into every aftermarket unit? (Obvious answer: that's not really the problem...) > > There are two reasons that you say (below) that the ground loop isolator > might help noise, and they're both equally likely. One would indeed be > ground loop problems. The other would be impedance mismatch problems. You > might not care which fixes your problem, but if you jump at the easiest > guess, it's going to cost others who hit this problem (and rely upon your > assumtions) some woe, if their problem isn't fixed by such a solution, by > (for example) a ground-loop-isolation system that didn't incidentally fix > the impedance mismatch, something easily possible. ...and the "easiest guess" would be ground loop problems, because that's every car audio engineer/seller/installer's pet solution. It's both easy and cheap to remedy, never mind the fact that it's frequently *not* the problem and always has limited success... So how does one go about fixing an audio impedance mismatch with a GLI? Does than mean I'm going to have to rig up a special audio cable that is permanently wired into the vehicle via a GLI? What would the schematic look like? How does it translate to my home audio gear? Am I going to have to crack those open and hack their wiring? (Rigging it into the Nokia's power supply wouldn't work, because frequently the Nokia isn't plugged into it.) > > I can't tell you which it was, without further testing, but I CAN tell you, > from bitter experience, jumping to conclusions that aren't truly justified > can really burn the hell out of you. Just don't want to spread FUD. When > dealing with noise, it;'s ALWAYS a complicated subject, because there are > multiple sources that usually all contribute together. Sometimes, fixing > the worst one is enough, but if you're a real stereo enthusiast, well, you > get my implication? > Who's jumping to conclusions? You're the one trying to apply a pet solution to a situation to which it doesn't apply! > I'm pleased that your problem is fixed, though, and maybe that's sufficient > for you. > My problem is *not* fixed - no one has come up with anything that applies, much less works!
