#277956 - 19/03/2006 00:10
Alternator whine...
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carpal tunnel
Registered: 13/02/2002
Posts: 3212
Loc: Portland, OR
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For the last little while, I've been having an awful case of alternator whine. When the empeg was out of sled, I got none. When the empeg was off, I got none. When the empeg was on (even paused), I got the whine. I discovered that one of the -ve speaker wires had come apart, and was no longer connected. A few weeks ago, I spent some time soldering all the wires onto the connectors (as opposed to just crimping). That didn't work. Today, I checked the grounding. There was still a lot of paint between connector and frame, so I sanded that down to bare metal. Still no luck. I gave up, and put everything back together. After that, I decided to adjust the gains on my amps, since they were far too loud for normal listening -- most of the time, I had the empeg volume nearly as low as it will go. After adjusting the gains, and turning the empeg up a bit closer to 0dB (well, it's now just past the middle, so that I still have some room to go up, if needed), I seem to no longer hear any whine. Empeg out of sled, no whine. Empeg off, no whine. Empeg on and paused, no whine. Empeg playing, no whine. So... does this make sense? Did the previous position on the gain controls just mean that the electrical sensitivity was such that the extra whatever from the alternator was causing problems? The problem seems "fixed", but is it really just "masked"? (Pardon my lack of use of appropriate terminology, but I don't really know anything about electrical systems. )
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#277957 - 19/03/2006 09:06
Re: Alternator whine...
[Re: canuckInOR]
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carpal tunnel
Registered: 20/12/1999
Posts: 31594
Loc: Seattle, WA
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Yes, what you said makes sense. Specifically, this:
Quote: most of the time, I had the empeg volume nearly as low as it will go
That means your amplifier gains were cranked way way way way way too loud.
Remember that all audio systems have a noise floor. By cranking up the amplifiers so high, you were simply amplifying that noise floor. All you've done is adjusted things properly for once. Poof, magic, now it sounds right.
Setting the amp gains properly is one of the first steps in troubleshooting a whine problem. It's in our installation FAQ as well as in pretty much every other noise troubleshooting guide I've ever seen.
Also, based on this statement:
Quote: and turning the empeg up a bit closer to 0dB (well, it's now just past the middle, so that I still have some room to go up, if needed)
At that point you could still stand to have the amp gains set even farther down. The ideal, best quality signal will be had when you are able to turn the empeg all the way up to 0db and that is exactly the loudest you would ever want to play the stereo when you're at 80mph on the freeway.
Quote: The problem seems "fixed", but is it really just "masked"?
No, it's actually fixed. Like I said, all systems have a noise floor. You were just cranking up the noise floor.
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#277958 - 20/03/2006 13:32
Re: Alternator whine...
[Re: canuckInOR]
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enthusiast
Registered: 18/02/2002
Posts: 335
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Luckily your problem was easily fixed. Some cars seem to have lots of wiring weirdness. Alternator , battery, general wiring are usually things to inspect when you have these problems.
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#277959 - 21/03/2006 02:55
Re: Alternator whine...
[Re: tfabris]
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carpal tunnel
Registered: 13/02/2002
Posts: 3212
Loc: Portland, OR
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Quote: Yes, what you said makes sense. Specifically, this:
Quote: most of the time, I had the empeg volume nearly as low as it will go
That means your amplifier gains were cranked way way way way way too loud.
Interesting -- because prior to this, I'd already turned them down about half-way from where the installer had them set.
Quote: Setting the amp gains properly is one of the first steps in troubleshooting a whine problem. It's in our installation FAQ as well as in pretty much every other noise troubleshooting guide I've ever seen.
/me goes and re-reads the FAQ.
I hadn't gotten that far before. I didn't actually notice the whine until I noticed that I was only getting audio from one side of the car. I had associated the two, and figured that the whine was a result of, or part of, the same problem, as opposed to realizing that it was actually a completely separate problem altogether. When I found the loose wire, my first thought was "more wires are loose". I think I also had a vague recollection of reading this portion of the ground-loop FAQ:
For instance, the common term "alternator whine" makes it sound like the problem is the alternator, but usually the real source of the problem is a ground loop.
Quote: Also, based on this statement:
Quote: and turning the empeg up a bit closer to 0dB (well, it's now just past the middle, so that I still have some room to go up, if needed)
At that point you could still stand to have the amp gains set even farther down. The ideal, best quality signal will be had when you are able to turn the empeg all the way up to 0db and that is exactly the loudest you would ever want to play the stereo when you're at 80mph on the freeway.
I actually have it so that it's the loudest I'd want to play the stereo when I'm loading and unloading stuff from the bed of the truck, which is quite a bit louder than when I'm going 80mph on a freeway. (Though they could still use a bit more adjustment further down, yes.)
Quote:
Quote: The problem seems "fixed", but is it really just "masked"?
No, it's actually fixed. Like I said, all systems have a noise floor. You were just cranking up the noise floor.
Cool. Now I have the terminology to match my reasoning.
Thanks for a very clear answer, and an FAQ that makes sense (especially now that I've actually had a real-life lesson in it.)
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#277960 - 21/03/2006 02:57
Re: Alternator whine...
[Re: eliceo]
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carpal tunnel
Registered: 13/02/2002
Posts: 3212
Loc: Portland, OR
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Quote: Luckily your problem was easily fixed. Some cars seem to have lots of wiring weirdness. Alternator , battery, general wiring are usually things to inspect when you have these problems.
Agreed. I found the one loose wire, and figured more of the same -- I thought I was just hearing things when a non-wiring solution fixed the problem.
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