Sort of OT I suppose but I have a new noise in my audio system- all Alpine equipment. I think it developed during a recent road trip. At any rate, it has not always been present. The noise is a whine and fluctuates with RPM. The higher RPM, the higher the noise. I assume a noise filter is bad someplace in my system. Is it in the deck, the amp or elsewhere? Why did it suddenly appear?

 

Just a thought. I cleaned the battery ground in the rear of the car. Oddly the ground for the amp is connected there as well. The noise started after that. Coincidence?

 

I have the same exact problem. I have a head unit driving two amps, one 2x45w for the mains, and one bridged 220w for the 10" in the back. The 2x45 is up front and the 220 is in the back (grounded there). I have this whine that is amazingly loud if and only if I let the engine idle for a bit when I start it up without blipping the throttle to "engage" the alternator. When that happens, it's unbelieveably loud. Even when it's mostly behaving, it still has a whine.

I've been meaning to track this down as well. I'll let you know what I find. So far I think it might be a ground loop involving the remote power wire and/or the audio cable between the 220 & the head unit.

The 2x45 doesn't whine if I disconnect its inputs from the head unit (leading me to believe the head unit is causing the whine in its preouts). It is not volume dependent.

Another thing, how's the output of your alternator? I've heard that if one of the 6 diodes flakes, you get reduced output and more output fluctuation. Mine never goes above an indicated 12v (on the cluster voltmeter). Could be your problem too, though I do suspect that nice squeaky clean ground...

 

Same here all Alpine equipment (OEM) and RPM noise!?

 

Is all your equipment grounded at one point or different points?

The noise you describe is typically caused by ground loops...... A difference in voltage potential in the ground path from one component to another.

Boyce, when you cleaned the ground to your battery, you probably changed the potential characterictics of the amplifier.

A quick and dirty way to check if this is the cause..... Disconnect the current gound wire at the deck and run a ground wire (12 ga.) from the deck to the amp grounding point. See what happens and report back.

Rarely do the filters fail as they are a simple inductor.

HTH,
Scott

 

Been there done this many a times. It is alternator whine.....and very common in a lot of car stereo installs. To get rid of it I have always done the following:

1) Use VERY good cables all the way around. From
the patch cables to the power cables, etc.
A cheap pair of patch cables will let more
noise in then you can imagine.

2) Always run the patch cables away from the
power cables and away from any other sources
of power for the car accessories. Also try
and run the amp power cables away from any
other source of power.

3) Use short runs if possible for AMP power, the
shorter the better, and always connect to the
battery for the positive side and a good
frame ground for the negative side.

4) Try and connect every stereo item to the same
ground point......sometimes hard, but will
help.

Nine times out of ten the above will reduce the noise to very low levels. To get rid of it 100%
you might want to add a noise filter to the power leads of the amp and head unit. Filters
like these can go up to 30 amps in capacity for small to medium amps, and I have even combined two in parallel to supply a large amp in the past.

Do a search on the web for noise filters and alternator whine, and you will find a wealth of
information on the subject.

 

Thanks all. On the way in this morning, I thought I might try moving the amp ground off the common with the battery and see if that helps. I'll let you know.

 

Stereo whine stinks! I had the same problem, but I cured it 100%. It takes some time and patience, but well worth it.

The two grounding points I have found the most success with the 928 is the: top of the elctrical panel ( used that for head unit ) and the rear of the car where the toolkit and ground strap bolt on (Amps,etc)

Use fat postive/ground gauge (8 preferably unless you add amps then I go right down to 4. If's it a BIG system use 0. I've gotten to the point that my postive/negative wire are always equal.

I totally agree with above post on patch cables. Don't go cheap! Gold, Gold! Use gold plated power blocks, too.

Use split loom to help keep wires tidy and separated.

For Boyce, you may have had simply a speaker wire come loose touching some metal. Don't go ripping everything out just yet.

Your system is only as good as your weakest connection! Good Luck.

 

Indeed your last statement is true. I moved the amp's ground from point rear ground strap and that fixed the problem. Only I had an arc/spark appear from the rear ground strap to a bolt on the rear wiper when I hit the starter. I had cleaned it but not well enough. Cleaning cured the spark but I left the amp ground at it's new location.

 

If you use an active cross over filter or a head unit with adjustable output and an external amplifier find out your best ratio between the volume settings of the head unit and/or x-over and the amp. Most off the times the alternator wine is picked up by the head unit. I put the amplifier to about 80% of the output volume and adjusted the cross-over to that. In that way the wine signal isn’t amplified that much. It also can help to connect the negative side (outside) of the signal connectors to the negative ground of the car. You can best test this by just using a piece of electrical wire and hold it against ground parts. (Don’t forget head unit chassis).