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Guest Message by DevFuse

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alternator whine

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4 replies to this topic

#1 truk


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Posted 07 March 2004 - 11:26 AM

Got a 100 Watt amp plugged in at the battery running two 6x9s mounted behind the seat in back, but I got kind of tired of the alternator and whatever else electrical being picked up, so you hear it in the background.

Other folks had any whine when setting up an aftermarket system in a Soob?

Are we talkin' amp quality versus proper grounding? Bought mine on Ebay for cheap.

#2 EOppegaard


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Posted 07 March 2004 - 12:55 PM

Grounding can usually be a problem with el chepo amps. Another thing to remember is that your power source itself needs to be clean. If you are drawing power off of a lead somewhere that has a bad ground, or an "unclean" one, you will most always have alternator whine. You can also buy noise filters to put inline on your power leads which most always eliminate the problem.

I can also not stress enough...FUSE EVERYTHING! Your "100 Watt Amp" will turn into 100watts of molten firey plastic, along with the arching along the line, one day if something shorts to ground. Fuse close to the battery, as well as near the item itself in order to be safe on all ends. IF you are only going to fuse one, fuse close to the battery or other powersource.

#3 SevenSisters


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Posted 07 March 2004 - 05:31 PM

Here's an unworkabke option... but you could hook up 5 in parallel.

20-amp Noise Filter

$21.99 Brand: RadioShack
Catalog #: 270-055

I'd guess any mobile radio store could help you with a larger one that filters out alternator noise.


#4 truk


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Posted 07 March 2004 - 07:14 PM

I heard it is a general rule to ground the amp as close as possible to the unit, so I did so using one of the bolts for the drivers seat. The amp sits just under the seat.

Power is coming directly from the battery, which itself is grounded to the engine block.

Do these filters hurt the sounds you want to hear, cut out certain frequencies?


#5 Cougar


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Posted 07 March 2004 - 09:03 PM

The power filters will not filter the audio frequencies from your deck. The filters are installed to remove unwanted audible and unaudible frequencies in the DC power line to the amp. When there is this type of noise on the DC power it can be injected to the amplifier circuits, since they are run by the DC power, and you can hear it through the speakers.

The battery can act as a fairly good filter itself. You could try placing a 100 microfarad capacitor, with a 25volt DC rating, on the positive lead of the amp and place the negative lead of the capacitor to ground to see if that will remove the noise. If it works I would solder it to the inside of the amp if you are comforable about working on the inside.

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