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Alternator noise in speakers

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Old August 4th, 2018, 10:47 AM
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Default Alternator noise in speakers

Hi.
I got a 70 Chevelle, and just bought subwoofers and a amp. Both are new JBL.
The former owner mounted a hertz amp and speakers, and that is working fine. When I put in the subwoofers and the second amp, a hell of alternator noise came. I have tried everything now..
The earthing is well done on both amps, even tried to ground both amps and HU at the battery.
The battery is in the trunk BTW.
Rca and power is not lying together, and no crossing.
Tried with a new Rca cable outside the car, grounded the chassie and Rca together, but nothing takes the noise away.
If I disconnect the new amp, and just using the old one, everything is fine.
What to do???

350 with HEI distributor, and the power is taken from the ignition wires. Can it be that causing it?
Do I need to put an single power-wire from the battery to the HU?

Another thing, from when I bought the car. If I turn on the wipers, a pop comes into the speakers, what can that be?

Sorry for my written English, Norwegian here😃
Old August 4th, 2018, 11:22 AM
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Try a filter on the ignition if the electrical noise follows rpm. something like this
Old August 4th, 2018, 1:02 PM
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Thanks Kevin, maybe I`ll try one, but would have been fun to find the reason why also��
Old August 4th, 2018, 3:54 PM
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I think electrical noise is from the ignition. Old cars with points and AM radio had a shield (metal) that covered the points in the distributor for just that reason. What I posted a picture of is basically a capacitor. What that does is takes the AC to ground from the DC off the amplifier. The amplifier should just boost the signal from the receiver which is an AC signal.
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