High-Pitched Whine

[vwPanda 10+ year member]

I bought a Memphis 16-MCD500 amp from marcusb419er and I'm getting a high-pitched whine. He said its probably my ground but my ground seems fine. Its wired @2ohm to a single Alpine Type-R 12 in a sealed 3/4MDF box. I have 4ga wire running from the battery to the amp and 4ga running from the amp to a seatbelt bolt for a ground(have tried another spot as well). I get 12.6V at the amp with the car off. The whine happens with the car in ACC or running and with and without RCAs plugged in. If I squeeze the amp while its making that noise, the pitch changes. Did I get a bad amp?

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[2loud4u 10+ year member]

If the noise is there with no Rca's plugged in and your ground is good it is the amp:crap:

You could try and ground the Rca's

Also try grounding the amp to a bolt on one of the rear strut mounts.

 

[vwPanda 10+ year member]

I tried running a ground all the way to the battery and it still makes the noise.

 

[Neptune 10+ year member]

I believe the battery is the worst ground there possibly is.

 

[blue93corsica 10+ year member]

I believe the battery is the worst ground there possibly is.

well thank god theres finally an expert in the building, how about instead of critisizing, help the man with a solution, well with your case, i wouldn't want to hear a solution if you think in fact the batt is a bad grounding location

 

[fawd06 10+ year member]

do u have ur rca cable on the same side of the power wire?

 

[squeak9798 5,000+ posts]

I believe the battery is the worst ground there possibly is.

The battery IS the ground. The only reason grounding to your chassis works as a "ground" is because the battery is likewise connected to the chassis. What does matter is the resistence of the path from the amplifier's negative terminal to the negative terminal on the battery. For smaller gauge wires (1/0ga or higher), the typical car chassis has less resistence over that length than the wire does. So in these cases, when the battery is located in the opposite end of the car, it's better to ground to the chassis than it is to run the wire all the way back to the front of car since the chassis has less resistence than the wire. But for larger gauge wire, the wire will typically have less resistence than the chassis. Which means in these types of situations, it's better to ground the amplifier directly to the battery than it is to ground to the chassis.

However, seatbelt bolts typically do make for poor grounds.

My suggestion would be to try muting plugs;

http://www.davidnavone.com/MutingPlug/Muting2.wmv

 

[ultimate157 5,000+ posts]

I believe the battery is the worst ground there possibly is.

I lol'd

 

[vwPanda 10+ year member]

OK I made 2 muting plugs and plugged them into my amp and it didn't change anything. Same sound with no RCAs, RCAs to headunit, and with muting plug RCAs.

 

[ultimate157 5,000+ posts]

OK I made 2 muting plugs and plugged them into my amp and it didn't change anything. Same sound with no RCAs, RCAs to headunit, and with muting plug RCAs.

Check the grounds for the amps.

 

[vwPanda 10+ year member]

Check the grounds for the amps.

I already tried running directly to the battery.