Amplifier humming noise

[cyph3r]

I have this hum/whining noise that comes from the amplifier when it is powered on. This only happens when the car is started, it doesn't make any noise when the key is just turned to the "ON" position. I have tested with just the remote line and 12v and ground connected, no rcas. I have connected a few different amplifiers all brand new to test it out and they all do it. The whine noise seems to go with the rpm of the engine. I measured the resistance of the ground spot I use for the amp and it came to net 0.6 ohms, which from reading around it should be less than 0.5 ohms.

Would the resistance in the ground cause the hum I am experiencing?

I'm running 600 rms with new 4ga power and 16 inch 4ga ground wire as well.

[reedal]

Could be the ground. Is it a bare metal ground (no paint or rust or anything to create resistance)? Also, have you done the big three? Having your alternator case grounded to the frame may eliminate the noise.

http://www.stevemeadedesigns.com/board/topic/196811-alt-whine-cant-find-the-source/?fromsearch=1

[Skullz]

There are so many possibilities of the cause, but check all connections including those under the hood.

Also check and make sure your ground straps on the engine are good and not corroded to the point of them being broke off and dangling.

How old are the plugs and wires?

Check the easy and cheap things first before spending any money.

[cyph3r]

I haven't did the big 3 and alt case isn't grounded to the frame. Never thought of that before. The wires have never been changed I don't think. It is a 2005 and I bought it two years ago so I guess they're 10 years old lol. There looks to be a little oxidation on the tips of the ground wires from battery. The ground to engine is 0.1 ohms and the 4 inch ground from battery to frame is 0.2 ohms. Maybe that has some effect as well. But yes the ground for the amp is on bare metal.

[finkster]

This may help.

http://www.stevemeadedesigns.com/board/topic/178159-read-this-before-posting-about-speaker-whine/

[cyph3r]

Lol thanks for the replies guys.

Turned out it wasn't even the amplifier I was hearing. It's the fuel pump. I have a crown vic and it has that little shelf area in the trunk and I have the amp mounted up there so it's right above the fuel tank.

Still plan on doing the big 3 and grounding the alternator case. I think I have some kind of voltage drop issues affecting other parts of the car not working, which all seemed to stop working at the same time.