Alternator Whine Options

[GTS13]

Hey guys,
I just finished installing my new 6 channel amp but now have alternator noise. I've already redone my ground on the amp moving it to a different location even and that didn't fix it. I also bought a couple Ground Loop Isolators and those didn't fix it either so I returned them. Any other ideas on what to do? Only other thing I can think of would be to replace my alt with a bigger one?

The amp is a JBL GTO 755.6 II.

Thanks!

[BloodyStupidDave...]

Hey guys,
I just finished installing my new 6 channel amp but now have alternator noise. I've already redone my ground on the amp moving it to a different location even and that didn't fix it. I also bought a couple Ground Loop Isolators and those didn't fix it either so I returned them. Any other ideas on what to do? Only other thing I can think of would be to replace my alt with a bigger one?

Replacing the alternator is unlikely to help. It could be a alternator going home but short of replacing it, it will be hard to prove that is the cause.

You are much more likely to be on the right track looking at the ground loop. A quick and dirty way to fix this that often works is to disconnect the ground wire of the phono between the amp and the head unit on one end (it doesn't matter which end as long as you choose the same end for all the phonos running between amp and headunit).

If you are using home audio style figure-of-8 audio wire between your amp and you head unit, consider replacing this with high quality car audio coax cable. Coax cable has a central core for the signal and is surrounded with a ground screen.



The above picture shows a solid inner core and a steel and aluminium screen but the one you want has multi-strand inner core and copper screen. Make sure to get coax designated for high quality audio applications and make sure it has the foil screen as well as the braid (copper foil is okay).

Try running a dedicated negative (ground) wire directly between the amp and the head unit. Use the same type of wire as the negative wire feeding the amp. If the whine is still there, keeping the dedicated ground wire in place between amp and headunit, try disconnecting the negative wire between battery and amp (so that the return path for the amp is via the headunit). If the negative wire from the battery to the head unit isn't up to the job of taking the load for both devices then do the following instead:

Keeping the dedicated ground wire in place between amp and headunit, try disconnecting the negative wire between the battery and headunit (so that the return path for the headunit is via the amp). Don't do this if the negative wire from the battery to the amp isn't up to the job of taking the load for both devices.

Try providing a dedicated ground wire from the cage the head unit fits into, to either the grounding point for the amp, the grounding point for the head unit or back to the battery.

Try rerouting the phono wires between the amp and the headunit away from all other wires especially power wires.

Try buying some copper or steel overbraid and feeding the wires between amp and headunit inside the braid, then connect the braid to either the grounding point on the headunit or on the amp. Alternatively, you could wrap the wires in copper or aluminium foil and similarly connect the screen to one of the grounding points.



It really comes down to trial and improvement.

Further reading:
http://www.caraudiohelp.com/newsletter/alternator_whine.htm
http://www.termpro.com/articles/noise.html
http://www.crutchfield.com/S-NXNKOqJ7sih/tech/kb348.html
http://www.eham.net/articles/15113
http://www.talkaudio.co.uk/vbb/showthread.php?p=1949352

This post has been edited by BloodyStupidDavey: Aug 5, 2007 - 3:22 PM