interference but only when the engine is on

[bal]

ok so i have 2 amps in my boot
the 1st 100w powers 4 coaxial speakers
and the 2nd 400w powers the sub
when i dont turn the engine on the sound is clear and undistorted
but when i turn it over the sound gets a high pitch noise from the speakers. this noise gets higher with the revs of the engine.
also when i put the heaters on the noise is very high and very loud.

i have wired my signal cables down one side and my power down the other

this one has me stumped
any helpis much appreciated

[59 bhp is more than enough]

you need whats called a ground loop isolate or sound surpressor it just plugs in between your amp and phon cables. should clear it right up

[Bennai]

do you need a ground loop isolator for the sub or just speakers??

[Retepetsir]

Forgot the ground loop isolator for now....

How/where are your amps earthed? How is your headunit earthed?

[NeX]

i had this problem and i got a ground loop isolator and it went away but then i changed some of the wiring and now it's back :( i can't see how what i have done has effected the amps....

[Yorkshireman]

Hi, You MUST ground your amps to a CLEAN POINT (this means metal to metal NO paint/rust) if possible away from other earths ie tail lights. Also make the earths as close to the equipment (amps) as possible as the amp is picking up the charge volts from your alternator which is causing your "whistle" as it trys to find a way to earth itself. I hope this helps.

Yorkie:devil:

[Andy_S]

what yorkshireman says. Make sure your earth is as close to the amp as possible as the car is one big earth terminal.

[bal]

thanks very much yorkshireman ill change my earthing point and see if thereis any difference

Retepetsir - my hedunit is earthed just normally usingthe factory connector at the back of the HU does the HU need a better earth as you attach amps?
....... and my amps are earthed on the boot floor but i do beleive the cables could be shorter and closer to the amp

[richmicratwista]

yeah sounds like an earthing problem

[59 bhp is more than enough]

or you could jsut use a ground loop isolater for bout 15 quid and have done with it

[Retepetsir]

or you could jsut use a ground loop isolater for bout 15 quid and have done with it

That just attempts to hide the problem, not solve it.

99% of noise/interference issues are caused by bad earths.

If you want to, you can earth your headunit to a nice new clean point on the chassis, which should also improve things.

[James]

A ground loop isolator never worked with mine, however when mike rewired it all there were no problems whatsoever :)

Although it seems my head units power supply is faulty as I was getting that whine coming straight from the headunit, but when I swapped it for a nearly identical head unit (all wiring left the same) it was fine.

That reminds me I must ring Pioneer and chew their ear off about that, I only bought the thing in December!

[59 bhp is more than enough]

yeah but if you couple good earths with a sound surpressor your bound to get rid of the noise

[Yorkshireman]

I just thought on..... your RCA cables arn't running down the car with the power +ve cable because that will cause interferance (yes I know the RCA cable is screened but it still happens) many moons ago when I used to do ICE installs I pulled out the carpet and ran the power down the passenger side, the RCA's down the center (the tunnel), and the speaker cables (for the fronts) back up the drivers side (plus the RCA's where earthed and the speakers where twisted pairs). This stopped any "noise"on playback.:wasntme:

I know thats a LOT of work (best wait for the sun to come back) but it helps.

Yorkie:cool:

P.S. did you clean the earths (so they shined) when you moved them?? Has it helped?? :laugh:

[Retepetsir]

The power cable wont cause interference as it's running DC (not AC).

The speaker cables might though...