Subs rumbling/humming help

[Cabriochris]

I installed my ice this weekend, two 12 inch subs and an amp but I have a problem.

When the ignition is off all is fine and it sounds great. As soon as I turn on the ignition or start the car there is an interference somewhere and the subs give off quite a loud humming/rumbling noise. It kind of sounds like my exhaust rumbling away at the back, that kind of noise but its louder than the exhaust. I opened my boot and the subs are vibrating with the rumbling which is obviously causing the noise.
As soon as I turn the ignition off, all is fine again and the music plays normally without the rumbling.

This is the fourth car I have had this system in but the first time I have had this problem, its never done it before.

The only difference is that in the wiring this time round, my new head unit only has one RCA out from it therefore the red wire has gone into the head unit and then gone into the black hole in the amp. The black wire is free and not doing anything.
I did put the red to red first of all but that meant only one sub worked, with red to black both work.

Is it something to do with the wiring or could it be something different?
I'm not up on electronics but ive been told it doesn't make any difference if the RCA doesn't have a black output and that wire is therefore redundant.

Hope you can help.

 

[Russy B]

wot kind of rca cable u got, one with 3 connectors on it

 

[madmike1]

Will a faulty RCA cable (i.e a break in the cable) cause a whining/rumble like this?

 

[BrianR]

More likely to be a bad earth and pick up from something electrical when the engine is running.
Are the cables anywhere near the cars loom at the rear, as it could be the fuel pump its picking up.

 

[madmike1]

the noise happens when the engine is not running!the cables are not near the fue pump or the wiring loom

 

[Cabriochris]

RCA cable has two plugs on each end. One red, one black.

My earth is wired just behind the back seats, theres two screws at the back of the boot (nearest the seats) when you life the carpet up, one each site, cant remember what they are holding now but anyway its earthed onto that.

If its the earth what other easy places can be used to screw it onto. Will it damage anything if it is the earth and im still using it.

Anymore ideas the noise is driving me crazy it needs to be sorted.

 

[Cabriochris]

lol think my only difference is that the noise stops when you turn the ignition off, only humms when the ignition is turned on.

 

[BrianR]

the noise happens when the engine is not running!the cables are not near the fue pump or the wiring loom

Hang on, I just realsed theres two of you asking the same questions.

MIKE. Is it a set you can turn on without switching on the ignition ??

Chris. The pump runs as long as the ign is on, even if the engine is not running

 

[Cabriochris]

Yeah i know dont mean to be confusing, there are two post asking the same thing so just putting them into 1 i think.

If it is the fuel pump picking it up what do i need to do? run the leads somewhere else or re-earth or what?

 

[BrianR]

The best way to see if its the pump (or anything else) is to run some RCA leads outside the car from the h/u to the amp and see if it goes.

You can do the same with power leads.

You could be picking up all sorts of noise if the leads run along side the cars wiring so this is the easiest way to pin it down.

 

[Cabriochris]

Ah hassel but what can you do.

Someone suggested this, what do you think?

http://caraudiosecurity.com/shop/product/products_id/2757.html

 

[madmike1]

I have all of the wires going down the middle of the car atm on top of the seats so that they are not toucing or next to anything. the noise happens when the ignition is on and the dash lights up as well as with the engine running! when the key is turned to one click so that the HU works but the dash lights do not apear, the noise goes away and all is fine. So where can i be getting interference from?

 

[BrianR]

Ah hassel but what can you do.

Someone suggested this, what do you think?

http://caraudiosecurity.com/shop/product/products_id/2757.html

Sorry chris, It might be hassle but you cant cheat at this, you HAVE TO find the cause, would you paint tread on bald tyres ?

 

[Cabriochris]

Ah hassel but what can you do.

Someone suggested this, what do you think?

http://caraudiosecurity.com/shop/product/products_id/2757.html

Sorry chris, It might be hassle but you cant cheat at this, you HAVE TO find the cause, would you paint tread on bald tyres ?

True, a fun weekend for me then removing all the wires i only just put it

I will just have to see what i can do.

 

[Russy B]

are u positive that the noise is coming from your speakers/subs, as when ignition is turned on, u do get a humming noise like brian said. you might wanna get a better rca lead like an autoleads one

 

[BrianR]

Chris, why don't you beg borrow or steal another set of leads to do the test, just disconnect the ones in the car while you work and then if you can prove its not the cables, you haven't undone all the work unnecessarily.

 

[Cabriochris]

Yep as soon as you turn the ignition on the start humming, you go to the back of the car open the boot and you can see them/feel them rumbling so definatly the subs.

The set of leads i bought were not cheap, i have cheap ones in my last 3 cars and thought i would spend an extra £20 this time and this happens lol.
Ok well maybe try another RCA then and see what happens.

Thanks for your help, just hope it works.