Interference on sound system...

[CrippsCorner]

Hi thought I sorted my interference problem today, but alas it was not to be.

So far have tried...

• 
  Two different headunits
  Two different sets of RCA leads
  Two different remote leads
  Two different remote locations
  Two different earth leads
  Two different earth locations

What I get is whirring and squeaking through the speakers when the headunit is turned on. It's worse when stationary and at low speeds. I've had the same setup throughout five different cars and never had this problem before! Wondering what else I could try...

Could it be something to do with the amp being so close to the battery? This is the first car I've had with the battery in the boot.

Could it be a knackered amplifier? It is very old (15 years)

I've searched around online and most advice seems to point to earthing... but as you can see I've tried various different things there. Worth pointing out without the amplifier powered up (i.e. taking the fuse out) the sound system is perfect.

 

[Blackie]

I have to ask, but have you rubbed your earth point down and made sure the ring connector is getting a good "metal to metal" connection?

I assume you have but I had to ask. If so then maybe check the headunit earth point, perhaps it's got a little corrosion.

 

[CrippsCorner]

Not on the connection it's currently on... but I connected it up behind a panel in the boot where there are about 5 earth wires from the car's system going to; I'd assume it's good to go on that account!

 

[BoatNonce]

If the battery's been relocated to the boot, could you not try earthing directly to it?

 

[CrippsCorner]

I have tried that as well... or rather the point where the battery earth strap connects to the chassis.

 

[Goodj]

this might well fix it

 

[Blackie]

I didn't read the bit about the battery being relocated. Check the battery connection to the chassis, it's possible corrosion has set in if the job wasn't done properly.

How long is the battery earth cable?

Also check the live cables, and where they run in the car.

Do your RCA cables run alongside or close to any live feed cables? People often run RCA's and the "amp remote" cable side by side and this can cause the noise you mention, or in this case if the RCA's have been run close to the battery live feed it could do it.

 

[Blackie]

Oh, also whilst it's convenient to "hi-jack" an existing earth point, it's possible that this could cause the problem. With ICE your better off creating a dedicated earth point.

 

[CrippsCorner]

this might well fix it

I bought one of these, and yes it does work, to a point. It badly suppresses the subwoofer, rending it almost useless.

@Blackie sorry to clarify this is actually in a MINI, not a Clio... they all come with batteries in the boot!

Cabling wise, everything is completely separate. The RCAs run down the left side of the car. The remote runs from the top of the amp to the cigarette lighter in the left of the boot. The power runs down the amp to the battery underneath.

I'll see if I can make/find a better earthing point though

 

[Blackie]

Sorry my bad, you've maybe mentioned somewhere you have a Mini lol.

I'd guessed you'd probably installed the system "correctly" but I had to ask those questions just to rule it out, I hope I didn't offend.

Yea I'd go with a dedicated earth point, daunting to take a drill to a car, I know, but it's usually worth it!

 

[Goodj]

I bought one of these, and yes it does work, to a point. It badly suppresses the subwoofer, rending it almost useless.

Is this one of the supercharger minis?

 

[CrippsCorner]

 

[CorteZ_CTZ]

How long is the positiv wire for the amp? did you looped like a coil?The RCA s are routed with the positiv cable?

 

[Goodj]

Out of interest ,why are you running your remote-on from your lighter and not the remote wire from the head unit.

I'll take a wild guess at "ease of installation" given the 12v is in the boot, and I can't imagine it'd make the first difference in relation to this actual problem

 

[CrippsCorner]

How long is the positiv wire for the amp? did you looped like a coil?The RCA s are routed with the positiv cable?

It's probably only about 50cm. It's looped round once, if you could call it that, just to get round the corner if you will. RCAs the complete opposite direction to the positive.

Out of interest ,why are you running your remote-on from your lighter and not the remote wire from the head unit.

I'll take a wild guess at "ease of installation" given the 12v is in the boot, and I can't imagine it'd make the first difference in relation to this actual problem

I can't remember now lol. I did originally have it installed to the headunit, but I think I saw a cut in the cable or something... and you're right it was easier just to fix it up that way rather than start lifting carpets up again!

On another note, I found this I'm going to work through when I get a spare moment...

https://images.crutchfieldonline.co...learningcenter/articles/417/NoiseSuppress.pdf