New amp & components - loads of interference - SORTED

[Mark_Storm 0]

I've just finished installing a new amp and front components and am getting a major buzzing noise through the tweeters and a whining through the main speakers.

 

I've got the power cables, RCAs and remote cable running down the passenger side and the speaker cables running down the driver side. This worked fine with just the sub wired up but is causing loads of interference through the fronts. The noise only comes on with the engine running and seems to change note with the revs. I'm sure this is exactly the same way I had my golf wired up and had no problems.

 

I've only got 1 more evening to get this sorted before heading off to Germany, anyone know what the problem could be?

[JoBlob 0]

You need to seperate the power cable from the RCA cables, or buy a noise supressor specifically for this job.

 

I just turn my stereo up as its not that bad.

[bcstudent 0]

It's likely you're suffering from electrical noise induced into the RCA leads from the power cables. Run the power and RCAs down different sides of the car. Since it's being amplified at the end, you don't need a lot of induced noise to cause you a big headache.

 

* EDIT *

 

What he said ^^.... :)

[Cnut 0]

Make sure you have a good earth too cause a bad one can induce interferance

[Mark_Storm 0]

Been up since 5 re routing RCAs down the centre tunnel but made no difference. Tried the RCA for the sub and did the same so its not the cable. Amp controls did affect the noise; volume control obvioulsy and the low pass filter cut a lot of it out (not much good on components tho). Checked the earth and seems ok (I've fitted it between the rear seats and spare wheel)

 

Any mnore ideas? I'll have one more chance to look at it tonight and really want to get it done before setting off tomorrow.

[Cnut 0]

Is the earth touching bare metal on the car? If it is touching the metal with paint this will need to be scraped off so that it is grounding the bare metal.

[coolrado 0]

Running a new seperate power feed and ground to my headunit stopped the interference on mine, just used a cheap amplifier wiring kit.

I tried routing the cables seperately, noise surpressor, checked all the grounds ect... which usually works but a new power feed was the only thing that worked fo me.

 

Also check your RCA's for damage, or try another another cable if you can.

[andy 0]

Trod this path more than once, earthing is critical on the amp and HU. If you can't see shiny bright metal then you can't be sure its earthed properly. Between the back seats is fine but make sure its gleaming before you tighten it, don't just bolt it to the seat belt mounting point as it won't work generally. The other thing is try and substitute a different amp, just to eliminate the amp itself. I tried every possible thing before and it ended up being the amp itself. After seperating the cables, putting noise surpressors on HU and Amp etc, it was the Amp. The noise surpressors and separating the cables didn't actually make much of a difference at all, they merely masked problems generated elsewhere.

[bcstudent 0]

I assume the amplifier isn't grounded to the battery directly? If not, try connecting a temporary cable between the battery -ve and the amplifier. At least it'll prove the point one way or another without costing you a lot of time.

[yalan 0]

Absolutely spotless clean & solid earth mounting point.

 

Separate Power & RCA

 

Ensure RCA does not run along any other car cabling (such as ABS, fuel pump etc) wiring or it will pick it up.

Cross wiring at 90degrees.

 

That'll sort it. Surpressors are not the answer.

[Mark_Storm 0]

Re-located the earth, scraped down to bare metal etc. Still no difference. Can you test the earth with a multi-meter somehow?

 

Took it to sextons, tried a suppresor on the rcas, still no difference.

 

Don't think it's the amp as it only happens when the engine's running, sounds spot on when it's not running.

 

I am not sure how good the power/earth to the HU is. Don't get the same problem through the rear speakers which are still connected to the HU direct. Could it still be this?

 

Cheers for the the advice guys, not much i can do now before the trip but will pull it all apart when i get back and try all the stuff you've recommended.

[yalan 0]

Quickest test is to borrow another RCA and run it over the top.

I've fitted a fair few stereos & although not many had noise, one drove me crazy until I realized it was picking up the fuel pump where the RCA ran parallel to the cars harness for about 3" between the under-seat area into the boot. Found another route to the amp and hey-presto - interferance gone.

[JoBlob 0]

Although you have the cables run seperately do you have loads spare coiled up or something in the boot area and picking up interferance there somehow.

[dinkus 10]

Re-located the earth, scraped down to bare metal etc. Still no difference. Can you test the earth with a multi-meter somehow?

 

Took it to sextons, tried a suppresor on the rcas, still no difference.

 

Don't think it's the amp as it only happens when the engine's running, sounds spot on when it's not running.

 

I am not sure how good the power/earth to the HU is. Don't get the same problem through the rear speakers which are still connected to the HU direct. Could it still be this?

 

Cheers for the the advice guys, not much i can do now before the trip but will pull it all apart when i get back and try all the stuff you've recommended.

 

I take it you're coming to Germany, so I can take a look at it for you and we can try a few things there to find out where it's coming from. My money is on a cack head unit earth, but we can testipoos.

[andy 0]

Don't think it's the amp as it only happens when the engine's running, sounds spot on when it's not running.

 

I am not sure how good the power/earth to the HU is. Don't get the same problem through the rear speakers which are still connected to the HU direct. Could it still be this?

 

I'm not saying it is the amp but this is EXACTLY the symptoms I had with a dodgy amp, after spending weeks changing/checking everything else. Fine with engine off, intolerable noise/interference with the engine running. Its what you would expect tbh.

 

Secondly, your rear speakers are not running through the amp and are fine, hmmm...

[RaddoMan 0]

try earthing the case also

[.A.N.T. 0]

Secondly, your rear speakers are not running through the amp and are fine, hmmm...

 

 

That would be about right. The wires coming from the headunit amp wouldn't pick up the interference as easily as the RCA's as they have the higher current.

 

I'll second though that it could be a dodgy amp. I had a v12 Alpine one do exactly the same. Fine with the engine off, but picked up noise through one of the channels and not the other. Found that by wiggling the connection and sticking the cable in a position with tape alleviated it, until the tape gave up and the lead moved and the interference returned...

 

Try getting a second RCA lead and running it through the car, over the seats etc and see it that sorts it. Try wiring the amp directly to the battery, and then the RCA directly to that. So none of the leads go under the carpets. They shouldn't then pick up interference and then at least you know the amp is ok. Or drop the amp into someone else's car and see if it whines in there.

 

Regards,

 

Ant.

[mrbeige 0]

I've seen this many many times before with 'dodgy' amplifiers, and more commonly with cheap halfords style amplifiers. What is the make and model?

[.A.N.T. 0]

I've seen this many many times before with 'dodgy' amplifiers, and more commonly with cheap halfords style amplifiers. What is the make and model?

 

Mine was a V12 so wasn't a cheap one, though it was pretty old... Although compared to some I suppose it's the 'low' end of the market...

[mrbeige 0]

I've seen this many many times before with 'dodgy' amplifiers, and more commonly with cheap halfords style amplifiers. What is the make and model?

 

Mine was a V12 so wasn't a cheap one, though it was pretty old... Although compared to some I suppose it's the 'low' end of the market...

I've seen the ground plane go down on a V12 before, but it was really really old.

[Mark_Storm 0]

Cheers for all the comments guys. Just need a clear day at the weekend to have a go at this!

 

Its a JL audio Slash series amp so defaintely not a cheapo halfords job. Why would a dodgy amp pick up interference only when the engines running?

[andy 0]

In a word .....yes :) There is no interference there to pick up when the engine is off....

[junkie 0]

Just seen this, Mark i can honestly say it worked a treat in mine with no interferance at all and i never had a noise suppressor or anything fitted, i do now have interferance on the Phoenix Gold Titanium 1200/1 or the 1000/2 that i am using now and they were 1K plus amps, i had re done all the wiring to make it neater and it then had the problem on hissing and i know they are not dodgy amps just picking up something somewhere, tried all sorts with the wiring and earths etc to no avail, made it a little better but its still there.

 

I do hope you get it sorted mate.

[Mark_Storm 0]

Finally got a complete free day to have a look at this and have now got it all sorted. Thanks to everyone who chipped in with advice.

 

Tried pretty much everything you chaps said and everytime it was working fine. Finally ran it with all the normal cables but the headunit still hanging out all it also worked fine, pushed it back into position and interference came back. Only thing I could see was the back of the stereo (metal) was touching the metal plate sticking up at the back of the slot. Covered that in duck tape and all sorted :clap: . Cost = £0 which is a first!

 

Now sounds awesome and runs way louder than I can listen to :D . Got a pic of the boot, the rest of the install looks completely standard so thieving scum looking to make a quick buck will keep walking

 

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[junkie 0]

Glad its sorted Mark and thats given me something to try on mine now, damn you.

 

I had been thinking only yesterday that may be my issue but didnt know where to start.