New Car Stereo/ Speakers

[m0ssy]

At the weekend I put in a new car stereo which incorporates:

Alpine IDA X305 (Ipod unit)
Replacement 4" speakers for rear sides
Replacement 6" X 9" for MDF rear shelf
2 small Amps (40w rms) to power the new speakers
Alpine restricted space sub woofer (cant remember the model number)

Wiring consisted of 3 X RCA leads for each amp and sub.
Power lead
Earth lead
Remote lead (incorporated in the centre of one of the RCA's)

I connected the power lead to the positive connection on the battery

Wasn't sure what to use as earth so connected it to negative on battery.

I ran all wires together (RCA's, Power and Earth) down the passenger side gap between the bodywork and chassis and connected it all up at the back of the car expecting great results.

Unfortunately I'm suffering the most horrendous 'whining' noise coming through the Amps and into the 4" and 6x9" speakers. Following a bit of research online it was suggested that I should never run the power leads next to the RCA leads so have re-routed the power lead from the battery around the drivers side instead.

I switched it all on and that bloody noise is still there!!

So can anyone suggest what to do?

Do I re-route the the earth following the same route as the power lead around the drivers side and away from the RCAs?

Am I better off re-routing the earth to somewhere on the chassis of the car thus making it a shorter lead (best place I could see was a strut by the seatbelt on the drivers side, I could scrape the paint off and jubilee the earth lead to this)?

Will i need to run a new remote lead as the current one is part of one of the RCA's?

Is there a better earthing point than where ive suggested near the rear of the car?


Help!?!

[pete]

My setup has the power, earth, signal and remote leads all running together down the passenger sill and into the left side of the boot, and I don't get any noise at all. I know people strongly advise against this, but it's not always the culprit.

My first recommendation would be to start disconnecting components to isolate which one causes the buzzing. e.g. Does the noise go away without the sub or one of the two amps connected? It sounds like you may have a "ground loop" somewhere in the system; some digging on t'internet should turn up ideas on how to reduce the problem. Given that you have put in a good quality earth from the amps straight back to the battery, I would look first at the earth for the head unit.

If you're looking at re-routing the earth from the amp, then as short as possible is the normal recommendation, providing you can find a suitable connection point on the chassis close to the amps.

There's a helpful page here that I bookmarked ages ago: http://www.termpro.com/articles/noise.html

Good luck!
Pete

[m0ssy]

Hi Pete

The noise goes away when disconnect the RCAs from both Amps.

No noise in the sub.

Having read the link you provided I can give a bit more information. It is similar to an alternator noise. Pitch does adjust when the engine is on and adjusts with revs.

But the noise is a single pitch (and very loud!) when the igition is on and the engine is not running. So I can swith on the ignition and the noise will be there whether the head unit is on or off.

Does this help?

Edited by m0ssy on Tuesday 19th May 10:16

Edited by m0ssy on Tuesday 19th May 10:17

[pete]

In that case I would advise trying a new earth connection from the chassis of the head unit directly to the -ve of the battery. See if that sorts it.

[BDM]

You need really good earths... Also making sure they are not too long in length.

I would again not advise running power leads next to the RCA's but again you already know that. Is the head unit old? Once i found that my head unit was the cause of one of my issues.

At a starting point i would check my earths and the position. They are connected to bare metal?

I woudl advise you go to http://www.talkaudio.co.uk/ i learnt alot on there about car audio installs... Alot of good info and searches for alternator whine

[da_murphster]

Put up pictures of what you have done - might solve the whirring

(Ok probably won't but will help give me ideas for when I do my stereo)

Why did you need two amps? Separate one for the sub?

Where have you put the sub?

[dvs_dave]

Can I ask what the sub is you're using and where you've mounted it?

I'm looking to add a sub to mine and was wondering if there's enough space under the seats? How about the passenger footwell?

[m0ssy]

Ok got back yesterday and cracked on for a few hours but still had problems:

I have now earthed the sub, and both amps to a bolt above the petrol tank so have kept the earth lead very short.

I have isolated that the whining noise is coming from the Stereo following disconnecting the RCAs from the amps and the noise disappearing, I took the battery earth which is thick cable to the chassy of the stereo and switched on..... to my dismay the noise is still there!! and very loud!!

The funny thing is if I remove the earth from the stereo the noise reduces dramatically but is still there, but for some reason I am having to remove the earth from the stereo to do this??

Any ideas?

[m0ssy]

da_murphster said:

Put up pictures of what you have done - might solve the whirring

(Ok probably won't but will help give me ideas for when I do my stereo)

Why did you need two amps? Separate one for the sub?

Where have you put the sub?

Will put pictures up when jobs are completed, including pics of the new front grille

2 sets of speakers, restricted space so 2 mini amps

[m0ssy]

dvs_dave said:

Can I ask what the sub is you're using and where you've mounted it?

I'm looking to add a sub to mine and was wondering if there's enough space under the seats? How about the passenger footwell?

I wouldnt like to put anything in the passenger footwell Dave.

I sat in the passenger seat for the first time the other day when fitting this dam head unit and was suprised at the lack of space in there when the door is shut, in comparison to the drivers side so wouldn't want to make the passenger too claustaphobic!

[Chequred Demon]

Thinking "left field" and having had some engine earthing issues of my own, I would try temporarily earthing the engine to the chassis with a Heavy Duty "jump start lead" or similar (from the exhaust manifold to the battery negative is the easiest route) to see if that cures the noise. Could be the engine is using your new earths as the easiest route to ground?

[m0ssy]

Chequred Demon said:

Thinking "left field" and having had some engine earthing issues of my own, I would try temporarily earthing the engine to the chassis with a Heavy Duty "jump start lead" or similar (from the exhaust manifold to the battery negative is the easiest route) to see if that cures the noise. Could be the engine is using your new earths as the easiest route to ground?

Would this be the case...? the noise is there on ignition switch, regardless of whether the engine is on or not, when as soon as the ignition is switched on the high pitched whining is there, even when the stereo is switched off! but if i switch on the engine the noise will increase with the revs increasing...

maybe i should take it down sextons and admit defeat

[SteveTusc]

Does the noise follow the rev's when driving? That's a good indicator that the earth is being shared with the engines earthing.

edited- Opps, just read that the noise does follow the revs! Sounds like you need a better earthing point.

Edited by SteveTusc on Wednesday 20th May 13:09

[dvs_dave]

m0ssy said:

dvs_dave said:

Can I ask what the sub is you're using and where you've mounted it?

I'm looking to add a sub to mine and was wondering if there's enough space under the seats? How about the passenger footwell?

I wouldnt like to put anything in the passenger footwell Dave.

I sat in the passenger seat for the first time the other day when fitting this dam head unit and was suprised at the lack of space in there when the door is shut, in comparison to the drivers side so wouldn't want to make the passenger too claustaphobic!

Ok, fair enough. Are you using the Alpine SWE-1000 sub?

Where have you decided to mount it? I want to upgrade the sound on mine but want to keep the interior looking as OEM as possible.

Sounds like your amps are picking up HT interference from the coil pack which as others have suggested indicates a bad earth from the engine.

[m0ssy]

dvs_dave said:

m0ssy said:

dvs_dave said:

Can I ask what the sub is you're using and where you've mounted it?

I'm looking to add a sub to mine and was wondering if there's enough space under the seats? How about the passenger footwell?

I wouldnt like to put anything in the passenger footwell Dave.

I sat in the passenger seat for the first time the other day when fitting this dam head unit and was suprised at the lack of space in there when the door is shut, in comparison to the drivers side so wouldn't want to make the passenger too claustaphobic!

Ok, fair enough. Are you using the Alpine SWE-1000 sub?

Where have you decided to mount it? I want to upgrade the sound on mine but want to keep the interior looking as OEM as possible.

Sounds like your amps are picking up HT interference from the coil pack which as others have suggested indicates a bad earth from the engine.

Yes mate, its the model before that one (I took it out of my previous vehicle ages ago)

I guess it could be from the coil as suggested as this would explain why the noise starts on the ignition switching on as this does power the coil?

How do I give this a better earth connection?

Edited to say mounted right behind me in between all the speakers, looks great but in reflection would have been better off mounting it behind one of the seats for optimum sound as these things work best behind or under a seat

Edited by m0ssy on Wednesday 20th May 14:15

[dvs_dave]

Cool thanks. Where have you mounted the amps? In the boot?

As you mention that the noise stops when you unplug the RCA jacks from the amps it would indicate that interference is being picked up by the signal leads rather than through the power lines. Any half decent auto-amp should have built-in noise supression on the power supply so this can be ruled out for the mo.

Try mounting the amps as close as possible to the head unit with short sheilded signal cables. Long un-sheilded signal cables effectivly act as an interference antenna that your amps will pick up. If you don't want to go to the expense of sheilded cable you could try getting a couple of clip on ferrite beads (Maplin sell them) to suppress the interference however it won't be as effective.

Edited by dvs_dave on Wednesday 20th May 17:41

[m0ssy]

dvs_dave said:

Cool thanks. Where have you mounted the amps? In the boot?

As you mention that the noise stops when you unplug the RCA jacks from the amps it would indicate that interference is being picked up by the signal leads rather than through the power lines. Any half decent auto-amp should have built-in noise supression on the power supply so this can be ruled out for the mo.

Try mounting the amps as close as possible to the head unit with short sheilded signal cables. Long un-sheilded signal cables effectivly act as an interference antenna that your amps will pick up. If you don't want to go to the expense of sheilded cable you could try getting a couple of clip on ferrite beads (Maplin sell them) to suppress the interference however it won't be as effective.

Edited by dvs_dave on Wednesday 20th May 17:41

The RCAs are double shielded but will check them again tonight. Can't move the amps to the front as not enough room!

Luckily its in TVR Fix tomorrow for a tune up prior to Le-mans so I can get them to re-earth the coil/ engine.

Unless anyone here knows how I can do it and I will give it a go tonight?

[Robertjp]

Think there only two earth points, one on gearbox and one at rear of battery tray? Battery tray fairly easy to get to...not sure where the coil pack joins the earth circuit though....

[PetrolHeadPete]

Sounds like you are getting pickup from some
ecu or pod related signal
Can you remove the RCA cables and just
hook them up "directly" across the cabin
Shielded RCA cables should be pretty
good but it's still possible that if they run
right next to some nasty switching signal
they can couple it to the audio
Direct hook up would prove that

[SteveTusc]

Try connecting your ipod directly to your amp (assuming you have the appropriate lead). That way you can confirm if the issue is power/earth or signal related.