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Discussion Starter #1 (Edited by Moderator)
Hi all, my first post, so be gentle.

I have a factory Vauxhall Stereo (CD 70 Navi) which is fine by all means.

I installed a Parrot MKi 9200 about 8 months ago, and everything was great. (Sound Quality has never been amazing because of the internal amp on the Mki 9200) Dont get noise when connected directly to the speakers. I cannot use the line outs from the MKi as my CD Navi 70 doesn't have line in (as its too old by about 2 months)

Anyway.....

I wanted to increase the sound quality and decided to get 2 line converters, amp, cabling and so on.

Its all been installed and works great.... except for alternator, injector, and general background noise from electrics on the car.

There is minor noise when playing from head unit, but not so much that it ruins sound quality too much. When using the Parrot, the noise is increased dramatically.

These noises are almost always caused by an earthing/grounding problem, however I have tried everything I can think of.

Noise is apparent when bypassing Parrot
Noise is apparent when disconnecting Head Unit and using just Parrot. Which suggested amp or cabling... then...
No Noise when connecting RCA cable to iPod / iPhone (So thats ruled out AMP, and cabling)

I have run ground tests with battery disconnected.

Have got 0.000 Ohms all round from furthest points away as well. All grounding points are clean and completely free of corrosion.

I have tried running a ground between all units and still experience the same noise. Have also tried grounding RCA Shields at both ends as well.

Have tried 3 different RCA leads - down different sides of the car, even through the middle (Quite unsightly) The RCA's have never been alongside the power feed as to cause interference.

The only thing I haven't ruled out are the Line to RCA Adapters (Halfords ones). Before I go and spend money, is it plausible that these may be causing the interference? I was thinking of going down the route of an AudioControl LC2i or something similar, but I didn't want to commit unless it would resolve the issue.

I have searched around so much and everything I have come across I have tried....

I have attached an image which will hopefully help you understand the set up. Link here

Does any one out there have a similar set up or advice that they would like to share?

Ta muchly...
 

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A.O.N. - Platinum Member
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If the RCA converters are the ones I am thinking of then they are small with 5 wires on one end and an RCA connection on the other

They are pretty poor quality from my experience and I suspect they are causing your issue

in the past I have grounded them to the crash bar behind the glovebox, there is a factory ground there that is a good one, I suggest you ground them there.

However as a test what you can do is this..

Pull your dash apart and connect a temp wire from the ground on the RCA Converters to the negative on the battery, out the window and down the side of the car,

its not pretty but it will tell you if that is the issue or not



oh and welcome to the site
 

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Discussion Starter #4
Cheers for the quick reply. Thats exactly where the converters are grounded. And, yes I have tried direct to the battery as well.

Funny thing is though, when theres no ground on those converters, the audible level of noise is exactly the same as when it is grounded, as if the ground is making no difference. This was my main reason why I thought the converters are causing the problem.

Also.... I forgot to mention, I have tried a surpressor on the Parrot & Stereo, also tried a ground loop isolator at both ends of the RCA cable. Slowly running out of ideas....

Just for the record, the car is a 2007 CDTI 150 Design Astra.

Cheers all he same, maybe I'll go down the route of trying different converters first.
 

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A.O.N. - Platinum Member
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Does the noise change when the engine is started?

and if it does does it change again when the engine is reved?
 

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A.O.N. - Platinum Member
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How have you connected the AMP to the speakers?

have you just tapped back into the standard harness behind the HU, or have you ran new cables into the doors?
 

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Discussion Starter #9
Does the noise change when the engine is started?

and if it does does it change again when the engine is reved?
Yes, with ignition on, there is an audible background noise, when engine is started, I can hear alternator whine, injector ticking, and power steering.

Earths are all good all round.

Unfortunately theres no accessory position I can try as this is a keyless model. (Unless I'm missing something)

Phil....
 

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Discussion Starter #10
How have you connected the AMP to the speakers?

have you just tapped back into the standard harness behind the HU, or have you ran new cables into the doors?
Have tried direct to speakers - Polarity, correct, and also have tried through loom as well. Results the same either way, no audible difference.

:)
 

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A.O.N. - Platinum Member
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There is an accessory position on the keyless cars..

I can' tell you what it is as I dont have one, but I am 100% certain there is one
 

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Discussion Starter #13
There is an accessory position on the keyless cars..

I can' tell you what it is as I dont have one, but I am 100% certain there is one
Interesting, I'll read the manual and find out.... I press button once, that gives me the ignition, second press turns it off (Radio stays on, so maybe thats the acc pos?), and holding it down starts the beast....

:)
 

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A.O.N. - Platinum Member
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Interesting, I'll read the manual and find out.... I press button once, that gives me the ignition, second press turns it off (Radio stays on, so maybe thats the acc pos?), and holding it down starts the beast....

:)
Thats it,

One push will turn the ignition on, The radio not turning off will be the "Ignition Logic" setting on the HU itself
 

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Discussion Starter #15
Where have you earthed the AMP?
Tried 2 factory earths.... One by the fuse box, one by the n/s tail light. And a new one just created in the centre of the boot entry. Drilled, bolted, all clean and secure. the audible level is still the same in all positions. Ive put so much time into figuring this out, starting to wonder if it was the converters all along!
 

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A.O.N. - Platinum Member
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OK, simple check for you

Pull the RCA cables from the AMP and power everything up

If you dont get the noise It does point to the Converters, If you continue to get the noise its something else
 

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Discussion Starter #17
OK, simple check for you

Pull the RCA cables from the AMP and power everything up

If you dont get the noise It does point to the Converters, If you continue to get the noise its something else
Yup.... Done that.... Amp gives a clean sound with nothing connected! I wanted to rule out parrot & stereo as well, buts as they worked ok without the amp, maybe they have been ruled out already?

The more I think of it, the more im edging towards converters.... Any other suggestions rather than the Halfords ones, or is it worth paying the extra £££ for some AudioControl device or similar?
 

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A.O.N. - Platinum Member
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Does your amp have High level inputs,

If it does I would use them over RCA Converters every day
 

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Discussion Starter #19
Does your amp have High level inputs,

If it does I would use them over RCA Converters every day
Haha... hindsight is a wonderful thing! I had 2 choices of amp, one with High Inputs, and one without. I chose the one without in favour of getting the converters... stupid I know, but the amp was a steal at £50 from some dude selling it on Gumtree. He showed me it all working without noise as I made sure of that!
 
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