Stereo Noise
Thread Starter
Racer
Joined: Aug 2006
Posts: 363
Likes: 3
From: Norwalk Ca
Stereo Noise
Installed an after market sound system in my 72 coupe. System consists of Alpine head unit, 10 inch sub, Diamond Audio separates in the front, Diamond Audio 6x9 in the speaker box and an Alpine 5 channel amp. When I put the car in gear or just driving down the street, I hear a scratching sound coming from through the speakers. Kind of like a power wire hitting metal. I went through all the stereo wiring with the stereo shop and all of the stereo connections are good. Can it be a possible bad ground on the car causing the noise? Any input or suggestions on possible causes are appreciated.
Thanks
Thanks
Racer
Joined: Aug 2013
Posts: 339
Likes: 54
From: Fayetteville NC
Does it sound scratchy when just idling? I'm far from being an expert on this topic but, My 72 did the same thing and I cleaned the antenna grounding under the diver's side quarter panel. Replaced the antenna wire to the stereo. My noise went away. They say if you have a MSD ignition system, that could cause a problem and will need an electronic filter. Check all your grounding. Good Luck!
Pro
Joined: Jul 2002
Posts: 589
Likes: 8
From: Palm Bay FL
I just delt with this not to long ago. Mine was a whine that increased with speed yours I think is coming from the distributor or 6al box. I think yours is different but what I did may work. The stereo shops no nothing they couldn't help so I told them what to do. I had them run the RCA cables on the right side and the power cables on the left. The power to the head unit was run from the battery as was the ground. I put a power filter on the power from the head unit and one on the yellow wire which keeps power to the unit for your stations. I also put a ground loop filter on the RCA cables at the head unit. This solved my problem. There is a bunch of info on here about noise just do a search on "radio noise".
Le Mans Master
Joined: May 2003
Posts: 8,875
Likes: 3,555
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
When you say scratching noise-
Do you mean constant - or does is go up and down with volume?
Most likely-
A bad/ loose something internally in the amplifier-
A bad set of RCA cables-
Or a bad speaker tensile lead or shorting out to a metal surface - or bad/rubbing voice coil-
You need to follow these steps or you'll be chasing your tail...
BTW- I use to do this for a living...
First you need to separate the system out-
Disconnecting all the pre-outs -
If you have noise still- tap on the amplifier and see if you can cause the noise. Tap on the radio-mess with the RCA cables to see if anything changes.
No noise-
Start by plugging one RCA in at a time till the noise comes back- try the sub-out first-as an educated guess that might be your problem.
No noise- start adding plugging one pre-out at a time till the noise returns.
Once you have found the pre-out that causes the noise- swap it with another RCA-
Still noise- look at the speaker- remove it from its mount-then disconnect one of the leads- see if that stops it
OR
No noise- look at the RCA cables ends
Then report back what you have found.
Richard
Do you mean constant - or does is go up and down with volume?
Most likely-
A bad/ loose something internally in the amplifier-
A bad set of RCA cables-
Or a bad speaker tensile lead or shorting out to a metal surface - or bad/rubbing voice coil-
You need to follow these steps or you'll be chasing your tail...
BTW- I use to do this for a living...
First you need to separate the system out-
Disconnecting all the pre-outs -
If you have noise still- tap on the amplifier and see if you can cause the noise. Tap on the radio-mess with the RCA cables to see if anything changes.
No noise-
Start by plugging one RCA in at a time till the noise comes back- try the sub-out first-as an educated guess that might be your problem.
No noise- start adding plugging one pre-out at a time till the noise returns.
Once you have found the pre-out that causes the noise- swap it with another RCA-
Still noise- look at the speaker- remove it from its mount-then disconnect one of the leads- see if that stops it
OR
No noise- look at the RCA cables ends
Then report back what you have found.
Richard
Thread Starter
Racer
Joined: Aug 2006
Posts: 363
Likes: 3
From: Norwalk Ca
Thanks for the input. We pulled the stereo, pulled out the speaker box and checked all of the wiring. Tried removing RCA cables one at a time as well as plugging in a new RCA cable. The noise is a scratching sound that comes through the speakers when I put the car in gear or go over bumps. The power wires are hooked up the battery directly as well as the ground (I think) for the stereo. Any other electrical systems on the car that can cause this? The noise occurs whether I'm listening to the stereo or my Ipod.
When you say scratching noise-
Do you mean constant - or does is go up and down with volume?
Most likely-
A bad/ loose something internally in the amplifier-
A bad set of RCA cables-
Or a bad speaker tensile lead or shorting out to a metal surface - or bad/rubbing voice coil-
You need to follow these steps or you'll be chasing your tail...
BTW- I use to do this for a living...
First you need to separate the system out-
Disconnecting all the pre-outs -
If you have noise still- tap on the amplifier and see if you can cause the noise. Tap on the radio-mess with the RCA cables to see if anything changes.
No noise-
Start by plugging one RCA in at a time till the noise comes back- try the sub-out first-as an educated guess that might be your problem.
No noise- start adding plugging one pre-out at a time till the noise returns.
Once you have found the pre-out that causes the noise- swap it with another RCA-
Still noise- look at the speaker- remove it from its mount-then disconnect one of the leads- see if that stops it
OR
No noise- look at the RCA cables ends
Then report back what you have found.
Richard
Do you mean constant - or does is go up and down with volume?
Most likely-
A bad/ loose something internally in the amplifier-
A bad set of RCA cables-
Or a bad speaker tensile lead or shorting out to a metal surface - or bad/rubbing voice coil-
You need to follow these steps or you'll be chasing your tail...
BTW- I use to do this for a living...
First you need to separate the system out-
Disconnecting all the pre-outs -
If you have noise still- tap on the amplifier and see if you can cause the noise. Tap on the radio-mess with the RCA cables to see if anything changes.
No noise-
Start by plugging one RCA in at a time till the noise comes back- try the sub-out first-as an educated guess that might be your problem.
No noise- start adding plugging one pre-out at a time till the noise returns.
Once you have found the pre-out that causes the noise- swap it with another RCA-
Still noise- look at the speaker- remove it from its mount-then disconnect one of the leads- see if that stops it
OR
No noise- look at the RCA cables ends
Then report back what you have found.
Richard
Thread Starter
Racer
Joined: Aug 2006
Posts: 363
Likes: 3
From: Norwalk Ca
Forgot to add, the sound is definitely not your typical alternator sound that varies with engine speed. The noise is not constant, seems to be something that is loose and will occur as the car has movement. All connections and RCA cables for the sound system have been checked.
The installer thinks the cause is somewhere else in the car. He's a very sharp guy and knows his stuff, so I do tend to agree with him. I worked with him as he checked out the sound system looking for the noise. He double checked everything.
The installer thinks the cause is somewhere else in the car. He's a very sharp guy and knows his stuff, so I do tend to agree with him. I worked with him as he checked out the sound system looking for the noise. He double checked everything.
Thanks for the input. We pulled the stereo, pulled out the speaker box and checked all of the wiring. Tried removing RCA cables one at a time as well as plugging in a new RCA cable. The noise is a scratching sound that comes through the speakers when I put the car in gear or go over bumps. The power wires are hooked up the battery directly as well as the ground (I think) for the stereo. Any other electrical systems on the car that can cause this? The noise occurs whether I'm listening to the stereo or my Ipod.
Pro
Joined: Jul 2002
Posts: 589
Likes: 8
From: Palm Bay FL
Forgot to add, the sound is definitely not your typical alternator sound that varies with engine speed. The noise is not constant, seems to be something that is loose and will occur as the car has movement. All connections and RCA cables for the sound system have been checked.
The installer thinks the cause is somewhere else in the car. He's a very sharp guy and knows his stuff, so I do tend to agree with him. I worked with him as he checked out the sound system looking for the noise. He double checked everything.
The installer thinks the cause is somewhere else in the car. He's a very sharp guy and knows his stuff, so I do tend to agree with him. I worked with him as he checked out the sound system looking for the noise. He double checked everything.
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Le Mans Master
Joined: May 2003
Posts: 8,875
Likes: 3,555
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
OK-
Doesn't matter where the noise is being made-getting the noise on bumps tells me you have something defective and /or loose.
You need to find where it's entering the system as you have the same manufacturer of the HU and amp- it should not have noise...
So if you disconnected ALL of the RCA's at the HU -do you still have noise?
If you disconnect the RCA's at the Amplifier- do you still have noise?
If you do- tap on the amp and see what happens- I think you have either a cold solder joint- bad connection internally to the amplifier and it needs to be replaced.
Let me know-
Richard
Doesn't matter where the noise is being made-getting the noise on bumps tells me you have something defective and /or loose.
You need to find where it's entering the system as you have the same manufacturer of the HU and amp- it should not have noise...
So if you disconnected ALL of the RCA's at the HU -do you still have noise?
If you disconnect the RCA's at the Amplifier- do you still have noise?
If you do- tap on the amp and see what happens- I think you have either a cold solder joint- bad connection internally to the amplifier and it needs to be replaced.
Let me know-
Richard