I need some car audio electrical help *solved*

[ARCHIVED THREAD] - I need some car audio electrical help *solved*

Posted: 10/9/2001 7:41:44 PM EDT

I installed a new stereo and subwoofer in my truck today. The problem is that I am getting engine noise through the speakers. I have isolated the problem to the sub (no noise when sub disconnected). The noise is feeding back through the drivers powered by the head unit. The power is run on one side of the cab and the RCAs for the source are run on the other side. Could having a ground wire that is too long cause this? Tell me what you think I should do. Thanks.

Posted: 10/9/2001 7:54:18 PM EDT

[#1]

Sounds like ground problems, make sure that the amp is has a good ground to bare metal, no paint or carpet and crap like that. As a general rule make sure the ground wire is as short as possible but long ground wires arent necessarily always a problem.

One very important point though is make sure that if you have more than one amp that all of them are grounded at the [b]same spot[/b] even at the sake of creating longer ground wires. If not it causes problems and altenator whine.

Posted: 10/9/2001 7:54:27 PM EDT

[#2]

Not real good at this, just some lessons that I learned the hard way. Make sure that the ground wire goes to the frame or the battery, not a screw into plastic, etc. Don't use undersized grounding wire.

Hope this helps.

Jamie

Posted: 10/9/2001 8:00:17 PM EDT

[#3]

Self-powered subwoofer right? A bad ground on the SW could cause lots of current to flow though the RCA shields and cause problems. Try grounding the subwoofer chassis to the Neg battery terminal with a piece of heavy wire, see if it helps.

Posted: 10/9/2001 8:03:16 PM EDT

[#4]

need help with car audio???

(enter treetop)

Posted: 10/9/2001 8:04:12 PM EDT

[#5]

Thanks for the replies guys. I'll mess with the ground wire tomorrow.

Posted: 10/9/2001 8:10:31 PM EDT

[#6]

There are two sources of engine noise in car stereos - the generator/alternator and spark plugs/wires.

The generator/alternator will give you a high pitched whine or whirl which will change frequency with the RPM of the engine. This is normally caused by AC ripple voltage (not nipple voltage that's something different) coming down the (+) cable of the amplifier. This is cured with a large choke coil attached in line with the (+) cable close to the amplifier. There are kits sold for this, some include filter caps too. Get one matched to the current demand (in amps) of your amplifier.

Sparkplug/wire noise is a popping or crackling noise. Turning to an AM radio station will make the noise worse than FM or CD/Cassette normally. This noise is caused by the high voltages on your spark wires and can be cured with the use of high quality wires or resistor wires which are sold at auto parts stores.

I use to make my living 20 years ago doing custom car stereo installations and fought both these demons weekly.

Your ground wires shouldn't be longer than a foot or so. Find a nice heavy piece of the car chassis, scrape the paint, drill a hole, and use a star washer under the screw between the ground wire lug and car body.

Posted: 10/9/2001 8:14:56 PM EDT

[#7]

I am an EE and I know what to do. So does Paul, and he types faster. Heed his advice, it is spot-on.

Posted: 10/9/2001 8:53:50 PM EDT

[#8]

Under no circumstances should a properly functioning and properly installed head unit send noise through speakers powered by itself only when an external amplifier is being used to power another speaker. (Holy run-on sentence batman!)

Can you be more specific about what products you're using, and how the system is configured?

Posted: 10/9/2001 9:03:19 PM EDT

[#9]

While were on the topic...

I just bought a Pioneer system fer my car.

Nothing big- 2 6X9's and 2 small dash units.

The dash units are crackling prety bad..
Whenever a song hits some bass, it "crinckles" like it's blown. Thing is, it isn't blown. The dude who installed it said it's from teh mounting to the grate. Is tehre any way to fix this>?>?>?>?>?>?>?>

Posted: 10/9/2001 9:06:30 PM EDT

[#10]

Yeah. Turn your bass down, McHipHop.

Posted: 10/9/2001 9:09:10 PM EDT

[#11]

Seriously, Carrot Luver, have the dude put some capacitors inline with your front speakers. They are non-polar(as opposed to BI-polar like you), and they just get wired in series with the positive lead at the speaker.
Try something between 150 and 200 microfarads to start with. They work as a 6db/octave high-pass filter(read- BLOCKS THE BASS).

If the guy's clueless, I'd be happy to donate a couple to my Florida brother.[:)]

Posted: 10/9/2001 9:14:28 PM EDT

[#12]

Quoted:
Seriously, Carrot Luver, have the dude put some capacitors inline with your front speakers. They are non-polar(as opposed to BI-polar like you), and they just get wired in series with the positive lead at the speaker.
Try something between 150 and 200 microfarads to start with. They work as a 6db/octave high-pass filter(read- BLOCKS THE BASS).

If the guy's clueless, I'd be happy to donate a couple to my Florida brother.[:)]

View Quote

Dude, other than the fact that the entire post I just read may as well have been written in Swahili....

Does this mean that I am going to totally have to cut out all my bass????????????

I mean, I don't "boom" so it's not a major thing, but I can't totally cut out ALL the bottom from my songs. Isn't there a way to alter the grate that is making it rattle???

Posted: 10/9/2001 9:16:21 PM EDT

[#13]

Treetop,
I have an Aiwa head unit powering 2 Pioneer 6.5s in the doors and two 6x8s behind the seats. The speakers are using the factory wiring. I have a Bazooka with built in amp that is getting signal from RCAs from rear pre-outs on head unit. Power, remote and ground run to the driver side and signal RCAs run to the passenger side. Ground wire runs back to engine compartment.

The humming stops if the RCAs are disconnected from sub amp. But the sound seems to be coming from the Pioneer drivers because it is too high pitched to be generated from sub. It is also amplifying the sound of the CD player changing tracks.

Let me know if you need more info.

Posted: 10/9/2001 9:26:50 PM EDT

[#14]

Quoted:
...It is also amplifying the sound of the CD player changing tracks...

View Quote

Definitely sounds like a ground loop problem. First try an alternate ground location(for the bass tube) and see if it improves. Some people would suggest grounding the head unit at the same location as the amp. That may or may not help. You say the amp is grounded in the engine compartment. as a general rule of thumb, a ground wire should be grounded at the vehicle chassis less than 18" from the amp. The shorter the better. Try these things first, then if necessary we can try ground loop isolators, removing the negative lead from the RCAs, etc. Let me know.

McCarrots, I can't imagine expecting too much bass from your front speakers anyway. You'd still have the rears for low end reinforcement, but the fronts would only play from 200 hertz or so and up. Is this in the ranger? where exactly are the speakers located?

Posted: 10/9/2001 9:40:35 PM EDT

[#15]

Thanks Top. I'll try to shorten it up tomorrow.

Posted: 10/10/2001 1:06:47 PM EDT

[#16]

Thanks for all of the replies. I solved the problem by shortening the ground wire.

[ARCHIVED THREAD] - I need some car audio electrical help *solved*

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