Help me identify alternator whine?

Feuerstoss · 11-24-08, 03:53 AM

Alright... to get to the point, I just installed a small system in my car. Here's a quick rundown of the specs:

Bose 2100 head unit(Yes, the LS externally amp'd head unit. Yes, I got it to work with aftermarket 4ohm components)

800W 4ch amp driving four Alpine Type S 6.5" rounds.

200W 2ch amp driving an 8" JL Audio sub in a bandpass enclosure.

Power line is run down the driver's side(through the hole near the vacuum canister, into the car through the fusebox harness, and then following the OEM wire 'tunnel' all the way to the trunk), all other wiring is run down the passenger's. Amps are grounded to two separate spots in the trunk. I might not have sanded down everything completely, so this might be a culprit.

Now... I've got a very slight alternator whine. It's not all that noticeable, but does get annoying after a while. Isn't very pronounced unless it's above 4K RPM or so. The whine occurs whether or not the stereo is on, and doesn't seem to increase in volume either way. Any particular culprits that might be doing this?

car2n · 11-24-08, 04:36 AM

Quote:

Originally Posted by Feuerstoss

Alright... to get to the point, I just installed a small system in my car. Here's a quick rundown of the specs:

Bose 2100 head unit(Yes, the LS externally amp'd head unit. Yes, I got it to work with aftermarket 4ohm components)

800W 4ch amp driving four Alpine Type S 6.5" rounds.

200W 2ch amp driving an 8" JL Audio sub in a bandpass enclosure.

Power line is run down the driver's side(through the hole near the vacuum canister, into the car through the fusebox harness, and then following the OEM wire 'tunnel' all the way to the trunk), all other wiring is run down the passenger's. Amps are grounded to two separate spots in the trunk. I might not have sanded down everything completely, so this might be a culprit.

Now... I've got a very slight alternator whine. It's not all that noticeable, but does get annoying after a while. Isn't very pronounced unless it's above 4K RPM or so. The whine occurs whether or not the stereo is on, and doesn't seem to increase in volume either way. Any particular culprits that might be doing this?

Well if this problem was not there before the system installation then you can start by disconncting power to each of the power consuming components (one at the time) that way you will find out which or if any of these are causing the problem if not of them is doing it then might be that alt. is going out...

Feuerstoss · 11-24-08, 04:38 AM

Quote:

Originally Posted by car2n

Well if this problem was not there before the system installation then you can start by disconncting power to each of the power consuming components (one at the time) that way you will find out which or if any of these are causing the problem if not of them is doing it then might be that alt. is going out...

Yeah... the whine is definitely related to the sound system install. Wasn't there before I did the work, and is now there after. I'm only running one power line; I've got a distribution block splitting the juice to the amps.

antik · 11-24-08, 07:49 AM

Ground both amps to the same point. Do verify that ground point is clean. I sand until I've accomplished almost a mirror-like finish.

Feuerstoss · 11-25-08, 02:24 AM

Quote:

Originally Posted by antik

Ground both amps to the same point. Do verify that ground point is clean. I sand until I've accomplished almost a mirror-like finish.

Thanks! Once I manage to snag a few spare moments(job is being an absolute bastage right now) I'll do so and report back.

Biggg72 · 11-28-08, 11:58 AM

Quote:

Originally Posted by antik

Ground both amps to the same point. Do verify that ground point is clean. I sand until I've accomplished almost a mirror-like finish.

if this doesnt fix it, im not sure what kind of external amp that radio has, but if its like a factory amp, and you didnt bypass it, it is very possible that you have the whine from going from the radio to ext. amp to aftermarket amp. also did you use a good set of rca's.

on a side note if you happen to buy an aftermarket radio ground this radio to the same spot as the amps, use like a 14 g wire

djspawn00 · 11-29-08, 04:53 AM

last time I had this issue I upgraded all of my grounds to no avail... i should've just checked my RCA's turned out better RCA's solved my problems.

Old School · 12-11-08, 01:59 AM

From my experience with audio installation...
All Ground wires - if not properly grounded = noise
Cheap RCA wires with bad insulation or connection = noise
Amp with bad grounding points = noise
Amp turn up to high = noise
Bad speakers = noise
Cant think of anything else at the moment...

DrDave · 12-21-08, 12:17 AM

I would like to see you run the amo grounds all the way back to the battery. Local grounding in the trunk turns the chasis of the car into the ground path.

Dave

bsmooth1027 · 12-30-08, 11:05 PM

check ur grounds

bsmooth1027 · 12-30-08, 11:07 PM

Quote:

Originally Posted by DrDave

I would like to see you run the amo grounds all the way back to the battery. Local grounding in the trunk turns the chasis of the car into the ground path.

Dave

THE GROUNDS SHOULD BE NO LONGER THAN 18 INCHES OTHER WISE U GET NOISE

antik · 12-31-08, 11:41 AM

Quote:

Originally Posted by DrDave

I would like to see you run the amp grounds all the way back to the battery. Local grounding in the trunk turns the chasis of the car into the ground path.

Dave

Fixed. This contradicts my understanding of the normal install practice (though, you do have far more electrical experience than I do.) However, doesn't the ground off the battery affix to chassis in the Legend making the chassis the absolute 0 anyway? If so, wouldn't similarly grounding the amps to the chassis be a common (albeit large) ground as desired?

Quote:

Originally Posted by bsmooth1027

THE GROUNDS SHOULD BE NO LONGER THAN 18 INCHES OTHER WISE U GET NOISE

This is the rule of thumb I learned as well... sans yelling.

DevanTheDude · 01-04-09, 04:06 PM

I just read your system layout and I may be able to help. Some amps don't like having a direct input setup like you've built with the OEM Bose radio. You can narrow it down to the amplifier pretty easily. First off, disconnect the RCA's from the amp. The noise should go away, obviously. If it still remains, you are picking it up through the power wire-pretty unlikely. strip back some wire on both sides. while the car is running and the sound is happening, plug the rca's back into the amp. ground the outer shield of the rca inputs (negative side) using the peice of wire. If that eliminates it, you may have to modify the wiring harness you made to create a common ground for the input signal. Some amplifiers don't ground the input stage (Rca inputs) internally, causing this issue. Aftermarket decks will remedy this situation, but with the OEM Bose, you may have to "trick" it. Hope that made sense, Pm me if your confused at all I'll try to help

11-24-08, 03:53 AM	#1 (permalink)
Feuerstoss Autobahn-ed. Join Date: Aug 2006 Location: Co. Springs, CO Posts: 767 Car 1: 1991 L Coupe 5MT iTrader: (2)	Help me identify alternator whine? Alright... to get to the point, I just installed a small system in my car. Here's a quick rundown of the specs: Bose 2100 head unit(Yes, the LS externally amp'd head unit. Yes, I got it to work with aftermarket 4ohm components) 800W 4ch amp driving four Alpine Type S 6.5" rounds. 200W 2ch amp driving an 8" JL Audio sub in a bandpass enclosure. Power line is run down the driver's side(through the hole near the vacuum canister, into the car through the fusebox harness, and then following the OEM wire 'tunnel' all the way to the trunk), all other wiring is run down the passenger's. Amps are grounded to two separate spots in the trunk. I might not have sanded down everything completely, so this might be a culprit. Now... I've got a very slight alternator whine. It's not all that noticeable, but does get annoying after a while. Isn't very pronounced unless it's above 4K RPM or so. The whine occurs whether or not the stereo is on, and doesn't seem to increase in volume either way. Any particular culprits that might be doing this? __________________

11-24-08, 07:49 AM	#4 (permalink)
antik Obsessive Enthusiast Join Date: Sep 2004 Location: Northern VA Posts: 4,188 Car 1: 98.5 BMW M3 Coupe 5MT Car 2: 95 L Sedan Car 3: 95 6MT Coupe (Dad's) iTrader: (5)	Ground both amps to the same point. Do verify that ground point is clean. I sand until I've accomplished almost a mirror-like finish. __________________ ~Ben Canterbury Green '95 Auto L Sedan ADDCO \| MLS \| KNUKONCEPTZ \| ALPINE \| ECLIPSE \| JL AUDIO \| BOSTON ACOUSTICS Legend Owners' Rule #1: Do not drive an overheating Legend.

12-11-08, 01:59 AM	#8 (permalink)
Old School Registered User Join Date: Feb 2008 Location: Mile High Above Sea Level Posts: 181 Car 1: Kat Car 2: Jade iTrader: (2)	From my experience with audio installation... All Ground wires - if not properly grounded = noise Cheap RCA wires with bad insulation or connection = noise Amp with bad grounding points = noise Amp turn up to high = noise Bad speakers = noise Cant think of anything else at the moment... __________________

12-21-08, 12:17 AM	#9 (permalink)
DrDave Registered User Join Date: Nov 2006 Location: Bothell, WA Posts: 693 Car 1: 94 LS Coupe' Car 2: 91 NSX Car 3: various cars & bikes iTrader: (1)	I would like to see you run the amo grounds all the way back to the battery. Local grounding in the trunk turns the chasis of the car into the ground path. Dave __________________

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11-29-08, 04:53 AM	#7 (permalink)
djspawn00 Registered User Join Date: Nov 2008 Location: New York Posts: 30 Car 1: 2002 Lexus GS300 Car 2: 1998 Toyota Corolla Car 3: 1994 Legend Coupe iTrader: (0)	last time I had this issue I upgraded all of my grounds to no avail... i should've just checked my RCA's turned out better RCA's solved my problems.

12-30-08, 11:05 PM	#10 (permalink)
bsmooth1027 Registered User Join Date: May 2006 Location: new york Posts: 342 Car 1: 1992 ls pearl white iTrader: (3)	check ur grounds

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