DiyMobileAudio.com Car Stereo Forum banner

1 - 20 of 28 Posts

·
Registered
Joined
·
41 Posts
Discussion Starter #1
Alright folks, I've been messing with car audio for a while now, but my alternator whine has me stumped. The situation is as follows:

The car is 1996 Honda Accord 2.2L
I have two Boston Accoustic GT series amps feeding front comps and rear coaxes.
I also have one Alpine MRX-M240 for the subs.
My HU is the Pioneer DEH-80PRS. I may or may not have hot swapped rcas, but using bare wire to ground the jacks to the case provided no improvement.
My wiring has just been upgraded to a run of 100% Copper 2/0ga wire with 4ga wire going from a distribution block to each of the amps. I am currently using a rear seatbelt bolt for the grounding point--sanded of course. But none of that really matters because I had the same symptoms with my old wiring.
My rca cable is knukoncepts 4ch twisted pair. I have a separate rca cable for the subs.

First thing I did to try to pinpoint the problem was put shorting plugs on the ends of the rcas which would normally plug into the HU. Bingo, whine is gone. Naturally, one would think that the noise must be coming through the HU. So, I tried the usual. I grounded the HU first at the distribution block where the amps are grounded, and then also tried grounding it straight to the battery. Neither of these options provided any improvement. I then proceeded to unplug everything from the HU which I could (dimmer, antenna, aux cable)--no luck. Next I ran the ignition wire off the regular power wire to see if there was noise coming down that line--no dice. Finally I tried running power straight from the battery--no improvement there either.

I'm really stumped on this one. I even went so far as to replace my alternator (a whole separate ordeal which some of you may have read about) with no improvement there either. The last thing I can think of to do would be get a new battery. I would rather not spend any more money at the moment unless someone can convince me that it will have a good chance of fixing my problem. I had my battery tested at the local shop and they said it was fine. I measured it myself and it rests at about 12.25v and dips to 10.5v when starting the car. From what I've read these numbers are somewhat middle of the road. I'm not sure how old the battery is since I've only had the car for a couple of years, but it starts fine no matter how far below 0 it gets.

Any other ideas would be welcome. At one point I had put a filter on the HU's power line, but it was cheap and didn't really do anything. I have a 1f cap at my disposal, should I throw that in parallel with the HU?

The wine isn't horrible. It's really only when the windows are up and the music is low that it becomes a nuisance. If I can't solve the problem by winter I suppose I can just turn my gains down (they're pretty hot right now), but then I'll end up losing a little bit of volume..

Oh, one more thing. I don't know how common or well known this is (I couldn't find much when I searched on it originally), but the problem is only present when the alternator is charging the battery. The way my charging system works is it will bounce between 12.5 and 14.5 volts depending on the load on the system. It does this in order to avoid overcharging the battery, or so I've read. I am confident that 12.5v is not my battery voltage (and thus a bad connection) because I can turn the car off and see it drop to 12.2v or so. Anyway, the noise is only noticeable when the system voltage is 14.5 volts. Perhaps this points to the battery not being able to filter the noise above a certain voltage? I have no idea.

Thanks in advance for the help!
 

·
Registered
Joined
·
26 Posts
Hmm that is very strange, especially with the manually grounded headunit and staight power, considering it runs straight to the alternator. What gauge wire do you have from your positive terminal to your alternator? I had a little whine when I first had my system, but I got another battery up front and it cancelled any whine I had.
 

·
Registered
Joined
·
4,973 Posts
Did you try running the signal cables outside the car to the amps? Alternator whine is usually because of faulty grounding or signal cables too close to the car noisy electrical system. I believe it's the latter, noise induced in the signal cable.

If you wanna experiment, try placing a filter directly on the alternator to get rid of some of the noise, a 25V 470uF should do.
 

·
Premium Member
Joined
·
2,107 Posts
get u an ipod connect a 3.5 to rca up front into your rca's u have ran. try it while driving the car. report back
 

·
Registered
Joined
·
18,231 Posts
first get rid of the seat belt ground. not a good grounding point
 

·
Registered
Joined
·
104 Posts
Did you try running the signal cables outside the car to the amps? Alternator whine is usually because of faulty grounding or signal cables too close to the car noisy electrical system. I believe it's the latter, noise induced in the signal cable.

If you wanna experiment, try placing a filter directly on the alternator to get rid of some of the noise, a 25V 470uF should do.
I agree with the RCA's I have seen so many posts on alternator whine because they had the power wires near the rca's.

first get rid of the seat belt ground. not a good grounding point
I agree with that, I think the Accord has some bolts under the seat that are supposedly good grounding points.

Have you tried testing each source separately? Each amp, rca's, speakers wires. This could help pinpoint where the ground loop could be coming from.

You said you had the gains set high? Did you set them with dmm, oscilloscope or by ear? Try turning the gains down a notch and see if the whine goes away.

Last thing: older pioneer decks had an issue with RCA ground fuzes blowing in the head unit. This post shows how to ground the rca's to the head unit with small wire.
http://forum.realmofexcursion.com/head-units-processors-car-audio-electronics/27806-how-ground-your-h-us-rcas-pics.html
 

·
Registered
Joined
·
11,999 Posts
if the noise goes away when you unplug the RCAs from the amplifiiers 90% of the time this is a ground loop. you can try re-grounding things, but most of the time this doesnt help much.

easy test, get a $12 GLI and see if that makes the noise go away. if it does, then get some better isolation transformers for permanent use.
 

·
Registered
Joined
·
894 Posts
Do you have noise when the rcas are unplugged from the amp?
Try buying a cheap set of rcas and run them across the seats etc. and check each amp individually. See if the noise goes away. If so replace rcas. It sounds like a damaged RCA connection or wire to me. I have seen a bad amp create some weird issues like this too. Plug in all the amps sequentially and see when the noise comes back in. Then reverse order that will let you the problem amp.

Can you try to run things off of deck power easily? Try direct to speaker even just a crappy factory speaker free air to test for noise.
 

·
Registered
Joined
·
41 Posts
Discussion Starter #9
Hmm that is very strange, especially with the manually grounded headunit and staight power, considering it runs straight to the alternator. What gauge wire do you have from your positive terminal to your alternator? I had a little whine when I first had my system, but I got another battery up front and it cancelled any whine I had.
I have 0ga wire up front for the Big Three. Do you think getting a new battery would be the solution? Once again I don't want to spend the money if it won't fix things.

Did you try running the signal cables outside the car to the amps? Alternator whine is usually because of faulty grounding or signal cables too close to the car noisy electrical system. I believe it's the latter, noise induced in the signal cable.

If you wanna experiment, try placing a filter directly on the alternator to get rid of some of the noise, a 25V 470uF should do.
Would the noise induced in the cable go away when using shorting plugs? Because when I tried using plugs on the ends of the rcas which would normally plug into the HU the noise was gone. Also, I have my power wires on the passenger side and the signal wires on the drivers side so there shouldn't be any interference there. Yeah Ill just throw my 1 farad cap on the alternator and see what that does...

get u an ipod connect a 3.5 to rca up front into your rca's u have ran. try it while driving the car. report back
How is this any different than just using shorting plugs which I've already done?
 

·
Registered
Joined
·
41 Posts
Discussion Starter #10
Do you have noise when the rcas are unplugged from the amp?
Try buying a cheap set of rcas and run them across the seats etc. and check each amp individually. See if the noise goes away. If so replace rcas. It sounds like a damaged RCA connection or wire to me. I have seen a bad amp create some weird issues like this too. Plug in all the amps sequentially and see when the noise comes back in. Then reverse order that will let you the problem amp.

Can you try to run things off of deck power easily? Try direct to speaker even just a crappy factory speaker free air to test for noise.
Well I don't have noise with the shorting plugs so wouldn't that point to the noise coming from the headunit? Back in the day before I ran amps I used an Eclipse CD8443 and didn't have any noise running things off of deck power. I suppose that doesn't say much though.

if the noise goes away when you unplug the RCAs from the amplifiiers 90% of the time this is a ground loop. you can try re-grounding things, but most of the time this doesnt help much.

easy test, get a $12 GLI and see if that makes the noise go away. if it does, then get some better isolation transformers for permanent use.
Any GLI's you recommend? I'd be willing to spend a bit more than $12 for a quality product if it solved my issue.

I agree with the RCA's I have seen so many posts on alternator whine because they had the power wires near the rca's.

I agree with that, I think the Accord has some bolts under the seat that are supposedly good grounding points.

Have you tried testing each source separately? Each amp, rca's, speakers wires. This could help pinpoint where the ground loop could be coming from.

You said you had the gains set high? Did you set them with dmm, oscilloscope or by ear? Try turning the gains down a notch and see if the whine goes away.

Last thing: older pioneer decks had an issue with RCA ground fuzes blowing in the head unit. This post shows how to ground the rca's to the head unit with small wire.
How to Ground your H/U's rca's *pics* - Realm of Excursion
Power and rcas are on opposite sides of the car.
I've tried the shorting plugs on the rcas and I figured that since the noise stopped there, I didn't need to break it down any more. It has to be the HU or something even further up the line.
And well the seatbelt bolts are under the seat.. I guess I never really looked to see what other bolts were under there because using the seatbelt bolt is relatively common.
I set the gain's by ear. Basically I could tell that I could turn the volume up to the decks clipping point without clipping the amps.. So I turned it up a bit more. I know that if I turn the gain down the noise will decrease, but that's not an optimal way to fix it..
Lastly. As I said in my first post I have already grounded the rcas to the HU's case. This didn't have any noticeable affect. From what I've read, the 80PRS no longer has the pico fuse, but instead uses a different component that is pretty much just as susceptible to damage. Unfortunately I haven't found anything online about opening the deck up and fixing things in there.
 

·
Registered
Joined
·
104 Posts
Gains that are set really high can introduce hissing and noise in the system. I know my kicker zx700.5 will do that at really high gains. You say you can only hear it at low volumes, does it change pitches while accelerating (alternator whine) or does it just make a hissing sound that doesn't change when accelerating or turning the volume up? If you truely believe the sound is coming from the hu, try plugging up a speaker directly to the hu.

RCA wires can pick up interference from anything in the car. The reason people said to try rca's outside the car was to make sure that it wasn't some other wire in the car interfering with the system.

Do you have any other family vehicles that you could swap batteries with to test? When you said that the noise is only apparent with the alternator running, so when the car is off and keys are in you get no noise while hu and amp are powered?

I have heard that others have had problems with alpine amps causing noise problems. I have also seen people trouble shoot noise where they unplugged RCA's individually and found they can identify which amp, rca's or speakers are having the problem.
 

·
Registered
Joined
·
11,999 Posts
Any GLI's you recommend? I'd be willing to spend a bit more than $12 for a quality product if it solved my issue.
yes, but the $12 one will solve the problem and you only spent $12 if it didnt.

Look up jensen tranformers for good isolation xformers.
 

·
Premium Member
Joined
·
2,107 Posts
have you tried it with the hu out of the dash? you said you tried the shorting plugs but didn't indicate if you drove around with it. if the noise is gone with the hu unplugged it doesn't have to be the hu itself it could be something near the hu that's being inducted to it. I've had that happen to where when the hu was out of the dash no noise.
 

·
Registered
Joined
·
3,070 Posts
Oddly, I once put in an Optima Red Top in a car that had noise just because the battery in it had died on me. Noise gone. Put in a different battery that was newer but more normal (regular old Die Hard Silver) and known to be in good shape - no noise. Put the original battery in (now charged) - noise is back. Not expert enough to know why that happened.

More and more, with the cars that have variable output alternators, I'm getting noise issues. It's rare but nonetheless, for me, it's always a car with a variable output alternator that gets noise. Never have an issue with any others. No idea why.

My suggestion: time for a new car! ;)
 

·
Registered
Joined
·
41 Posts
Discussion Starter #15
Oddly, I once put in an Optima Red Top in a car that had noise just because the battery in it had died on me. Noise gone. Put in a different battery that was newer but more normal (regular old Die Hard Silver) and known to be in good shape - no noise. Put the original battery in (now charged) - noise is back. Not expert enough to know why that happened.

More and more, with the cars that have variable output alternators, I'm getting noise issues. It's rare but nonetheless, for me, it's always a car with a variable output alternator that gets noise. Never have an issue with any others. No idea why.

My suggestion: time for a new car! ;)
Interesting! See I think I've heard other people have the same results when replacing their battery, but Id like to know for sure that my battery is bad. And I like your suggestion haha. Maybe next summer.

have you tried it with the hu out of the dash? you said you tried the shorting plugs but didn't indicate if you drove around with it. if the noise is gone with the hu unplugged it doesn't have to be the hu itself it could be something near the hu that's being inducted to it. I've had that happen to where when the hu was out of the dash no noise.
I never thought of that.. But yeah, I've been trying it out of the dash as I worked on it so I don't think that that is the problem.

Gains that are set really high can introduce hissing and noise in the system. I know my kicker zx700.5 will do that at really high gains. You say you can only hear it at low volumes, does it change pitches while accelerating (alternator whine) or does it just make a hissing sound that doesn't change when accelerating or turning the volume up? If you truely believe the sound is coming from the hu, try plugging up a speaker directly to the hu.

RCA wires can pick up interference from anything in the car. The reason people said to try rca's outside the car was to make sure that it wasn't some other wire in the car interfering with the system.

Do you have any other family vehicles that you could swap batteries with to test? When you said that the noise is only apparent with the alternator running, so when the car is off and keys are in you get no noise while hu and amp are powered?

I have heard that others have had problems with alpine amps causing noise problems. I have also seen people trouble shoot noise where they unplugged RCA's individually and found they can identify which amp, rca's or speakers are having the problem.
Its definitely alternator whine. There is no hiss or static. It doesn't change relative to the HU volume. My guess is that if I did plug a speaker directly into the HU I wouldn't notice the noise because the speaker out has a much higher voltage signal than the rcas. In other words, higher signal to noise ratio. I might try finding another battery to swap, but none are readily available. I'd be very surprised if my alpine amp was the problem. It runs on a separate set of rcas and only powers the subwoofers.

I just ordered a GLI from PAC. It totally slipped my mind that I might need two since I have four channels, but oh well. Does it matter which end of the rca's I put it on? It'd be much easier for me to put it on the amplifier end of things..
 

·
Registered
Joined
·
104 Posts
I just ordered a GLI from PAC. It totally slipped my mind that I might need two since I have four channels, but oh well. Does it matter which end of the rca's I put it on? It'd be much easier for me to put it on the amplifier end of things..
Yup, I would try it near the amps first.
 

·
Premium Member
Joined
·
4,235 Posts
I think in Hondas during much of the 90s, the charge wire from the alternator is routed through the car and through the fuse box. I don't remember exactly, but I remember fixing noise when i was an installer by changing that configuration. Hmmm...lemme see if I can find something.
 

·
Premium Member
Joined
·
4,235 Posts
Yup. The charge wire runs through an electrical load detector which sends a signal to the ECM to adjust the idle when the alternator is under a load. Try running a wire directly from the alternator charge post to the battery. The load detector is in the fuse box under the hood.
 

·
Registered
Joined
·
104 Posts
Yup. The charge wire runs through an electrical load detector which sends a signal to the ECM to adjust the idle when the alternator is under a load. Try running a wire directly from the alternator charge post to the battery. The load detector is in the fuse box under the hood.
I believe he said he did the big 3. So would he have to disconnect the one running to the fuze box?
 

·
Registered
Joined
·
41 Posts
Discussion Starter #20
I believe he said he did the big 3. So would he have to disconnect the one running to the fuze box?
I did the big three, but I didn't touch anything over in the fuze box area. I just ran a wire from the positive post on the alternator to the positive on the battery.
 
1 - 20 of 28 Posts
Top