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Car Audio Installation - Tech Help with ALTERNATOR WHINE

dalexirtch

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Hi all,

I'm living a nightmare trying to chase down alternator whine in my system. I've been at it for a month. Please help me!

I am fairly sure its alternator whine. My symptoms are whine when car is running, starts immediately after ignition, whine pitch rises and falls with engine RPMs.

System Includes:
- Pioneer double din radio (https://www.amazon.com/dp/B07J5MQPH7?psc=1&ref=ppx_yo2ov_dt_b_product_details)
- PAC RP4.2-TY11 (https://www.crutchfield.com/S-Aghr6...BNKInfypcJsZ451bgwQR2orIKycDJlXYaArPYEALw_wcB)
- JL audio XD400/4 Amplifier (https://creativeaudio.net/xd400-4-k...PlVZ3_k9Tp7bV-2zepykDVErB6aONCZYaAgTvEALw_wcB)
- JBL Basspro Nano SL2 (https://www.amazon.com/JBL-Basspro-SL2-Powered-subwoofer/dp/B08CK6TNBT)
- Twisted pair RCA cables (https://www.amazon.com/dp/B07Y5S4PMS?ref=ppx_yo2ov_dt_b_product_details&th=1)
- Amazon basics speaker wire (https://www.amazon.com/dp/B006LW0WDQ?ref=ppx_yo2ov_dt_b_product_details&th=1)

I am still using factory speakers - the speaker wires coming off the AMP go to the original speaker leads at the harness where the door hinge is. To rephrase, the speaker wire I have at the amp does not go into the doors and directly to speakers, but rather to the original speaker leads coming from a harness at the door hinges.

I did not have any whine when I installed my head unit. The problem only started after adding the powered subwoofer and amplifier, which I did together.

When amplifier RCAs are unplugged at the head unit the whine goes away.
When amplifier RCAs are unplugged at the AMP the whine goes away,
When powered subwoofer power and ground is unplugged the whine goes away
Amp gains are set med-low


Trouble Shooting So Far:
- replaced shielded Kicker RCAs with current twisted pair (no change)
- replaced cheap CTsounds amp with current JL XD amp (no change)
- negative leads from head unit negative lead to RCA shells when using kicker RCAs (reduces whine by 50% - but this did not work with the new twisted pair)
- 16awg from battery negative terminal to head unit (tried connecting to both HU ground lead as well as HU metal casing - no change)
- 16awg from head unit ground lead to amplifier ground port (reduces whine by 50%)
- head unit ground lead to chassis pillar behind dash (no change)
- moved both powered sub and amp grounds to new locations (no change)
- moved both powered sub and amp grounds to the same location (no change)
- ground loop isolators tried at head unit and at amplifier (no change)


What others have recommended that I have not done:
- "add a new 4-0g ground to the negative terminal and down to the chassis of the car. We often pull more current with the power wire, but rarely reinforce the ground wire at the battery."
- replace alternator
- I went to a car audio shop and we went through everything. The best advice the owner had to give was that years ago he did an install on a Corvette and it had the same alternator whine. They chased it down forever and finally fixed it by putting some sort of power filter on the alternator. I don't know what this device is called, or what it looks like.







 
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Keith_W

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Welcome to ASR. I suspect this is the car audio equivalent of a ground loop? We are mostly home audio guys here, and the normal solution is to lift the ground. I realize that's not possible in a car. Hopefully someone will come along and propose a solution for you. Otherwise, try a car audio forum.
 

amirm

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- 16awg from head unit ground lead to amplifier ground port (reduces whine by 50%)
Even if temporary, make sure all audio gear is powered from the same ground point. Don't use the chassis for this. Or have them grounded in different spots. 16 gauge wire is also too thin. Should use at least 10 gauge. Assuming you can do this safely, and the cabling is fused, you can power the whole setup temporary from battery terminals just to be sure.

Another thing is to make sure all the wiring to the alternator is extremely tight. Tug all the cables that are bolted to it. There should be zero movement. Just to be sure, tighten the nuts. Do the same to wherever the cabling from the alternator goes. Ditto for cabling to battery terminal.
 

Punter

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Many years ago, a colleague of mine from technical college worked at an auto sound business doing installs and repairs. They had a particularly interesting job come in where the alternator was apparently inducing noise into the audio system. After a lot of diagnosis and swapping out parts, the problem persisted. In the end, it turned out to be cracks on the drive belt for the alternator which were allowing tiny static discharges which got picked up and amplified by the audio equipment. Not saying this is your issue, just an interesting phenomena :)
 

DVDdoug

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With more amplifiers you've got more gain so any noise gets amplified, and you've got more opportunities for ground loops.

When powered subwoofer power and ground is unplugged the whine goes away
Is it gone when you unplug the RCA, and just leave the power?

Maybe a ground isolator (transformer) on the sub amplifier will help. Generally, I'd try to avoid transformers because sometimes they don't have "full" frequency response, but... It should be OK for the subwoofer, and even in the main channels it's probably preferable to whine.
 

Ruhled

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It can sometimes also be the ignition system when you get rpm dependant noise. Remove the serpentine belt for a couple of minutes and verify the noise doesn't persist. Don't run too long like this though because most engines' water pumps are also driven via the serpentine.
 

effj

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I had possibly the same problem years ago with a 2003 Nissan Sentra that I no longer own. I think the issue is that the line-level (relatively low voltage) RCA cables pick up noise as the signal travels, and the external amplifier then amplifies the noise along with the desired sound.

(1) The simplest solution might be to use an amp with speaker-level input and feed the speaker-level signal over speaker wire and avoid line-level preamp feed all together.

(2) If continuing with line-level signal, it might help if you’re not already doing it is to colocate the amp as close to the head unit as possible, make sure their two grounds are shared (using a distribution block, for example), and use RCA cables that are very short.

(3) and (4): I have not had the problem (or external amps for that matter) in other cars since my Sentra, but I resolved to take drastic measures in the future if I revisit having an aftermarket amp. Two additional, potential alternatives are to use either TOSLINK or balanced connections for transmitting the preamp signal, options which virtually no car stereo equipment supports natively. If either option is even viable or even fixes your problem, it might require signal converters (e.g. ADC and DAC) since as I implied head units and amps don’t typically support these things natively. Definitely follow @amirm ‘s, others’ suggestions, (1), or (2) first, as these last two ideas are largely hypothetical.
 
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Haflermichi

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You should try ferrite chokes on the power leads.
This is just one sellers offering. There are dozens of combinations. All are inexpensive to try out.
Ham radio operators have been using them for decades to deal with alternator noise in mobile installs.
 

OldHvyMec

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OK, let me understand what an alternator whine is? The noise is coming from speakers or a physical whine from a loaded alternator?

EX: Hooking up jumpers cables to a DEAD battery. That ark is the difference between the two batteries. That ARK can cause ignition.

The noise you are likely hearing is the difference in the two different amps, sub vs headset.

The gain needs to be turned down on the sub amp. You always test with alligator clips/ test leads and have a dozen handy. New batteries
in the DMM.

I want you to measure the difference in any ground wire going to ground that changes the noise. Measure DC voltage.

That difference is your speaker noise! The higher the sensitivity of the speaker and adding unneeded gain will exacerbate the situation.

You need a filter just like any other electrical noise unless it is induced by routing or crappy cabling. That can be sorted if you're careful
and pay attention. Follow the rules, loose wire don't work and a key to finding noise in any vehicle is being aware of the yo yo affect.

In other words as you move wiring the sound changes pitch or YO YOs.

If you rev the engine and the whine increases in speed at the speaker, what is that telling YOU? Is the noise coming from the sub or the
main speakers? No matter where it is heard the voltage supply to the new amp vs the difference to the head set is the noise. If the reving
increases it still a filter and the fix is a filter.

Do you understand? DC in a car does not have a neutral. TWO wire, not three. The only way to clean up noise is to match DC voltage
differences between chassis, firewall, frame and engine/alternator. In the case of amps the head set is at battery voltage and the sub
amp is likely lower.

I use SOOW 4/4 (no uninsulated wires). .9999 domestic, a cap bank and if needed an extra isolated battery.

So we are clear, a BAD or leaking high tension lead with no shielding is VERY noisy. Solid core ignition wires are easily found with a
transistor radio or a dark garage. I don't recommend using your hands and if you do use the back not the front of your hand.

A filter on the 12dc power lead to your new amp is the issue, most likely. Turn down the gain. Mead makes great tools to set the gain properly.
Check for voltage differences and use a filter to fix the problem. It is matching the voltage on the DC you can verify it if you like and also
gage how affective the match is. You can make a filter too.

I'm saying this to be kind, use heavy pure copper wire for all the wiring. NO aluminum anything, especially RCAs. The 16 gage is WAY to small
for any sub. Factory wiring is fine for factory units. Sub wiring is heavier, Period.

It's been a while since I retired but I'm sure there is a mechanic or two that can help sort this out. I hope I've given you some added
advice to the good advice already supplied. KEEP STUFF TIGHT. Keep stuff tidy in cars.

I hate the damn things. I served my gas apprenticeship in one of the last Rambler/Studebaker service centers. Then to Marine and stationary
diesel. Then to Cat, JD, Detroit, Cummins, Perkins, Deutz, for Linkbelt, Bauer, Kleem, Cat, Hyundai, Kobelco.

Drilling, Tie back, anchor drilling, trenching, tunnel boring, slurry walls, pressure columns. Fun $hit! Except fixing it in 2 foot deep
grout 1/2 way over the tracks in -10 to 120 degree F weather. I hate concrete and grout. If it wasn't freezing in Labrador it was burning
up in Panama or the Philippines.

My back hurts thinking about it, I need to calm down and feed the chickens.

Oh, Regards, happy hunting!
 

effj

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My first reply summarized a few suggestions, so in this one I’ll try to elaborate on the first suggestion.

According to Crutchfield (https://www.crutchfield.com/S-QwG7hKxOOlI/p_136XD4004/JL-Audio-XD400-4.html) as well as the JL Audio owner’s manual (https://pdf.crutchfieldonline.com/ImageBank/v20100707123900/Manuals/136/136XD4004.PDF), your JL Audio amp supports a speaker-level input signal (see Input Voltage Range on page 6 of the owner’s manual).

The manual also says you shouldn’t need a line-level converter unless “you find that the output cannot be reduced sufficiently.” I think this means it should work with the equipment you have as long as the Pioneer volume control is usable and the system isn’t too loud.

I recommend this approach as the JL Audio amp seems specifically suited for using the speaker-level signal from your radio. There are installer instructions in Appendix A on page 14 for setting the output level.

As far as the subwoofer input, you might be able to continue using the line-level signal.

If you are able to follow the approach outlined here, let us know if it fixes your problem.
 

Timcognito

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Unplug the alternater but let spin when running the engine, you may have an RFI problem.
 
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