Getting rid of Alternator Whine

TXSpeedDemon

Hey guys,

I finished installing my speakers and sub last weekend and am getting some pretty bad alternator whine now. Could use some advice on getting rid of it.

Few questions:

If I disconnect my rca cables from the amp and still hear the whine then the problem is most likely my amp grounding, correct?

I'm assuming I would still hear the whine if this was the culprit cause the amp would still send that sound to the speakers even if the amp is not getting any signals from the headunit. I think this is the problem cause I tried reversing a power distribution block to run all my ground wires (3) into one big wire and into one grounding spot. The line is now pretty long too, at least 18-24 inches.

If I disconnect my rca cables and do not hear the whine then the problem is most likely the power cord being placed too close to the rca wires, correct?

Power line is currently run down right side of passenger footwell behind seat and over to center column where it passes into the trunk. RCA cables are run down center column entire length. So while they don't run next to each other, they do cross over each other for about 1 inch.

Could the problem be the power wire running down the passenger footwell, and the passenger side speaker wires running down the kick panel (about 4-6 inches apart). If so, would I still hear the whine in the driver's side speakers?

Any other suggestions on what could cause it?

Thanks for the help/advice.

6spd

is this a noise from the alternator itself? or a noise from the speakers? sounds like interference from what you describe rather than the alternator whining. The alternator shouldnt whine unless its struggling because its bad or because of a weak battery.

__________________
-Jay- jonathanjamesphotographer.com

speedfreak28

It is most likely a ground issue. if you use quality shielded RCA's you wouldnt get interference even if the power wire was on the same side. It is however a good idea to run them on opposite sides just in case. crossing them is fine but try to do it at a 90 degree angle. What kind of head unit do you have? That could also play into the issue. If you dont mind posting a pic of your ground that would help.

vipor

Ground issue is definitely the problem.

- Make sure your amp is grounded well. Use a locking star washer and clear anything that isn't raw metal with a wire brush.

- Return Ground. Run a small wire (20-ish gauge, same as remote turn on lead or similar) and connect the ground of the radio and the amp together. You can land the wire either on the (-) terminal of the amp or use a ring terminal and go to the body of the car where you grounded the amp.
If you want to test this theory you can just run the wire through the middle of your car and hold it to the amp ground and the chassis of the radio. I've had good luck with this practice in the past and make it a habit on any amp install I do, regardless of whether it's a speaker or sub amp.

The shielded RCA's speedfreek is talking about would do the same thing, but would also shield the RCA's from the power wire if you did happen to run them down the same side. 18" gap is the minimum recommended spacing from power to signal wires, and yes, always try to cross at 90º angles.

__________________

2009 NISMO # 0193 | QAB | Albums! | 05.04.10 (Dynojet) 291.94hp/248.28tq
Oil Cooler (DIY) | Custom Headlights | GTSPEC Braces | F.I. Long Tube Headers

370Zsteve

I think you can also install a capacitor on the power line to eliminate alternator whine?

__________________
SOLD MY Z MARCH 2018 - another Core OG moves on - new ride 2019 Z Corvette Grand Sport - no mods necessary but already have eyes on HFC and intakes LOL IT NEVER ENDS.

vipor

That can work, but it's the more expensive route. Better to try the other ones first. Good fallback though, and if it's a sub amp then it can help with dimming lights.

__________________

2009 NISMO # 0193 | QAB | Albums! | 05.04.10 (Dynojet) 291.94hp/248.28tq
Oil Cooler (DIY) | Custom Headlights | GTSPEC Braces | F.I. Long Tube Headers

bigaudiofanat

Installing a cap will not help get rid of an alt noise problem if the grounds are the issue. Change your grounding point and make sure to sand it down to bare metal.

__________________
Need help with car audio or electronics? Let me know!! Need Help Let Me Know
Direct email address reimermatt@gmail.com
Owner of: Dynamic Mobile Audio Follow me below
https://www.facebook.com/Dynamicmobileaudio/

TXSpeedDemon

Thanks a lot for the feedback guys, much appreciated.

The noise is coming through the speakers, and changes pitch as I press the gas pedal.

All the wiring is from this kit: Rockford Fosgate RFK4D 4-gauge dual amplifier complete wiring kit at Crutchfield.com
I assumed the RCAs would be sufficient, but if these aren't good ones I'm open to recommendations.

I do think it's a grounding issue. I had stupidly covered all my grounding points with my sound deadening material and only had 2 bolts in view (directly behind center column in back small space of trunk) so have everything running to that single point. 3 8-gauge grounding cables running into a distributor and a 4-gauge cable running out and to the grounding point. I also left the 4 gauge full length in case I messed it up and had to rerun it someplace else - so it's about 3 ft long!!!!

Tonight I'll pull out the box and remove some of the sound deadening materials to expose a closer grounding point and cut all the wires to exact lengths (without using the 3-1 distributor) and see if that helps.

Headunit is an Eclipse AVN6620 with bluetooth, gps, rear camera and ipod adapters. The bluetooth is the only one placed behind the headunit, the rest are all mounted under the pass seat.

Thanks again for the tips guys, I'm DYING to get the car back on the road. It's been sitting in the garage for 7 weeks while I painted my wheels and stripped the interior for the sound deadening install. Hopefully I'll be cruising again by tomorrow afternoon

speedfreak28

thats definately a ground issue, Make sure the ground is attached to a bare metal contact point. What else do you have grounded to that point?

TXSpeedDemon

All fixed today, thanks again for the help.

I regrounded the amp powering the speakers with a single 8-gauge line to the same point most of the other guys here have and the whine went away completely.

I then regrounded the amp powering my subs with dual 8-guage lines to the same point, and changed the speaker wiring from 16 to 12 guage and OH MY GOD they hit 10Xs as loud and are CLEAN! At 50% gain my girlfriend heard it on the third floor of her condo and I was rattling her garage door in it's frame! I'm very happy now.

BTW, in case you're wondering I have 2 Boston Acoustics G5 10-44 Subs, wired at 2 Oms powered by a Boston Acoustics GT 2300 Amp with a 500 wt load to each sub. It's major overkill for this car but I love it

Speakers are Infinity Kappa Perfect 6.1 components powered by a Boston Acoustics GT125 amp putting out 125 wt RMS to each crossover. I would recommend a different speaker set up only cause the tweeters are dome and so I had to make a custom bracket to get them to fit in the stock location. But if you don't mind doing that they are great too. Crystal clear all the way up to volumes which make your ears bleed.

Liquid_G

TXSpeedDemon, what grounding point did you use, I tried searching for what most guys have done but have not found it.. I have a tiny bit of whine that I need to get rid of also.

__________________

GalletGun

bump? what is this mysterious great grounding location?

I just installed a new system and have a constant hissssss and alternator whine when rpm changes. Both of which go away when I turn the headunit off (amplifier turns off too). Pic is where I grounded my amp. Is this a newb ground attempt? I didnt sand or anything.

Attached Images

IMG_20140105_133308.jpg (482.5 KB, 25 views)

GalletGun

I figured it out. After relocating ground to a different location andnsanding down the metal it had no effect on the hiss and whine. I noticed the gain on my amp was at 3/4 max. I turned the gain down all the way to zero and everythimg is now whisper quiet. No more hiss or whine.

Ofcourse I have to turn up the volume higher now to get "loud" but on the Pioneer 4600 the volume seems like it goes on forever. With the gain all the down at a certain volume I would notice distortion but it was way beyond anybodies listening threshold. I wonder why anyone would even need to turn up the gain? Should I turn it up a little bit? Sound quality doesnt seem effected.

RonRizz

The gain on your amp is used to match input voltage from your source unit. It needs to be set to allow your amplifier to work at its best. If your Source is putting out 4 volts, thats where your amp gain needs to be.
There are a few different methods for setting your gain, The least favorable of which is by ear. Look into setting it with a multimeter, your easiest option.

__________________
P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

SouthArk370Z

As per RonRizz you will get the best sound when levels are matched but it sounds like you're in the ballpark. If you are getting enough volume and distortion is low, it may not be worth messing with. Depends on how picky you are.

__________________
Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub
Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma