Engine Whine when air con is switched on.....

shabz34526 · 03-21-2009, 11:28 AM

Hi Guys,

I have just registered at mp3car.com. I hav an issue with my rear speakers giving a whine when i switch the A/C on. I have read through the various threads n posts on this issue and have done most of it.

I just got all wiring changed from the previous one to monster cables. However, the engine whine is still there.

Just to give you an idea of how it all started. Initially I was running a 2 x 12" Subs with a Westcoast custom Amp. I did not have any noise or whine. I decided to install a second Amp for the speakers when I changed em. There we go started the whine. After hours of switching wires I found out that it was the newly installed rear speakers that are giving this whine which increases on acceleration.

Based on findings from mp3car.com I moved all RCA cables to run via the leftside and power cables through the rightside. Grounded both Amps at the same place but the moment I switched the a/c on the whine is back and it is very annoying.

Please help...

shabz34526 · 03-30-2009, 01:29 AM

Hey guys .... anyone has any reply for me?

2k1Toaster · 03-30-2009, 01:48 AM

well this is a CarPC forum, not a general audio forum.

But sounds to me like you dont have sufficient guage power cable to your amps.

da_kooz · 03-30-2009, 03:24 AM

I agree that it is possible that your wiring might be inadequate. Also, your alternator may be taxed to capacity.

thewizard · 03-30-2009, 05:44 PM

It sounds like a ground loop to me. I bet that a ground loop isolator would get rid of the whine, but that is only a band aid fix. You need to find the source of the loop to fix it properly and permanently. Some amps are much more susceptible to this than others, so yes it is possible to get noise from one amp and not the other.

shabz34526 · 03-31-2009, 08:40 AM

Hey Guys,

Thank you all for you replies. I have a 10 gauge power cable to the first amp and a 4 gauge cable to the second one. I will have this changed to 10 gauge for both... I'm not sure if this is going to help in anyway..My ground loop isolater is on its way from the states. I will have that put in place when i get it. But yes, otherwise i have tried all the possible options, like changing the cables, separating RC cables n the power cables, grounding at the same place n stuff... but it seems to remain... So other than getting the ground loop isolator installed I cant think of anything else... may be u guys can suggest...

oh by the way... when i joined at mp3car.com n started runnin thru threads i did not notice the fact that this is carpc forum.. sowie abt that... was in a bit of hurry coz of the given situation n wanted help as quickly as poss..... next time ill def take care of the forum....

sectorz · 03-31-2009, 11:19 AM

I'm having the same problem. I have a minor popping sound I noticed in my subs when I adjusted the volume. After installing an amp to power the mids/highs I got alternator whine in the speakers. I'm going to try remedying this by disconnecting the head unit from it's current source and running a ground wire off the same location the amps are grounded to.

Check this out:
http://en.wikipedia.org/wiki/Ground_loop_(electricity)

2k1Toaster · 03-31-2009, 01:51 PM

10awg is smaller than 4awg.

And do you have 2 separate cables running all the way from amp to battery, or do you have 1 cable from the battery that is split somewhere?

shabz34526 · 04-01-2009, 03:55 PM

yes i have separate power cables running from the battery to each of the amps. the power cables r runnin through the left side n the rc through the right....

the only difference is tha 1 is a thick wire (4 gauge) and other thinner one (10 gauge). am not sure if this plays any role in the engine noise....

i have two pairs of HID xenonz, one 2 amp capacitor, one 800 watt amp, one 450 watt amp, the head unit, two subwoofers, all powered by a single battery..... i dont know if these would draw too much electricity from the battery that the second amp is not getting enough charge...

sectorz · 04-01-2009, 04:11 PM

Quote: Originally Posted by shabz34526

yes i have separate power cables running from the battery to each of the amps. the power cables r runnin through the left side n the rc through the right....

the only difference is tha 1 is a thick wire (4 gauge) and other thinner one (10 gauge). am not sure if this plays any role in the engine noise....

i have two pairs of HID xenonz, one 2 amp capacitor, one 800 watt amp, one 450 watt amp, the head unit, two subwoofers, all powered by a single battery..... i dont know if these would draw too much electricity from the battery that the second amp is not getting enough charge...

You have a capacitor? Wouldn't it be better then to locate the cap beside the amps in the back if you haven't already, run 4g wire directly to it, and then 4 or 10g wire from it to each of your amps instead of 2 separate runs? Then ground the cap's (-) with a short grounding cable and run the Amp grounds off it. Maybe you could use that 10G run you're no longer using to supply ground to the deck. That way everything's grounded at the same source.

thewizard · 04-01-2009, 06:43 PM

I am assuming that you mean 2 farad's on the cap, not amps? Also I don't mean to bust your bubble here, but that cap will do squat for your system. I run two amps in my system, a 4 channel 75x4 @ 4ohms and a huge bass amp that produces 3200 watts RMS, no cap in my system at all. I run a single battery with two runs of 0 gauge wire from the battery to distribution blocks in the back. From the blocks to the amps is also 0 gauge wire. I have absolutely no engine noise what so ever. I also have next to no voltage drop and my bass amp alone can draw 200 amps when the system is really cranked. A cap will not do what most people think that it will, as it will not give you a boost of extra power. All it will do is filter out some AC ripple and that is all. The SPL people will tell you, and keep in mind that these guys spend their lives testing their setups, SPL is always higher without a cap, it is simply another load on the system. Your larger wire, in your case the 4 gauge should run from the battery back to a distribution block, or in your case the cap (same difference as far as I am concerned). Your amps are fairly small so you could use your 10 gauge from the cap to the amps. Make sure your grounds are really good, not just so so. Make sure that the two amps are not touching each other as this can also cause noise. Sometimes even having an amp screwed down to metal can be the source of noise and the source of a ground loop which will cause noise.

shabz34526 · 04-02-2009, 10:34 AM

hey yall... thankz for all da help... am tryin all sorts of wierd stuff to get rid of this bloody noise....... not successful so far.....i have grounded everything... the noise has reduced but not completely gone...

merlin12volt · 04-02-2009, 10:55 AM

There are several things I would look into. Some of them have been gone over already, but I will give you my start to finish on how I would approach this. I have been installing custom car audio and electronics since 1996 so I have a little insight into this issue.

1. What type of car Head unit Amps wires, speakers used. Not looking to brand flame but certain companies are known for certain issues.

2. Check all wiring, make sure all grounds are as short as possible all grounded to together to a good piece of chassis metal with no paint around it. Look where your Headunit is grounded. Sometimes factory ground is not sufficient and using the metal structure of the dash isn't either.

3.check RCA's.
To do this, swap your rcas for sub amp with other amps. Does the whine move to those speakers? If so, bad rcas. If not un hook rca's from headunit and leave them lay. Still there? if so unhook from amps and check. If not issue is with headunit, either the ground for it is still bad or you are injecting noise to it from an external source. Cheap headunits are notorious for this and sometimes it is easier to make them a paper weight and buy a better unit.

If it is not the head unit and all the rcas are unhooked and you still get noise, issue lies with the amp and the wiring to it power/ground wise. Post more and some pictures if possible.

shabz34526 · 04-09-2009, 05:49 PM

hello everyone... thanks all for ur support n post..... jus a new issue that has come upnow... i hav two amp remote wires runnin frm the headunit to the amps... i grounded all at the same place.. here is my issue... the whine has increased.....it increases all the more if i hold the beam on......after all the hastle i managed to get more whine n ot reduc3e it.. n am so frustrated right nw...;-(i hav no clue as to what i need to try next....

shabz34526 · 04-09-2009, 05:55 PM

well the system is quite simple.... kenwood head unit... pioneer speakers... 1 x sony xplod n 1 x clarion woofers..... 1 x west coast customs amp 1 x JBL amp....RCA x 2 monster cables.....

all groundz r short except for the amp in the trunk......this is a bit long coz i ran the wire from the front seat to the trunk....

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