Hi:

I have a 2002 MCS and I just found a couple of nice thin amps with built in fans that fit in the boot recess perfectly. I am going to build a peg board cover so that they will be able to breath. The stereo sounds awesome with this set-up except for a slight engine whine. I fear it may be because I ran my RCA's and speaker wires along the driver side. It wasn't until I was hooking the amp power to the battery cable that I realized that that thick red wire was the main power cable for the car and it runs to the front right along side all of my audio cables. Is this what's most likely causing the whine? I really hope I don't need to relocate all that wiring. Since posts are better with pictures:

 

I have slight engine whine, and the RCAs run on the other side of the car.

It could be pick-up from the battery under the amps (try lifting them 6" or more).
It could be (most likely) a ground loop between the front of the car, where the stereo is connected to chassis, and the back, where the amps are connected to chassis.

 

Thanks, looks like relocating the wires will be my last resort. I may try putting a rubber mat between the battery and the amps. Maybe it will insulate it enough if that is the problem. I was also going to try a ground loop isolator. On a side note, I used peel and seal from Lowe's in the roofing section for sound dampening. Thinner than dynamat, but at $13 for a 25'x 4" roll it is a lot cheaper. I covered the whole boot area and battery box and it greatly reduced the magnaflow drone

 

If you do try a ground loop isolator and it works, please let me know - thanks

 

You can pick up a choke at an auto parts store to put on the rca's at the amp end.
A ground loop would be heard as low hum.
Does the sound change with engine speed - If yes then its alternator noise.
Do you have the polarity correct on both amps?
Do you have noise on both amps or just 1 - try switching the RCA's around if it only came out of 1 - if it changes amps when you switch the rca the problem is the head unit. If you switch RCA's and the noise still comes out of 1 amp the problem is with that amp.

 

Your ground wires are to long. They should be as short as possible. If possible I'd run the ground wire directly from the high amp througt the floor straight down and then Clean the metal of all the paint and primer, You could just use a flat head screw driver to remove the paint and primer. Then use two sheet metal screws to firmly hold the ground wire down.

The next solution that will more than likely work is, go to the local car audio store and purchase a RCA noise filter, I sell them in my store for about 20 bucks. All you have to do for most of them is ground 2 little wires to a screw on the CD player and just plug in the rca jacks...---------------> This is a really easy to do and will deffintly fix your problem.


PS: running you RCA jack on the opposite side of the car is the best way but not necessary. As some one who owns/ works for a car audio/ peformance store time doesn't often allow for the wires to be ran on opposite sides of the cars. Its normally a bad ground. Out of 100 cars with the wires run on the same side I'd have to say only 10 will have engine noise because of the powe wire. Hope that helps.

 

You can try a noise filter like this - if all the others checks are ok

 

Sounds like ground loop to me.

 

Wild guess, but I do know that for most people an iPod (not sure about other things) drawing power from the front cigarette lighter will cause an engine speed sensitive whine. Unplug the power thing from the lighter, and it goes away.

 

OKay, I'll try and answer these:

Yes the sound changes with accelaration.

I believe the polarity is correct on both amps. I have 4 guage wire going directly from the battery terminal to a fused link and then two 6 guage wires that connect to the pos connections on the amp and 2 6 gauge wires from the negative terminal to the ground connection on the amp.

As far as I can tell I have noise on one amp, but the other amp is for the sub only, so it is hard to tell. I have three RCA outputs on my HU. One is for the sub and the others are front and rear

 

Thanks, I have pretty short grounds, abouit two feet, but they are grounded to the negative terminal. Is that okay or should I ground it somewhere else?

 

You should deffintaly not have them grounded to the negative terminal. It should be a chassis ground with clean metal. Also the rule is the ground wire should be no longer than 2 feet. I have alot of customers that come in with grounds way to long or not connected right. Your pushing the limit on the ground wire length, Also you could use a piece of the 4 gauge to make a larger ground, this will help with the wine (possibly) and make your amp preform much better. Power cycle in a car flows from ground to power, so the ground wire is the most important. I just found that fact out about 2 months ago and I've been doing this for years. So I'm still learning too, so if you have any more questions feel free to ask away.

 

Thank you, I have some 4 gauge and it is even black so I will do that and post up the results

 

It is definately alternator noise because it changes with engine speed. Putting the amp right across the battery (not using chasis ground) essentially puts the amp right across the alternator when the car is running. Not good.
You should get better results when you move to a chasis ground instead of battery neg.

 

Well I did a couple of new chassis grounds with 4 guage wire and I still have the whine. It did sdeem to not be as loud. It may just be the placement of the amps. I need to find a rubber mat to put between the battery and the amps and see if that will shield them enough to stop the noise

 

It probally won't stop the noise, honestly I wouldn't waste my time with the mat unless your doing it for other reasons. If I were you I'd just give in a buy a noise filter as I'm sure it will stop all the whining. I'd go for the PAC Brand (there the best) there a little more money like 5 dollars or so but I've never had one not work at stopping the noise.

 

Before you isolate the amps with rubber...
Tell me about your head unit, where are you getting the power from for the head unit? Did you install it with the amps? Did you pull power from the Cig Lighter?

 

Thanks for all the help everyone, much appreciated. The HU is a Pioneer [FONT=Arial]Premier DEH-P7700MP 50Wx4 Single CD Head Unit. I used the wiring harness from Mikey that has the MFSW adapter on it. It was installed in Jan. Since it is using the wiring harness, it gets its power from the factory connection. I am not pulling power from the cig lighter, but i did hook up interior LED lights using the light power wire for the cig lighter[/FONT]

 

It is alternator noise, most likely through the power feed from the battery. You have a few choices, but 1 more thing to check.
Is your amp gain set all the way up to max? It should not be all the way up. To properly set amp gain you crank the head unit volume then slowly turn the amp gain up until you just start to hear distortion, then back it off a bit.
Otherwise:
1. Buy a noise filter for the power feed and/or rca's. The noise filter works best installed as close to the alternator as possible.
2. purchase some clamp on noise suppression ferrite filters (radio shack) and put them on each end of the amp power feeds and the audio feeds (rca) if you like.

I hope you get good results.

 

Thanks, I will adjust the amp levels tonight, the other things if needed will have to wait till the weekend

 

I just did the level adjustment and I still have the whine. I will try grounding the RCA's next. Thanks for the help everyone

 

It sounds like you are having similar issues to me. I found raising my amps 6" or so above the boot floor reduced most of the alternator whine I was experiencing. The problem was that it reduced the limited boot space even more. My plan is to relocate both amps to under the front seats and see if that removes the whine. I tried a PAC ground loop isolator to no avail. It actually increased the whine

I also tried ferrite clamps with no luck. I should know in a few weeks, when I have time, if relocating the amps fixes the issue.

 

So I bought a couple of these PAC SNI-1 RCA noise filters (from someone on eBay).
First thing is, they're designed/built backwards! I wanted to connect at the amp, so I wanted RCA sockets for the input (the cable coming from the head unit at the front of the car) and a short pigtail with RCA plugs to go into the amp connectors.
Well the PAC modules are designed to go at the head unit end, and the plug & socket are reversed

So step 1, take the glued together case apart, cut tracks, de-solder and re-solder wires, do a couple of links, and now the plug & socket are the "correct" way round (for me, anyway).


Now out to the car.
I have two pairs of RCAs going into the amp - one for the front left/right and one for the subs left/right. First step I disconnected the sub RCAs to get them out of the picture, turned down the head unit volume to zero, and turned up the amp gain to maximize the amount of engine whine.
With the RCAs connected to the amp, the whine is there. With the RCAs disconnected, the whine disappears - suggesting it is ground loop noise or wire pick-up, and not pickup into the amp from the battery.

So next I put the PAC filter in line between the RCAs coming from front of car, and amp input. Sadly there was not much difference - certainly not enough to go hooray (maybe there was none; it's hard to compare exactly when measuring by ear!)
So I guess that suggests cable pickup rather than ground loop issues.
BTW: I did turn up the head unit volume and could hear sound, so my modified PAC is working - it just doesn't help.


So now, back to original with no PAC filter.
But just for fun ... I have three sets of RCAs coming from the head unit, front l/r, rear l/r and sub l/r - the rear l/r set has never been used. So I connected that RCA pair feed into the amp, instead of the front l/r pair (and shifted the fade from full front to full rear).
Everythings working again now, and AMAZING there is much less engine whine!
It seems that even though the RCAs cable carries all three pairs in one core, the pickup from the "rear" pair is less than the pickup from the "front" pair. Wierd!


Not sure how all that might help other people - pickup might be in the RCA cable and not ground loop noise ... and I have a couple PAC noise filters if anyone wants to buy them! One is modified to swap the plug / socket connections

 

This morning I went out and lifted the amps vertical against the backs of the seats and still had the whine. After that I used a VW monster floor mat to insulate between the battery and the amps and still had whine. So if I do this:

" Now out to the car.
I have two pairs of RCAs going into the amp - one for the front left/right and one for the subs left/right. First step I disconnected the sub RCAs to get them out of the picture, turned down the head unit volume to zero, and turned up the amp gain to maximize the amount of engine whine.
With the RCAs connected to the amp, the whine is there. With the RCAs disconnected, the whine disappears - suggesting it is ground loop noise or wire pick-up, and not pickup into the amp from the battery."

I guess it will tell me where the source of the whine is and what to work on. I am thinking about going and having a custom enclosure built by a local shop, so I think the next step will be to see what they do. Once again thanks for all the help.

 

Fortunantly I don't have any amp whine after my install. I don't know why you are getting whine but here is what I did that may be different from yours.

1. amps mounted where rear seat used to be so I'm not over the battery.
2. power cables from CAP to battery + / chassi - are more than 2ft 4 guage.
3. Amp power from Monster 1 Farad CAP (8 guage to amps) 1 is 2 ft other is more than three.
4. Ground for Head, iPOD adapter and PAC SWI-ECL is the chassi - did this to get the SWI-ECL to work right, originally was using the harness ground and didn't notice any whine, but I cant remember if I even tested with the car running before changing it.
5. Coax runs up the hump in the middle of the car and so does the speed wire for the spearkers.
6. Used the middle of the road price wise red Monster coax cables (they are not grounded)
7. I cut off the factory harness and soldered on a universal 12 pin connector from radio shack (did the same for the harness for the new head). - I actually did this so that I could set it up to use the HU amp when I take the amps out for track days.

Pictures of my install are in my gallery. I hope you figure it out. The whine I got from the stock iPOD adapter was driving me nuts so I know how you feel.