Yesterday arvo i ran the new RCA lead through to my 2-channel amp so i could get my sound system up and running with the new boot install.

before we get any further in, i''l give you a bit of a run down of my system:
clarion MAX386VD head unit
Kenwood KAC9003(i think 3)D mono block powering
Kenwood 12"sub
Clarion APA-250 2 - channel amp powering
Alpine SPS-171A splits

i have found though i now have heaps of alternator whine through the system, coming through the front speakers. (its so bad its easier to drive without any music at all)

I used to get a tiny bit of whine through the system, but nothing really all that bad.

in doing the new boot install, i made significantly more effort this time to not let any power and speaker leads cross. I also changed the headunit from an old pioneer mp3 one. The old headunit only had one preout, so the clarion was wired through the monoblock's preout, the new headunit has separate preouts.

Has anyone got any suggestions on what i should be trying to look at? My plan of attack is:
Change the RCA lead
Test with a borrowed amp (i have a feeling that the clarion was possibly on borrowed time anyway)

and the plot gets thicker...

so over lunch today at work i decided to have a crack at swapping rca leads and the like, see if i could get any joy out of it. i turned the car on, it whined like hell. but then i popped the boot open with the engine running (obviously) and the whine stopped. i opened the door and it came back.

i spend about 15 minutes trying different combos of opening the boot and opening the door and it was consistent.

wtf does that mean?



something to do with opening the boot stops it from whining, and something to do with opening the doors makes it start again. just opening and closing the doors on its own doesnt make any difference.

I tried opening and clsing the boot when i was outside the car, and if the boot was open it would stop, closed it would start again??

mesa confuddled!!

Not real sure on this one problem but I had a Vulva in at work which had severe static and alternator noise and cleaned all the earths and put an earth strap on the bonnet and on the boot and that fixed it.And a bigger earth from the headunit to the battery negative [forgot that one.Hope this helps.Kevman

wooo! sorted!

turned out there was just WAY to much gain on the amp. poor thing was probly about to explode, lucky i didnt push through it!

also, the whole correlation to the boot lid theory died in the a*** when i tried it again yesterday morning and it did nothing. *shrugs* dunno what was going on there

Just induced noise by the sounds of things - too much current being drawn by the amp was enough to interfer with the RCA signals....

Could be related to the ground locations, conditions, surface area depedning how they are terminated, cable sizes, earth strap, quality of signal cables, signal cable location vs power and ground cables etc etc.

With the gains set in the factory default locations on the amplifier if you give her some volume does the noise come back regardless of doors or boot being open ? as turning down the gains will only mask the problem - its still there youve merely reduced the emittance of the noise....

sorry big kev, thanks for your reply, i didnt get a chance to post anything back over the weekend.

it seems that my problem might be a bit more serious than i first thought. over the last few days the noise has been slowly getting louder again. but it seems to be more in the right channel than the left.

i have also noticed over some bumps and things it might go away for a while then come back.

i am almost starting to think that possibly the amp could be on the way out.

next weekend (i wont get a chance until then), i will go through and check the amps groundings, check the crossovers are all nice and tight. is there anything else i would want to be looking at?


the ground hasnt changed from the old set up. the rca leads are not the best (part of those aerpro kits) but they are the same ones i used to use with no problems. the power and speaker cables dont cross.


unfortunatly i dont know what the "factory" gain levels are... i've had these amps for a while now but yes, as above, the nosie is still there now. its really got me confused.

Never fun trying to eliminate noise - its like tracking down all those damn rattles! Sort one and then another creeps up somewhere else...grr!

The factory gains depending whether or not your amps have the physical switches should all be set to 0db. Remove all EQs pretty much setting the headunit and amp configurations back to defaults.

Disconnect your batt, disconnect each ground and file any paint etc away ensure theres okenty of service area in contact with your ground terminal/block etc. (Most import is the battery negative to chasis connection and i'd disconnect and clean up your engine ground/earth strap).

Hopefully all your ground cables are shorter than your power cables and of equal or thicker guage.

SO if signal and power/ground cables do not cross do they run relatively close or opposite sides of the car....?

If you really wanna rule out the amp as the underlying cause have you got a mate happy to lend you an amp to test?

Off hand do all your ground come to a common point or area....is your battery and the factory location and just the amp grounded in the rear of the car? Does the battery ground connection or amplifier share a ground point with any other electrical component?

they run down opposite sides of the car, but now you mention, they do get very close in one part (when they go around the boot false floor frame). maybe that'll be a good area to have a closer look at.

yup. 4ga to a d block into 8ga for power, then 8ga into d block to 4ga for ground

as above, yeah, the two amps are grounded via a d block. they ground to the same bolt as the right hand side tail light. battery is in the factory spot.

nah, all my mates are C**k!

i had already sanded down the earth point for the amps themselves, but will re-check it. i will also have a look at the chassis earth strap.

thanks

yeah, i know

So any closer nicco to finding the cause? In the previous post its still no too big a deal if the sgnal and power/ground cables do come close the idea though is dont run them parrallel in close viscingity if they need to cross one another try to make it a qucik perpendicualr intersection that way any induced cross talk will be minimal...

I could suggest a noise supressor but they do only mask the issue and are really only ever a last resort..

May need to ask if a local audio shop can take a look over it one day if they have the time(may do it for free if you leave it with them for the day to look at between jobs)..to see if they can narrow down the cause and offer a solution....if they straight away to nosie suppressors i'd be hesitent they actually have a solid understanding of what they're talking about

Cheers
Kev

no unforunately, i ran out of time over the weekend. and this weekend is my uni graduation, so probly wont get time then either. lol

by the way, thanks for all your help so far, its definitely appreciated. I will post up here once i have something substantial to work with.

okay, i hadnt forgotten about this kev, i have just been damn busy!

got in today and cleaned up all the ground points in the whole system and it hasnt made any difference.

the whine has also been getting worse over the last few weeks and now it is just about un-bearable. it seems to have two parts to it at well (strange as that may be). it has a quiet whine which is there all the time, and it also has a loud one which comes and goes with no apparent connection to anything.

The quiet whine seems to be coming from just one channel, but the loud one is from both sides and also physically distorts the sound as well.

do you have any suggestions as to where i should be looking next?

cheers,
nic

so for anyone who is interested, i managed to find and fix the problem last weekend.

turned out that the where rca inputs into the amp were soldered onto the circuit board had become dry. i just pumped a bit more solder into the join and she's sweet as!

makes me happy that it ended up only being a 20minute fix not a whole new amp.

thanks for all your help once again big kev.

cheers

Had to go searching for this one thinking I wonder how nicco got on glad to hear it was such a simple resolution - but jeez what a pain.

Noise can sadly be induced from so many factors and I wouldnt have even thought it could be the internal RCA connections themselves.

Just glad to hear you didnt go through the process of replacing amps etc before a bucks worth of solder