sound system issues (bad ground maybe?)

[etlsport]

so i just put in a new head unit/upgraded all my speakers/added an amp in the VX and tested it, and it seemed to work great, but as soon as i started her up, i got a nasty whine coming from the speakers that gets louder as the engine gets strained. im guessing that its a ground issue, but i dont even know where to start checking grounds, if anyone has suggestions about where to start/other possible issues please help before i start taking unnecessary peices of the vx apart... only get the whine when the vx is running, sounds crystal clear when its not.. i might also be losing bass when its running.. but not 100% about that (i dont have subs.. see setup)

the setup:

head unit powered by stock power to head unit, split to give power to monitor, used stock head unit ground to ground the main ground and the 'brake' ground (so itll play dvds when the parking brake is off) and remote turn on to amp, no speakers hooked up to the head unit, RCAs out of the head unit (2 pair) go to the amp located under the drivers seat, 5ga power input, 4ga ground to bolt holding drivers seat down, all speakers have been replaced and new wires run to all of them

my RCAs come down next to eachtother down the center console and under the seat right near the seat belt buckle, power for the amp comes on the other side of the drivers seat

there is a moderately sized coil of RCA wire behind the dash because i got 15' wires thinking i was going to mount the amp back with the spare tire

sorry thats a lot of stuff.. but its a big project and i want to be done with it!

[WILLY]

I Think U Got A Defective Head Unit Or Defective Amp Or Just A Poopy One Posibly That Is Picking Up Interference From Ur Altinator. Ur Amp Hooked Directly To The Battery I Assume.

[WILLY]

Also I Would Change Ur Rca's To A Shorter Length,i Have Run Into Issues With Long Rca's B-4 And Fixed It With Shorter Ones,that Might B A Good Place To Start.

[biju]

i'd try the following:

1) Separate the power for monitor and head unit (HU) with upgraded lines directly to the battery (w/ fuse, etc.)

2) Reduce the length of RCA's and pay attention to the signal direction for the cables (my monsters were directional, providing arrows to indicate which end was for the HU and which end was for the amps...).

3) Change the ground for the HU. I wouldn't use the stock harness for that. Behind your HU there's a threaded bolt welded to the firewall (w/ nut). Use a dremmel and expose metal. Ground to that nut/bolt.

Steps 2 & 3 greatly reduced my alternator whine in my own setup.

Best of luck.

-biju.

[kpaske]

My aftermarket head unit is powered through the stock harness and I haven't had any issues, but the box is also grounded to the chassis with an external ground (in other words, there is a ground wire coming from the HU to a bolt in the mounting frame). Many headunits ground the box through the mounting bolts, so you should make sure that is a good metal on metal connection if that applies to you.

Also double check the ground on your amp. The seat brackets are painted and don't fit exactly flush. Make sure your ground is making a good metal-on-metal contact - use sandpaper to make sure both surfaces are clean and bare.

Also consider where your speaker wires are running - that wire is usually unshielded and susceptable to interference, particularly from the power lines.

If I checked both the grounds to my HU and the ground to my amp and was still having big interference problems, I would probably pull out the seats and carpet and fire up the radio with most of the wires exposed - that way you could move them around to see if the whine goes away. I normally like to do this before I put my interior back together just because it's a lot of work if you have to pull everything back out again.

[MZ-N10]

try pullin teh rca from the hu. if theres no wine after u pull the rca, the hu or rca r the problem. if there is still a wine then its ur amp or grounding.

[etlsport]

thanks for all the advice! seems like the easiest place to start will be with the amp ground under the drivers seat... themore i think about it the more im thinking it shouldnt be the head unit wiring causing the whine, i have the ground wire for it passing through a noise filter, but i didnt think about it grounding itself to the truck via the mounting screws, the exterior casing of the HU is copper, so that would make sense if that helped in the grounding.

biju, how did you get your head unit wired directly to the battery and still work with the ignition?

will update when i get in there and figure it out

[morgan-tec]

A good rule to follow is never use a stock ground. Also ground as many items to one place as possible. This reduces the # of ground contacts you have on the body which will reduce noise. I have my HU, four video monitors, a video amp, and my rear view camera all grounded to the same spot behind the dash. I have zero noise. Also check the amp ground that it is solidly contacting bare metal. What quality RCAs did you get? Just a suggestion that if you went with the inexpensive ones then you will have noise. The better they are the more they cost, mine were more than all the rest or the cabling in the truck and they were worth every penny.

[etlsport]

ok, i went in, regrounded the amp which didnt help anything , but thats OK it needed to be done anyway, was going to reground the head unit and monitor but then decided i want to swap their position, id rather have the monitor up high and the dvd player down low to improve the angle on the monitor (it will only go straight vertical if its mounted in the cd changer slot becuase of the slope of the dash) so ill reground them during the move... picked up some 10' twisted pair RCAs made to reduce noise, theyve got a 3rd wire on them, which im assuming is ground, do i need to do anything special to ground that properly? do i ground both ends? this is the first time ive really done a 'high end' installation so cheapie RCAs usually do just fine

thanks guys!

oh yeah, and i also checked where my speaker wires are running, only the fronts are near anything that would give me trouble (drivers door runs for about 2 ft with the power wire and pass. door infront of the TOD computer), looks like the main problem is RCAs

[etlsport]

DONE

put the dash back together, cd player in the lower slot, monitor in the upper

no more whine either! new RCAs helped some, new ground helped some (thanks biju) then i added an inline noise filter in the power to the HU and that seemed to get rid of the rest, during heavy acceleration its just barely audible, not at all when theres music playing

[MZ-N10]

i think the 3rd wire is for ur amp power signal, but if it works for u gj

[etlsport]

yeah, after doing some more research i found out they were for remote turn on, so i just taped them off, the upgraded wires definately made a difference though