interference

lately i have been working on a guys 2002 Ford F250 Crew Cab. The system consists of 2 JL12w7, 1 jl 1000/1, 1 jl 300/4 ran to JL ZR 650csi (front) and JL XR650cxi (rear) and the headunit is an Alpine iDA-X001. the system also consists of 2 deep cycle batterys one under the hood and the other used as secondary with a pac200 in between the two. it sounds great! only problem is there is a HIGH pitched whine whether the vehicle is on or off. and it does not change sound with the engine speed.

routes of correction i have taken include regrounding the 300/4 and Alpine H/U. Changing out the 300/4 with a 300/2 the customer had laying around. still same noise...Thinking that there may be some problem with the head unit i took it out of the f250 and put it in another vehicle with simmalar amp set up and no noise. im really stumped on this one. any idea is appreciated

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2007 Acura TSX
SQ setup in the works

Had a similar problem one time with JL comps. because the primary power lead was run close to the crossovers. Fire up the system and move the crossover closest to the power wire away from it. Good luck.

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There is no such thing as free installation!

thanks for the imput...i tried moving the crossovers further from the amps and no change...any other idea?

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2007 Acura TSX
SQ setup in the works

and just to add to that it is comming out of all 4 speakers

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2007 Acura TSX
SQ setup in the works

Have you tried grounding the rca's from the back of the HU? This was my exact problem on a pioneer unit. Try it and let me know what happens. Are you located off beach or atlantic?

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03 F150 on 24's
HU:Pioneer DVD5700
Frt:MC57
Subs:(12)S12L7
Amps:(3)KX2500.1's, MC-2004

when you say ground the RCAs do you mean ground it to the car or ground them to the radio? no actually im over in orange park

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2007 Acura TSX
SQ setup in the works

Yes, I believe he's referring to a quick cure to a common RCA problem. However, I'm not sure this is the problem in your situation since the HU worked fine in another vehicle.At any rate, if an RCA in the back of the vehicle touches a positive lead it can "burn" the ground trace in the HU. This problem can be fixed externally by wrapping a short(6" or so) wire around the outside(ground) portion of the RCA and then connect the other side of the wire to the chassis of the HU, your essentially bridging that burned trace back to the chassis.

This is a common cure for HU's that make your subs thud and rumble when there is no music playing.(lol, in fact the clarion indash dvd in my daily driver has this problem and instead of pullin the HU apart and soldering the trace i did a quickie fix with the wire trick.)

I doubt this is the problem but i remember a system quite a few years back I had a similar problem, it ended up being the fuel pump creating the high pitch interference. I moved the physical placement of the amplifier and vu wah lah

Have we tried turning the gain down on the amp till the noise goes away?

:::::UPDATE:::::

Finally got the noise out. it turns out that the customers RCAs were compromised when his system was stolen out of the vehicle. it also turns out after chaning the grounds we tried just grounding them to the same spot and it came out?  

NEW QUESTION...i have always heard that you shouldnt ground multiple amps to the same spot...but in this instance it worked for the better?? anyone have an opinion on that?

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2007 Acura TSX
SQ setup in the works

actually i remember reading in another post that it was better to ground in the same spot, as long as the ground screw could handle it. i'm guessing it has to do with all the power running through one path instead of spreading out throughout the vehicle (compramising the rca singnal) trying to find the shorts way to ground.