Bad Engine Whine only When i plug in my Sub

[Original_Ranger84]

Alright so as it is I have a 99 ranger, Pioneer Primier DEH 410UB headunit, Pioneer Primier 6x8 door speakers that are hooked up to an Alpine MRP F300 4 channel amplifier with Rockford Fosgate wires and RCA's. The system sounds fine with just that stuff hooked up ( a little bit of noise if the musics really quiet but nothing too bothering).

Anyways, I have a 12" Memphis Sub and a Dual amplifier with a scosche wiring kit that I had hooked up a while ago that worked just fine, but i tried hooking it back up and now every time i hook it up it Whines like a MOFO when the engines on. If I unplug just the RCA's it goes away, so i figured I'd switch the RCA's and it still made the noise. I Am hoping its not the Headunit or Amp. Is there anything else that could cause it to make the noise when I have it plugged in?

 

[509lifted]

first off make sure ur ground is good on ur amp then if it is make sure u have atleast 12 inches between ur rca's and power cable. and one thing dual makes the crappiest stuff on the market so u would be better off getting a different amp

 

[Thed]

Dude, Dual amps suck. Sorry to tell ya. A lot of their amps and HU's have a whining problem that have plagued them since as long as I have known.

But, before you go spend money on a new amp, check your ground. Make sure it is touching bare metal and not any paint. Also, make sure you run the RCA cables and the power cable on separate sides of the truck. If it still does not work, make sure that your head unit is grounded well (seeing a theme here?). As a last option, twist up your RCA cables to help block out some interference. A good thing to do is to tape one wnd to a power drill and keep one end tied down and not moving. That'll twist 'em up good 'n' quick.

If nothing else prevails, see if you can borrow someone else's amp and see if that has the same problem as your Dual.

 

[5speedin2.3]

My pioneer headunit does the same crap.
I had to buy a noise filter for the rca's on the sub.

 

[Original_Ranger84]

Well the dual amp has been through hell and back in my old truck and its lasted 6 years of hard abuse, I've actually never had a problem with my Dual audio equipment. but i tried it in someone elses truck and it didn't make the same noise so I am thinking its the headunit maybe? The Grounds are good, the power cables and the rca's are only close when they get to the amp otherwise they are far enough away from eachother.

 

[Original_Ranger84]

Alright so its definately either a grounding issue or the HU itself. I can plug in either the sub woofer RCA or the speaker amp RCA's and it doesn't make the noise except maybe a little bit but not both at the same time. So my theory is:

1. that the grounds i have are not good enough for the amps as they are both attached by seat bolts that i cleaned up so its metal to metal but they are both attached to the body which might not be grounded well enough for both in itself?

2. that the stereos ground is not good enough even though its connected to the factory stereo ground.

3 the thing about the RCA pre outs being crap on the Pioneer HU (which i am inclinde to believe at this point.) because i had the head unit powering the door speakers and the sub was hooked up and all was working fine, then i took the sub out and hooked up the door speakers to the alpine amp (not putting the sub back in at this point) and the rear preamp wasn't working so i had to either adjust the fader/balance to either full front or full rear for the speakers to put out anything but bass. I couldn't get them to work right no matter what. But when i hooked up the sub to the sub preamp output the rear speaker preamp started working like mormal and the buzzing started.

 

[5speedin2.3]

My alternator took a crap after submerging the front of my truck.

Anyways. The whine on mine is gone now.
Maybe it wasn't the cheap pioneer headunit after all.

 

[Original_Ranger84]

Hmm well my alternator is brand new and if it was bad i would think it would send the whine through either amp reguardless of how they are hooked up...