Getting to the bottom of my alt whine

[POLKAT 10+ year member]

Hey all,

I have searched around and looked in countless "alt whine" threads on here and other forums but I have yet to find someone that had my specific problem. I have an 880prs and I am putting an active setup together. I have 3 amps. My sub and tweeter amp are in the back of my Trailblazer in a carpeted storage compartment and my mid amp is beneath front passenger seat. I have been running my stock speakers from my mid amp until my Exclusives come in. Everything sounded good (as well as stock speakers can) and I decided I might as well hook my tweeters up. That is when the whine began.

I am getting an alt whine from only my tweeter amp. The sub amp could be picking up the whine as well but since is crossed over so low its possibly filtering it out.

What is confusing me is my mids have no whine at all and I thought that if I had a ground loop that it would be present in the mids as welll.

The sub amp and the tweeter amp share the same ground. I drilled a hole in the floor, sanded the paint away and grounded them to a bolt at that point. My mid amp is grounded to one of the seat bolts where I also sanded the paint away.

The hu is grounded to an unpainted bolted area behind the dash that connects to the firewall.

Since there is no whine from the mid amp does that mean I can safely say that the hu is not the culprit?

• I removed the fuses for the other two amps in the distro block so the only one getting power was the tweeter amp and still had the whine.
   
  
• I swapped the tweeter amp out with an extra amp that I have and still had the whine.
   
  
• I took my small bookshelf home audio system and ran an extra rca from the hu to it, powered it up and I did not get the whine. which again, leads me to believe that the hu is not the culprit.
   
  
• I hooked a portable cd player to my tweeter amp and hooked up one of my bookshelf speakers to it and did not get the whine.
   
  
• I have tried the rca cable that was hooked up to my sub amp and the whine was still there.
   
  
• My rca's and speaker wires are ran on the opposite side of the power wires except for a 1 foot section where the power wire for the passenger seat gets close to them. Since I pulled the fuse to that power wire and still had noise that leads me to believe that the wire is not causing the problem.
  

The only thing I can come up with is that the resistance between the hu ground and the ground in the back is too high. Tomorrow I am planning on testing this with my multimeter.

I apologize as I am sure that this is pretty confusing to read but I wanted to give you a description of my problem as well as some steps that I have taken to troubleshoot it.

Can anyone help?

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[POLKAT 10+ year member]

bump

 

[2loud4u 10+ year member]

Try and ground the rca cables

It is a known problem with Pioneer.

 

[glennlewis 10+ year member]

You are close to answering your own problem...The only reason alternator whine occurs is that the ground potential between the head unit and the amp is too high..Ultimately all whine can be eliminated by decreasing the resistance between the two down to 0. I had a system once in my shop where we ran 10 10guage wires between the head unit and the amp ground to get all noise to go away...I know that seems extreme but it works.. Before you do that however you might want to try a torroid coil on the input power of the amp...

 

[Sleeklsc 5,000+ posts]

Try and ground the rca cablesIt is a known problem with Pioneer.

x2, had this problem with mine..

i just disconnected the rca harness from the back of unit with the car off and wraped some 16ga wire in and around all 3 outputs...wrap the wire around them while there still connected. leave enough of the wire so that you can connect it to the long bolt in the center of the back of the unit..( security bolt, use for a ground, has a nut) Not sure if the 880 has one but my 8600 did...

mine was fixed after i did that..i'm glad i read about that or i'd be going through the same crap as you..

 

[POLKAT 10+ year member]

problem has been fixed.

I finally got around to doing the big three. I checked the continuity of my rca's to the hu's chassis and it was .1 ohms so no problem there.

I made a pair of rca mute plugs and the noise persisted so I was 100% sure it was the amp. I figured maybe doing the big 3 helped level out the resistance between my components and I gave my spare amp another try.

The whine was completely gone. For whatever reason my Memphis PR70.2 does not play nice with my 880prs. //content.invisioncic.com/y282845/emoticons/blackeye.gif.66a1670f5aaf7f406e783a63e3387dc5.gif