How to rewire common ground speakers?

[SwedishChef]

Hi guys, I have a 1987 Subaru XT with 4 speakers and I'm installing a new head unit and speakers. The stock speaker wiring uses 'common ground', and I've been advised to (somehow) un-do this by rewiring the speakers.

I'm not really planning to rewire the entire system and want to use as much of the stock harness as possible. This is not an audiophile-level build. What I don't understand is how I should rewire them. The stock harness (I have an adapter) only has a single ground each for Left and Right, but of course each of the 4 speakers has a ground connection, so I don't understand whether I need to 'split' the factory R-ground into 2 separate Front-Right and Rear-Right grounds, or from where, and same for the left channel.

Any help is greatly appreciated from you gurus! Thank you!

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[CSCStang]

You may not want to rewire, but it is what's needed.

 

[BoomTaco64]

you may not have to rewire as the speakers may have the wires already ran and the common ground part could be behind the radio.

 

[SwedishChef]

I just spoke with Crutchfield and he said that I can either:

1) run new ground wires from each speaker into the back of the new head unit, or

2) grab a 'floating ground adapter' which hooks up behind the head unit

He said the audio quality shouldn't be much different between the 2 options, but that I may lose my 'fade' control (which I don't mind).

Does this sound correct?

 

[CSCStang]

I just spoke with Crutchfield and he said that I can either:
1) run new ground wires from each speaker into the back of the new head unit, or

2) grab a 'floating ground adapter' which hooks up behind the head unit

He said the audio quality shouldn't be much different between the 2 options, but that I may lose my 'fade' control (which I don't mind).

Does this sound correct?

Option 2 would be easier. Not sure about that being the same quality though.

 

[SwedishChef]

Okay, I just rewired all the speakers. Not that bad at all actually, I'm glad I wan't afraid to tackle it. Then again, my car is easy to work on. Not sure it would have been as easy with my previous Audi ;-)

I'm still waiting on the head unit, new fascia trim and wiring harness to arrive. Look at this crazy factory 2-din space I have to work with. The entire thing is slanted.

 

[maylar 10+ year member]

The thing you have to understand is that the old systems used chassis ground as the negative side of the output. The minus lead of each speaker went to ground. The modern systems use 2 wires per speaker and neither of them are ground. So when your harness and new HU arrive make doubly sure that none of the speaker wires are ground, otherwise you'll cook the HU.

 

[SwedishChef]

The thing you have to understand is that the old systems used chassis ground as the negative side of the output. The minus lead of each speaker went to ground. The modern systems use 2 wires per speaker and neither of them are ground. So when your harness and new HU arrive make doubly sure that none of the speaker wires are ground, otherwise you'll cook the HU.

Thanks Dave, that's exactly the sort of speaking-to-a-second-grader instruction I needed! //content.invisioncic.com/y282845/emoticons/thumbsup.gif.3287b36ca96645a13a43aff531f37f02.gif

I've rewired the speakers with 14 gauge speaker insulated strand wire, each speaker has 2 wires, none go to ground (now). At the last moment I decided to get an amp for this setup, so I've routed all the speaker wires to the same spot under the passenger seat carpet, where the amp will go, and then of course the amp will be connected to the HU. I think I'm getting the hang of it now... a little.

One thing I could use some direction on is this: my new HU (Pioneer AppRadio SPH-DA110) has 2 pre-amp RCA outputs. My amp is a 4-channel amp, Polk D4000.4, and my 4 speakers are Polk DXi651. How should I connect the amp to the HU? Can I use the 2 HU RCA pre-amp outputs?

 

[CrossoverOre 10+ year member]

Some common ground systems only shared a neg output to the speakers and not actually connect to ground. With those all you had to do was run a new neg to one side of the car for front and rear and that was it instead of rewiring everything.

Use the rca outputs from the hu just make sure rear output is set to full range and not sub out.

 

[maylar 10+ year member]

Thanks Dave, that's exactly the sort of speaking-to-a-second-grader instruction I needed! //content.invisioncic.com/y282845/emoticons/thumbsup.gif.3287b36ca96645a13a43aff531f37f02.gif
I've rewired the speakers with 14 gauge speaker insulated strand wire, each speaker has 2 wires, none go to ground (now). At the last moment I decided to get an amp for this setup, so I've routed all the speaker wires to the same spot under the passenger seat carpet, where the amp will go, and then of course the amp will be connected to the HU. I think I'm getting the hang of it now... a little.

One thing I could use some direction on is this: my new HU (Pioneer AppRadio SPH-DA110) has 2 pre-amp RCA outputs. My amp is a 4-channel amp, Polk D4000.4, and my 4 speakers are Polk DXi651. How should I connect the amp to the HU? Can I use the 2 HU RCA pre-amp outputs?

The 2 preouts in the spec is misleading. It's actually 2 pairs - front and rear.