Car Stereos: 1994 Suburban Six Speaker Sound System Upgrades, speaker sound system, external amplifier

Question
Hi,

I have a 1994 Chevy Suburban that I plan to upgrade. Right now, it is configured with the factory "premium six speaker system." I'm planning on adding an Alpine iXa-W404 head unit and upgrading the speakers, but I'm confused on how to connect the six speakers to a head unit only rated for 4 speakers.

After some research, I found that Chevy installed a factory amp under the drivers seat to run the four rear speakers; does that mean I would need a new amp to handle the back 4 speakers running on the rear RCA's from the head unit?

I appreciate any assistance with this matter as I've never worked with car stereos before and have only a basic knowledge of car audio.

Thanks in advance.

Answer
Hi Terry,

You shouldn't have any problem making all six speakers work with your after-market head unit.  The fact that the Alpine deck only has four speaker outputs isn't really a problem, when you consider that the factory tuner pack only has four speaker outputs as well.  In the factory system, the external amplifier is used to drive the extra speakers, using the factory tuner's two rear speaker outputs as a source signal.  When you install the new head unit, it should work exactly the same way: the Alpine deck's speaker outputs will run directly to the factory amplifier, and it will continue to drive the rear speakers.

You'll just have to be sure that the factory amplifier is activated when you install the new head unit.  For this installation, you should be using a standard GM wire harness adapter (Metra 70-1858 or similar).  This adapter harness will be connected to the factory power and speaker plug, located at the factory tuner pack behind the ash tray.  In the adapter harness, you'll see a blue wire located next to the yellow and red power wires.  When you connect the adapter harness wires to the wires in the Alpine plug, be sure to connect the blue wire from the GM harness to the blue/white wire from the Alpine deck.  (Don't connect the Alpine deck's blue wire; you should be using only the blue/white from the Alpine).  This should activate the factory amplifier, and keep all your rear speakers working with the new head unit.

Hope this helps!

Brian