J187

All though upgrading the ground strap from neg to chassis IS part of the "Big 3" I'm concerned by your post that you are considering just running a ground wire to the chassis without realizing that you are supposed to be changing the one that already exists, not just adding another. Also, unless its just something you want to do, you may want to verify that you have a ground problem w/ you vehicle before going to all that effort. YOu may not need the big 3 after all.

Ground all of your audio sources that are in the same audio loop to the same location. Other sources that have nothing to do w/ the loop can be grounded in isolation. An example of loop would be radio to amp. Ground the amps with the shortest possible wire OF THE SAME AWG AS YOUR POWER INPUT WIRE TO THAT AMP to the nearest, THICK metal structure. Use a gritty sand paper and sand the metal area if painted or treated with anything, and after connecting the ground wire, spray over it w/ an anti corrosive primer or paint. Using a smaller AWG wire for your interior mains is actually sound advice (sorry, pun intended). 12awg is right for the sub, but even 16 would be fine for your infinity speakers, 14 if you insist, but no bigger.

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