BillFitzmaurice.info

I actually poked a small hole in the grommet/nipple of one of the power runs going into the cabin from the engine bay. The wir loom is even inserted into the rubber. Then I did the best I could to tape that up with electrical tape. I got it a few times around on both sides of the wire so I think it's in place pretty well.

Oh, you're good to go then. Smart of you to use an existing grommet. Make sure the amp is well grounded. A short piece of wire, the same gauge as the +12v power wire, directly touching bare (unpainted) metal. If you have to rough up a small patch with a stiff wire brush or wire wheel, so be it.

Everything you ever wanted to know about 12 volt audio wiring can be found on this link. In car audio we use large gauge cable, not for the current flow, but to minimise the voltage loss over distance. Car amplifiers use unregulated power supplies which means power output is proportional to voltage in. With a 15 foot run, a 400 watt amplifier will lose about 22% of its rated power with 16 gauge cable and only about 4% with an 8 gauge cable. That's at full power, the difference is minimal at low power. That means not only do you lose amplifier power, but you also induce compression on the loud parts killing your sound quality.

A 50 amp fuse is safe to protect 8 gauge wire but don't go any higher. In my youth I had a 4 gauge unprotected cable running from the battery, under the carpet, to the trunk when it shorted out while driving. Having the cabin INSTANTLY fill with toxic, unable to see out the windshield smoke while driving down the street was an experience. I'm glad you took the time to fuse your lead.

Thanks for all the help. I put the wire loom around the power wire from where it leaves the side of the car and goes up along the seat and into the trunk. I also used the fabric mat to trace and cut some 1/2" Arauco Ply for a nice solid platform for everything. I'm still thinking about putting the RCA cables on the opposite side of the car, but I'll see if I notice any distortion. Well, now I have to start thinking about what I want to do for my next BFM project.