Ok i have 2 amps that are going to be mounted in the boot of my 92 TR Magna.
I bourght 2x5m 2 gauge cable today just to see how it'd all work out. I found a few threads and even some pics on getting it all through the firewall so i should be right there but i'm wondering whether i need 2 gauge cable. Instead of running 4 chunky assed cables through the firewall (is it even possible?) i was thinking of just running the 2 gauge cable (2 cables, one for pos, one for neg) from the battery and through the firewall and then two sets of 4 gauge cable from there to the boot for the 2 amps. Would that work?
Amp 1: 4x100wrms (760wrms total)
Amp 2: 2x150wrms (500wrms total)

I noticed that theres no neg terminal on the amps, where does the neg power cable go?
I've read that the ground cable needs to be the same gauge as the pos power cable going in, if so, how the hell do i ground a massive thing like that? And would mounting the ground cable somewhere on the boot chasis work?

I'm not going to be much help, as I'm after simmilar info, but I do know that your earth should be short, thick and bolted to a bare-metal part of the body very securely for good sound.
Free :bump: cos I need to know this too :D

there should only be one cable running from your battery to the amp, you blow the amp if you put both to it...
only the red cable goes to the amp, (neg or pos i cant remember), you need to ground your amp, and as above, needs to be short, clean and bolted somewhere to the chasis for a good earth.

as for wiring, as thick a cable as you can get through the firewall, then split it with a distribution block in the boot to the 2 amps.
cheers

Ah ok, i see. I think it'd be better for me to just run both 2G cable from the battery to the boot. I've already bourght em and i'd rather not have them go to waste.

For your setup:

Run one 2guage cable from the +ve terminal of your battery to your boot. This is PLENTY.
Connect a 3way distribution block onto the end and then run a 4gauge cable to the +ve of each amp.
Run a 4guage cable from the -ve terminal of each amp to the chassis of the car (a big bolt of something already in your boot. Make sure you sand the paint away so that it makes a good connection. Keep this as short as possible.) You will need to buy a ring terminal for the cable. JB HIFI sells these and distro blocks pretty cheap.

Battery(+ve)
| (2 guage)
Boot (distroblock)
/ \ (4 guage)
AMP1(+ve) AMP2 (+ve)

Cheers
Pete

DONT run the 2nd 2gauge cable from the battery as your -ve to your amps! Its waaaay to long. This ground (-ve) connection on the amps needs to be as short as possible and the chassis of the car is a much better connector than the 2gauge cable.

Man i've got 10m of bloody 2G cable. Would i be able to jsut grab a distro block and split 1 2G cable into 2 2G cables for the amps? That means i could also use the -ve from the amps to the chasis 2G too. This would save be a fair whack of money since i've already bourght it all.

http://www.aussiemagna.com/forums/showpost.php?p=401782&postcount=9
posted in the other thread...

Dont run a second line for ground. The ground point should be straight to the chassis as close as possible to the amps. Beware of fuel tank.

Make sure you sand back the point well for a good connection.

Man i've got 10m of bloody 2G cable. Would i be able to jsut grab a distro block and split 1 2G cable into 2 2G cables for the amps? That means i could also use the -ve from the amps to the chasis 2G too. This would save be a fair whack of money since i've already bourght it all.

Yeah you could use 2guage all round as long as it fits in the connector on your amps... I think it will be a struggle but I you might do it. Would save you some money as well!

If it doesn't fit then i can just shave off some at the end.