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Amplifier Power Wire

Old 08-08-2002, 11:41 PM
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Question Amplifier Power Wire

Ok...I'm getting ready to rig the power wire for the new system and was needing some help. I am going to be running an MTX 6500D (225W/channel*[email protected])(am planning on bridging mono to 2 ohms) and a MTX 6304 (37.5/channel*[email protected]). I am planning on running 4 guage from the battery through a fuse (100Amp?) then to a 1 Farad Capacitor then to distribution blocks from the 4 guage down to 8 guage using 2 positive/2ground to each amp. Should I be worried about using the 2-8 guage or should I run a single 4 guage to each amp? Each amp has 3-25Amp fuses. Does that mean I need to run a 150Amp fuse at the battery? Let me know what you think!?
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Old 08-09-2002, 08:48 AM
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The two 8 gauge wires will be fine. try to keep the distribution block as close to your amps as possible. The shorter you run the 8 ga. wire the better. I think your fuse is fine, It should blow at the battery first (hopefully) and not at the amp which is scary, considering the amps are hundreds of dollars and the fuse is 2 dollars. The ground wires can just be run to the same mounting point, there is no need to run them through a seperate distribution box, unless it is for looks.
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Old 08-09-2002, 09:48 AM
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You are fine with what you are talking about. I am not sure about that amp however make sure it is ok to run it at 2ohms bridged mono. Lots of two channel amps are NOT 2 ohm stable when bridged mono.

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Old 08-09-2002, 11:36 AM
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Cool I agree with Audiofn...

...did I just say that?

A mono 2 ohm load is like a 1 ohm stereo load- you'll be able to cook burgers on those amps....

As for the wire, length matters. The longer the wire, the more resistance, and the more voltage drop. Resistance = heat. Heat and fiberglass do not get along well. How long are the wires?

You never want to have more than a .5 voltage drop across your wire.

For example, assuming 1,250 watts @ 65% efficiency (class a/b) and a wire run of 12ft, you will need one 4 gauge wire, as you will have a max draw of 139.4 amps.

The circuit breaker should be within the maximum of the amps draw, but less than what the cable can handle- that way there are no fires in case of a meltdown (cable short). The fuses in the amps protect the amps.

Here is a crude chart for cable size:
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Amplifier Power Wire-cablelength.gif  
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Old 08-09-2002, 03:40 PM
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I checked the "user manual" for the sub amp and it says that it is stable at a 2 ohm load and was actually tested at 2ohms. I'm not sure of the bridged mono but hopefully with ample power with the cap that the heat factor won't come into play. I'm breaking the 4ga down to a dist. block to 4-8ga outputs and will run 2-8ga. to each amp for both positive and negative. The 8ga. will be less than 2 feet I'm guessing. I don't have the boat back yet but when I have it, I am working with a limited amount of time. I should have it back on Saturday the 17th and it will be a bare hull inside so I have to install carpeting, install stereo, and the entire interior by Wednesday the 21 when we leave for the LOTO shootout. Talk about cutting it close! Thanks for the help.

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