Summoning GlassWolf / Amp-Gauge question.

 

New member
Username: Osito852

Post Number: 3
Registered: Aug-05
Ok. (Sorry to make this long) I've gotten three different answers from four different people about what size gauge to power my system and need clarification. Right now I just bought an Alpine MRP-M350Mono subwoofer amp » » 350 watts RMS x 1 at 2 ohms (i'm gonna set it up for 2 ohms because it has a dual voice coil)
http://www.crutchfield.com/S-2tKbxYH83HQ/cgi-bin/ProdView.asp?I=500MRPM350

The site says it requires 8 gauge. One guy at the store said 8 guage rocksford fosgate wires would power up to 500 watts so I would be fine.

Two guys (1 online) and 1 guy at the (the same) store said that for my system in particular, I need a 4-gauge. And I quote from the online guy "...and MAKE SURE you have 4 ga power wire or bigger and a very good ground wire."

The unit came with 10 gauge!! (AUDIOPIPE PK-700 - 700 Watts Power Amp Kit )
http://www.mycarjams.com/car_audio/hazel/detail/APPK700
(it says 700 watts?? but it's 10 gauge...I'm guessing that max wattage)

Eventually I want to get a 4 ch amp that will be able to give 100 rms or so per channel for the inside 4 speakers. . .making my total RMS be 750.

This chart (http://www.electronixwarehouse.com/education/amplifiers/wiresize.htm)
says that for Total Power of RMS I should get a certain gauge wire. . .I see that for my small honda civic a 4 gauge would be enough (20 feet) for 750 watts.

What do I DO? Is the wiring it came with fine, eve n though it's 10 ga? Should I sell this wiring and buy 4 ga? Does the other amplifier I want to get have any bearing on the gauge size I should purchase? Thanks. . .
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 9268
Registered: Dec-03
well, here's where the confusion comes from.
Wire size depends on two factors. current draw, and length of the wire. Nobody has considered the length of the run.

From battery to d-block or amplifier is usually about 15 feet of wire, and that class D 350 watt amp will draw about 35A of current at peak.
at 15 feet you're right at the edge of the capacity of an 8AWG line, so if you go over 15ft, or you want to run a second amplifier at some point, just go ahead and use 4AWG wire from the start to be safe. If this is the only amplifier you ever plan to use, and you're under 15' in length of total wire, you're ok with 8AWG.
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