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Question About Power Wire And Other Stuff

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=48850
Printed Date: May 29, 2024 at 12:51 AM


Topic: Question About Power Wire And Other Stuff

Posted By: rezzy 6th
Subject: Question About Power Wire And Other Stuff
Date Posted: January 29, 2005 at 12:17 AM

So I got my JBL GTO 1201.1 amp the other morning, for my pair of 12" CVRS, DVC, so I'll be wiring it down to a 4ohm load to get 787wrms to the subs. (Max are 800. so 787 is plenty for me for daily driving) The box is sealed, not ported, so I don't have to worry about the subsonic filter. So anyways I did some research and found I should use a 4awg power wire for that amp, but I noticed alot of people use 0awg wire. Should I go with a 0 instead of a 4 to get more power, or is that wire too much for that amp? Or what's the purpose of the 0awg wire? I don't know anything about wires so I hope this makes sense.

And can anyone point me to a place to order a good amp kit for this amp? Price isn't an issue if that matters.

Plus, what's a good speaker wire size for this?

And do you think I need to upgrade my battery and alternator for this amp? My battery and alternator are factory, and I have no problems now, I got neon under the car, neon in the car, plus adding that bigger amp to the picture, and hard to tell what I'll add next. Think adding that amp will hurt anything? If I need to upgrade, can someone point me to what certain battery and alternator I'll need? If you need to know anything about my car to tell me, let me know. I'm not familiar with this stuff.

Any advice will help. thanks!



Replies:

Posted By: dwarren
Date Posted: January 29, 2005 at 12:31 AM

a 4awg cable should be plenty, a larger cable will not give you more power only less resistance. As far as speaker cable size goes keep it short and the bigger the better, you can equate speaker and powe cable to a fire hose, the bigger the hose the more water flow, so go as big as possible but remeber to match your ground cable size to your power cable.

You will find out about the alt/amp upgrade soon enough, (the dimming lights syndrome) but an amp like that will probably do it. An alternator upgrade is the best idea overall, no caps, and wait on the battery. 



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Posted By: stevdart
Date Posted: January 29, 2005 at 12:25 PM

About wire sizes:  use the largest wire that your equipment and any future add-ons might require in the worst possible scenario....e.g. using the JBL at 2 ohms instead of at 4 ohms, etc.  To do that, add up the fuse values of all amps you are using and refer to Power and Ground Cable Specs to choose the appropriate gauge.  The chart lists amperes and the gauge wire needed for transfer of power without heating the wire.

You can use Ohm's Law to figure out what a value is when you know any two of the four values:  voltage, current, resistance, power.  To find out what amperage the speaker wire might need to carry, determine what the known factors are.  Power in watts is 787 and resistance according to your hookup is 4 ohms.

So for speaker wire, use  I = SQR( P/R ) and the chart above to determine gauge needed to transfer the current to the subs.  You'll see that the amperage comes out to be 14, which is in the range of 16 gauge wire.

You will be adding an additional draw on the car by adding the JBL.  You can find it's actual current draw by again using Ohm's Law.  You know the power to be 787 watts.  And you know the car's voltage to be about 14 volts.  Use I = P/E, and find an amp draw of about 56 when the audio is at full volume...

...then, you have to allow for peaks in the power (due to the music source) which will spike the current draw up into higher territory, possibly near 100 amps in brief spurts....

...which is enough additional current draw to possibly warrant an upgrade to the alternator and engine bay wiring.  It depends on what other equipment you have, how much room (capacity)  the current alternator has now, and how you use the electrical features in the car (like the rear window defrost, e.g.).






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