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Discussion Starter · #1 ·
I am currently running an Alpine V12 (400-500W rms) with JL 12W7 subwoofer. I am using 8 gauge power wire with probably about 8ft from the battery to the amp. I don't know what the fuse amp is rated. I had been running it for about 2 weeks and it work great. This setup handle the JL 12W7 quite well.
I'm getting the JL HD750 next week which rated at 750W rms to replace my Alpine V12. My question is what is the drawback or consequences if I am still using the same 8 gauge power on this new amp?
Will it:
1. Damage the amp or subwoofer
2. Performance will not be at it potential
3. It should work fine

I really hate to change the wire to 4 gauge if it is unnecessary due to cost and labor.
 

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ABSOLUTELY upgrade. The 750's have a thirst for current. I've had some issues with some of the ones we've installed. Make sure you put a fuse near the amp as well as at the battery. ANd keep an eye on the power plug, they melt sometimes.

Jay
 

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Discussion Starter · #4 ·
Yeah, I do have a fuse between the battry and amp. I'm not sure what amp the fuse is rated at.
Melt? Now that is scary. Look like I better upgrade to 4 gauge power wire.
Thanks for the advice.

ABSOLUTELY upgrade. The 750's have a thirst for current. I've had some issues with some of the ones we've installed. Make sure you put a fuse near the amp as well as at the battery. ANd keep an eye on the power plug, they melt sometimes.

Jay
 

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actually, you really don't need to upgrade your power wire if that is the only amp you are running...at 8ft it will be fine.

go here WIRE and then about halfway down is a calculator you can use to find out it is enough.

Looks like 8 guage at 8 feet on a 75% efficient amp is good to 1000 watts
 

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actually, you really don't need to upgrade your power wire if that is the only amp you are running...at 8ft it will be fine.

go here WIRE and then about halfway down is a calculator you can use to find out it is enough.

Looks like 8 guage at 8 feet on a 75% efficient amp is good to 1000 watts
or that ^ :blush:
 

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From basic car audio and electronics>

.................................class AB....class D

8 awg.... 52 amps.... 430 watts.... 537 watts
 

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If he supercools the wire in it's entirety it should be fine , even as the voltage drops and the current flow increases , if it is just one wire he doesn't have to derate it and with liquid nitrogen surrounding the wire he can actually add a bit to the flow rating.

N.E.C. once you have read the various sections on the insulation type on your wire and the ambient temps recommeded are followed for ideal ratings you'll be fine when the amp is at 1/4 to 1/3 volume and the efficiency has dropped to 15% or 25% of its ideal number that is always quoted . . .

750 watts at 14.5 volts , etc..,
 

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Discussion Starter · #12 ·
Hmm...I am really thinking of trying with the 8 gauge first and see how it handle the JL HD750. I think it might handle fine, but the question is there any sound quality different when using 4 gauge vs 8 gauge?


actually, you really don't need to upgrade your power wire if that is the only amp you are running...at 8ft it will be fine.

go here WIRE and then about halfway down is a calculator you can use to find out it is enough.

Looks like 8 guage at 8 feet on a 75% efficient amp is good to 1000 watts
 

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Discussion Starter · #13 ·
Not a good idea for me since I have to drill another hole for the cable to pass throught.
On the concept of running 2 cables togehter to achieve better signal, does it work with speaker wire?
Currently, I am running 12 gauge speaker wire to the subwoofer. I think it is better if I run a 10 gauge to the subwoofer. Since I don't want to buy a 10 gague speaker wire and I have plenty of 14 gauge speaker wire, can I run 2 14gauge speaker wire to achieve the same level as a single 10gauge?

run another 8 guage...or 2 more.
 

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Don't forget that the fuse near the battery must not be higher than the power rating of the wire regardless of what the amp is fused at.
 

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Hmm...I am really thinking of trying with the 8 gauge first and see how it handle the JL HD750. I think it might handle fine, but the question is there any sound quality different when using 4 gauge vs 8 gauge?

Yeah I hope you wire doesn't melt then you have a nice little fire.
grab ahold of the wire check and see how hot it gets if it's warm to the touch you need much larger
 

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By all means. Definatley made a huge difference for me. I did 2 gauge for everything after I tried it on my amp's ground alone. I went the cheap route and went to advanced auto, if you ask for battery cable, they have it by the foot in the back. It's not pretty or anything but it's $1.88/ft. 1/4" techflex is a little tight but 3/8" probably fits perfectly over it.

 

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I have read somewhere a long time ago that a .5V drop across the power wire is considered acceptable and very safe. I tried to find it to post a link but i thought it come from that BCAE website. If this is correct which im sure someone shortly will confirm or deny, you could calculate the current it would take to drop .5v, and fuse the wire at that current. Standard copper wire has a R of .0006401/ft so at 10 ft you are allowed to draw 78 A to maintain a max of .5V drop. So if your car is runnig at 14V that is about 1092W that is save for that wire. Now account for the Eff % which is probably 60% ish so you an OPP of 655W. If you know better specs such as the actual Eff or exactly the R of your wire you can redue the math but the method will still hold true.
 

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Hello,
I'm new to this forum. Do you think there is anything wrong with using my RCA interconnects and 8 ga power wiring from an old install (12 years ago). What about the speakers, amplifiers, and cross overs.

JDS
 
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