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have i been told wrong? - amp wiring 

 

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 Post subject: have i been told wrong? - amp wiring
Posted: Sat Jul 28, 2007 6:06 pm 
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g'day all...i went and bought 2 amps the other day and wiring kits and everything from jb. monoblock 800wrms and 600wrms 4 channel audiobahns....and i bough a $200 stinger wiring kit as the dude did me a great price. now only thing is i asked if the kit was enough for the two amps and he said yea its fine......so what he told me to do is run the 4 gauge from the battery into the 150amp fuse, then run it to the back seat where the amps are mounted and use a splitter box and then run 2 seperate 4 gauge wires to each amp....ive done this but soo far only had time to do the monoblock and it sounds great but im not sure if this will supply enough power for the speaker amp aswell?? or will it?

 

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Posted: Sat Jul 28, 2007 7:15 pm 
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Check this site out mate... Will help you: http://www.bcae1.com/wire.htm 4G wire will carry roughly 130amps so it should be fine for your two amps.

However, 2G direct from the battery to a distribution block then 4G to each amp would be ideal.
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Posted: Sat Jul 28, 2007 7:17 pm 
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yeah shouldnt have a problem with that size cable... im just running 8 gauge to a 520 wrms amp and it seems fine...

 

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Posted: Sat Jul 28, 2007 9:24 pm 
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agreed with the 2 above me...should work fine. Though as mongoose said, 2Gauge wiring from the engine to the boot would be better, though not really necessary. Make sure you have another fuse in the engine bay...don't want you to burn the interior if there was ever to be a short.

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Posted: Sat Jul 28, 2007 10:23 pm 
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yeah you'll have no dramas.

Unlike this bloke that came into work today - he's just bought a Powersomething 5000W 2 channel amp (yes 5000W!!!), and he's worried about weather the big thich a** cable will be enough to power it. The thing probably has as much power as the amp in my CD player...
In the end I told him to try Arora (our local power supplier - like the mob that supply power to your house/business and own the power lines in the street) and they should be able to hook him up (I was being a smart a**) - he didn't relise and said ah yeah that'd be a good idea...

 

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Posted: Sat Jul 28, 2007 11:05 pm 
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haha classic mate....gotta love those customers that think there on a good thing but really got no idea and act like they do haha....cheers fellas

 

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Posted: Sun Jul 29, 2007 12:18 pm 
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Running 8gauge into the positive terminal from the distribution block should be enough, something you may not know is that you should run a BIGGER NEGATIVE lead, as the power comes from the negative terminal :)
I run 4gauge into the boot, fuse under the bonnet to the distributor, 8gauge to the amps and 4gauge negatives.

One amp has the negative wire wrapped around the big screw holding the gas tank down, then it duck taped up :)
Matt

 

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Posted: Sun Jul 29, 2007 12:27 pm 
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So can you explain to me why the negative sould be bigger than the positive?
This has me a little confused...

 

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Posted: Sun Jul 29, 2007 5:16 pm 
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because electrons acturley flow from the negative terminal to the positve, caled electron flow , but in actural fact the cable should be the same size because electrons have to flow through both cables an will be limited to the smaller wires capacity, not a issue for a car audio setup tho lol..

conventional current flow is wot people use to beleive how electricty flows. doesn't really matter once again tho lol..

 

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Posted: Sun Jul 29, 2007 5:18 pm 
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^ Spot on buddy.

 

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Posted: Sun Jul 29, 2007 5:21 pm 
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the negative is the return path or ground of the vehicle. While i personally think its s**t to have a bigger earth, it should be same size as positive, it wouldnt hurt. make sure you sand the paint back where ever you decide to put the earth.

Oh, and to be really techo, if your going to run big earth for your audio, you should also upgrade the earth from your engine block to battery, and even run more earths from the chassis and body. Only the real hardcore dudes bother

 

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Posted: Fri Oct 12, 2007 9:36 pm 
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-GAS-MAN- wrote:
Running 8gauge into the positive terminal from the distribution block should be enough, something you may not know is that you should run a BIGGER NEGATIVE lead, as the power comes from the negative terminal :)
I run 4gauge into the boot, fuse under the bonnet to the distributor, 8gauge to the amps and 4gauge negatives.

One amp has the negative wire wrapped around the big screw holding the gas tank down, then it duck taped up :)
Matt


Erm.......rubbish!

The formula for power is P=IV, or P=I^2R. The higher the resistance of the cable, the less current it is able to carry without behaving like a fuse. As the current flowing through both the cables is the same (electrons don't get lost, or consumed.....), you want the longer cable to be heavier gauge than the shorter. It makes sense to just spec big-a*** cable for both.

You are quite correct about the direction of electron flow though (Neg to pos). Any electronics/electrical engineer (Myself included) will tell you that "holes" flow positive to negative
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Posted: Sat Oct 13, 2007 8:23 pm 
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fcollingwood wrote:
-GAS-MAN- wrote:
Running 8gauge into the positive terminal from the distribution block should be enough, something you may not know is that you should run a BIGGER NEGATIVE lead, as the power comes from the negative terminal :)
I run 4gauge into the boot, fuse under the bonnet to the distributor, 8gauge to the amps and 4gauge negatives.

One amp has the negative wire wrapped around the big screw holding the gas tank down, then it duck taped up :)
Matt


Erm.......rubbish!

The formula for power is P=IV, or P=I^2R. The higher the resistance of the cable, the less current it is able to carry without behaving like a fuse. As the current flowing through both the cables is the same (electrons don't get lost, or consumed.....), you want the longer cable to be heavier gauge than the shorter. It makes sense to just spec big-a*** cable for both.

You are quite correct about the direction of electron flow though (Neg to pos). Any electronics/electrical engineer (Myself included) will tell you that "holes" flow positive to negative



Exactly, it is a phallicy that the cables need to be the same size as it is dependent on the current and the cable length, it is a cosmetically good thing to do but it has no basis in ohms law that the super short ground cable has to be the same size as the much longer positive cable let alone needing a larger ground cable which is total crap......
It is amazing some of the garbage that gets sprouted about car audio....

 

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Posted: Mon Oct 15, 2007 11:42 pm 
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Really its not going to be an issue what cable you use. I used 8g cable (yes, only about 5mm in diameter) to my 2 channel 500w amp for the sub. Then i went to add the 1000W 4 channel for the speaks and got all worried but then soon realised that is wasnt an issue anyway.

So i have a 8g cable running to a distro block with 2 x 8g cables coming from that for the amps.

As for the earths, i had proper connectors on the bastards and sanded to bare metal on the chassis where the rear seats bolt in. I had both my amps mounted on the back seat.

 

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Posted: Tue Oct 16, 2007 4:48 pm 
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outlawxr6 wrote:
fcollingwood wrote:
-GAS-MAN- wrote:
Running 8gauge into the positive terminal from the distribution block should be enough, something you may not know is that you should run a BIGGER NEGATIVE lead, as the power comes from the negative terminal :)
I run 4gauge into the boot, fuse under the bonnet to the distributor, 8gauge to the amps and 4gauge negatives.

One amp has the negative wire wrapped around the big screw holding the gas tank down, then it duck taped up :)
Matt


Erm.......rubbish!

The formula for power is P=IV, or P=I^2R. The higher the resistance of the cable, the less current it is able to carry without behaving like a fuse. As the current flowing through both the cables is the same (electrons don't get lost, or consumed.....), you want the longer cable to be heavier gauge than the shorter. It makes sense to just spec big-a*** cable for both.

You are quite correct about the direction of electron flow though (Neg to pos). Any electronics/electrical engineer (Myself included) will tell you that "holes" flow positive to negative



Exactly, it is a phallicy that the cables need to be the same size as it is dependent on the current and the cable length, it is a cosmetically good thing to do but it has no basis in ohms law that the super short ground cable has to be the same size as the much longer positive cable let alone needing a larger ground cable which is total crap......


Yup - I forgot to mention the fact that the longer cable would have a higher resistance, therefore should possibly be the heavier gauge, if there is going to be a heavier gauge in the set up.

outlawxr6 wrote:
It is amazing some of the garbage that gets sprouted about car audio....


Yup too, I see the same in home theatre, and in IT, but I have noticed the cowboys in the industry slowly disappear.
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