18 Guage wire killing my sound?

[n2audio 5,000+ posts]

18 is definitely small for 500w, but assuming 2 ohms and 3 feet...

Switching from 18 ga to 12 ga will net you .12db. That's nowhere near audibility.

You're trying to move around 15A at full power. 18 is only intended for about half that.

 

[Turbo Travis 10+ year member]

It's not a matter of an audible difference, it's a matter of doing the job correctly or half assed. Switch the wire out for something larger. Being that the run is so short (and assuming you can get the wire by the foot), I'd probably just use 12 gauge and be done with it. It'll be there if you ever upgrade to a larger amp, etc.

 

[brynm 10+ year member]

18guage wire has current capacity of 18amps, so YES if your amperage is higher than this out of the amp, you could be severly limiting the amount of power going to your subs. Change it out with 12guage, either way, it wont hurt, might help, and is not exspensive.

ORLY, Did you know that you could put a huge amount of current down an 18AWG wire? The current carrying capacity is a limit for safety purposes. A wire will not magically say "oh look, there is 30A going through me and I'm only rated for 10A, I better stop that." A larger wire has less resistance so it can carry more current without heating up.

The difference in resistance between a 3' run of 8awg and 18AWG is negligable. It basically boils down to what the OP wants to do. 500 watts at 2 ohms is only about 15.5A

18 is definitely small for 500w, but assuming 2 ohms and 3 feet...Switching from 18 ga to 12 ga will net you .12db. That's nowhere near audibility.

You're trying to move around 15A at full power. 18 is only intended for about half that.

Back that up with some math please.

 

[brynm 10+ year member]

A chart I found,

Wire Gauge Resistance per foot

4 .000292

6 .000465

8 .000739

10 .00118

12 .00187

14 .00297

16 .00473

18 .00751

20 .0119

22 .0190

24 .0302

26 .0480

28 .0764

so let's say you have 3 feet of wire between the terminal and your sub, a round trip is 6' ( 3' to the sub and 3' back).

For 8AWG 6 x .000739 = 0.004434 ohms

For 18AWG 6 x .00751 = 0.04506 ohms

.04506-.0004434=0.040626 ohms

your losing about 10W due to the resistance of the wire.

 

[n2audio 5,000+ posts]

18 is definitely small for 500w, but assuming 2 ohms and 3 feet...Switching from 18 ga to 12 ga will net you .12db. That's nowhere near audibility.

You're trying to move around 15A at full power. 18 is intended for less than half that.

Back that up with some math please.

Figure it out for yourself.

I wouldn't have posted it if it wasn't factual.

There are some very handy calculators at bcae1.com/wire.htm

by hand I got .09, depending on what values are used for wire resistance.

ORLY, Did you know that you could put a huge amount of current down an 18AWG wire?

Huge amounts? The recommended fuse size for 18ga is 5A. I don't know at what point it would start to heat up but at 15A I bet it's happening.

The difference in resistance between a 3' run of 8awg and 18AWG is negligable. It basically boils down to what the OP wants to do. 500 watts at 2 ohms is only about 15.5A

.019 ohms for 18

.0018 for 8

It's a factor of 10.

That's all beside the point. The issue is current, and 15A is way too much for 18 ga.

 

[brynm 10+ year member]

Huge amounts? The recommended fuse size for 18ga is 5A. I don't know at what point it would start to heat up but at 15A I bet it's happening.

I don't doubt that it is, how much I'm not sure but if it hasn't caused a problem in the four years he had the sub I doubt it will now. It's a gain of maybe 1/10 of a dB, it's not as he was wondering "killing his sound", and that is if it is 18AWG wire. The difference between 18AWG and 16AWG wire is very small about 1/100th of an inch in diameter.

As long as the wire doesn't show any sign of a problem (melting insulation) I wouldn't worry about it, but as I said it's up to the OP to do what he wants.

 

[Louisiana_CRX 5,000+ posts]

think of wire size as a funnel .....what happens to water? the same thing happens to current....

 

[Thedeadly1 10+ year member]

i run all my highs/mids on 12 gauge and 10 gauge on my subs per post

 

[Lakota 5,000+ posts]

.1 dB isn't much. The least amount of sound pressure difference that I've been able to accurately identify is .3 dB. People may say I'm bullshitting, but it's true.

 

[NightDrifter05 10+ year member]

Just change it out and get it over with. It's not like it is going to cost a arm and a leg and take all day to do it. It may or may not make a huge difference but if you ever plan to run more power you will already have it done.

 

[grassroots 10+ year member]

A wire will not magically say "oh look, there is 30A going through me and I'm only rated for 10A, I better stop that." A larger wire has less resistance so it can carry more current without heating up.

EXACTLY...

that's why i believe the whole "big 3" is a load of shit (better not say that too loud, fan boys will attack) ... if a wire is receiving too much amperage, it will not limit the amount, rather it will just heat up and melt...

SO... if your wiring isn't melting, it's doing just fine...

 

[brynm 10+ year member]

EXACTLY...
that's why i believe the whole "big 3" is a load of shit (better not say that too loud, fan boys will attack) ... if a wire is receiving too much amperage, it will not limit the amount, rather it will just heat up and melt...

SO... if your wiring isn't melting, it's doing just fine...

That's not true though. The Big three is a good idea, especially if you are drawing a lot of current. You are having a voltage drop across that wire from the resistance of the wire, that's why it heats up.

He is having voltage drop too, it's just no enough to make an audible difference.

 

[grassroots 10+ year member]

That's not true though. The Big three is a good idea, especially if you are drawing a lot of current. You are having a voltage drop across that wire from the resistance of the wire, that's why it heats up.
He is having voltage drop too, it's just no enough to make an audible difference.

unless you install a high output alternator, there is no reason whatsoever to increase the wire size to your battery...

and the largest variable in voltage drop is the length of wire. and four feet of wire (max) is not going to drop any significant voltage... regardless of its circular mil area...