Source for cables, DIY style

[gdougherty]

A lot of confusion on speaker wire can be avoided with a ohm-meter and wire charts that list resistance vs length for various wire gauges.
As everything attached to the amps output terminals is part of the speaker circuit - the significance of the speaker line cannot be overlooked.
Any resistance in a circuit will cause a voltage drop and ultimately waste heat.
There is also the aspect of ampacity that get overlooked. When the impedance of a circuit is dropped, the current going through the circuit goes up.
The ampacity of 16 wire is 10a
Unfortunately some music stores have sold 50' runs 16 - 18 zip cord as PA
speaker leads.
When I had to install a 1 1/2hp 240v water pump 850' from my home,
I had to install very large triple #4 to avoid a large voltage drop.
125v goes in, a little over is available 121v at the pump end.

So armed with my multi-meter and knowledge of the resistance/ft of the cables, what should I be looking for?

[Bill Fitzmaurice]

Resistance 1%-5% of load will keep you out of trouble.

[Sydney]

With those tools and ohms law you can predict and verify through measurement your resistance and resulting voltage drop.
If you perform a continuity test on a wire length ( make a complete circuit of a 2 conductor run by shorting 1 end and measuring across the other with your multimeter set to low ohm range you will get the resistance of the run.
I think people forget sometimes that a 50 foot speaker line is 100 feet of conductor.
For the most part data on a wire chart is specific for solid conductor wire,
and that is not what is used for speaker wiring, but it is in general a good basis for comparison.
Flexible stranded may have less resistance if metals other than copper are in the strands, thats why measurement verifies.
There are other electrical aspects of wire that can get esoteric and probably not significant in a PA speaker circuit.
The way some types of speaker cable are run ( ie. haphazardly ) can have negative effect on the speaker circuit that gets overlooked as well.

[Dominik Gothe]

um i curently have a 25 foot cable, and it registers at 2.8 Ohm, one way what the hell?

btw: this was a very bad investment, as it turns out it is a 4 conductor wire, of which two conductors are wired to the banna plug, when you open it up, the cable looks pretty flymsy

is this possible?

if its true how is it effecting my sound?

thanks

[Bill Fitzmaurice]

um i curently have a 25 foot cable, and it registers at 2.8 Ohm, one way what the hell?
if its true how is it effecting my sound?

If true it's eating a third of your power.

[Dominik Gothe]

well, it may not be an efficent use of what i have right now but it'll have to get me through some gigs before I can afford good quality 10 or 12 awg wire

I want to get 10 awg, so that if I have to I can link several cables together.

thanks

[bgavin]

um i curently have a 25 foot cable, and it registers at 2.8 Ohm, one way what the hell?

You have a bad solder joint, corroded contact, or have not zero'ed your meter and leads.

I doubt that 24 gauge wire would show 2.8 ohms over 25 feet, let alone much larger stock.

[vlad335]

Speaking of DIY cable, would this be good to get?

http://www.cameltraders.com/search.php? ... =&keyword=

12/2 SJ speaker cable. I bought a bunch of Neutrik 4 pole ends from PE and want to make my own cables up. Don't for see a run longer that 40 feet.

[Dominik Gothe]

um i curently have a 25 foot cable, and it registers at 2.8 Ohm, one way what the hell?

You have a bad solder joint, corroded contact, or have not zero'ed your meter and leads.

I doubt that 24 gauge wire would show 2.8 ohms over 25 feet, let alone much larger stock.

your right it wasnt zeroed it actually is 2 Ohm, and i never said it was 24 awg

[gdougherty]

um i curently have a 25 foot cable, and it registers at 2.8 Ohm, one way what the hell?

You have a bad solder joint, corroded contact, or have not zero'ed your meter and leads.

I doubt that 24 gauge wire would show 2.8 ohms over 25 feet, let alone much larger stock.

your right it wasnt zeroed it actually is 2 Ohm, and i never said it was 24 awg

He didn't say yours was 24ga, just that not even 24ga would probably show such a high resistance over that distance.

[Dominik Gothe]

he is right then, it would have to be in the 30s, btw I took the cable out and measured it by itself, same result, ill try to get a second reading device

[Sydney]

vlad335 Re: 12/2 SJ speaker cable. I went to the manufacturer web site
http://www.colemancable.com/ and couldn't xref.
But it's probably equivalent to PE Carol SJ and if so the price is good.
( PE price on Carol is higher , and without the per foot option )

[Bill Fitzmaurice]

your right it wasnt zeroed it actually is 2 Ohm, and i never said it was 24 awg

If you're reading 2 ohms with 25 feet it's either 36 gauge or smaller or your meter is NFG.

[Dominik Gothe]

bill, I don't know if its my meter, but I would trust the cable to be that flimsy.

on another note, when shopping for cable I am looking for 12 awg 2C cable.

I assume that means that both of the conductors are 12 awg, is it possible that companies somehow calculated the gauge on the cable based on the sum of the two conductors?

thanks

[Sydney]

Maybe this will help:
http://www.epanorama.net/documents/wiri ... tance.html
Using this a base of ref:
a 50' run of 18 would be 1.3 ohms, .818 for 16, .516 for 14, .324 for #12
a 25' run would of course be 1/2 the above values
Result may vary with cable composition.
But you can see why 2.8 ohms is way above normal.