Subwoofer Cable

[Jack N]

I’m in the process of building a home theater and I’m to the point where I need to run sub cables. I’ve noticed that there’s a rather wide range of wire gauges available so how do you know what size to get?

 

[tyhjaarpa]

How long run do you need for your sub cable?

 

[Jack N]

There will be multiple cables run all with different lengths. The shortest one will be roughly 20 feet and the longest one will be about 60 feet.

 

[tcarcio]

I have 2 of these available if you are interested. $40 each shipped in the lower US. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&uact=8&ved=0CDUQFjAH&url=http://www.amazon.com/AudioQuest-class-subwoofer-cable-Discontinued/dp/B000F1Z8GA&ei=Eq-_VL6rF8SOyAS1toGwDQ&usg=AFQjCNGWbRepEmm1nKUqNSSf3pq4KLTMBQ&sig2=iealiV4NP0OWqNdYoc1ElQ

 

[Speedskater]

Are the subs - Active? with built-in amplifiers.
Or passive? with the amplifiers at one location and the subs at another.

If the subs are active, is the cable an:
RCA connector unbalanced interconnect?
or a XLR connector balanced interconnect?

 

[Hookedonc4]

We use Monoprice.

They have different lengths.

For passive we use number 12 from Monoprice.

Not sure why I can't add attachment.

 

[Jack N]

All of the subs are active and use the unbalanced RCA connectors.

 

[BoredSysAdmin]

Sub cable should be shielded/coax . For 50ft runs or so , use RG/59 gauge, for 100ft or more definitely stick to better RG/6

 

[Jack N]

Thanks (sincerely) but that really doesn’t help. Everybody and their brother seems to making RG6 and I’ve seen the AWG size go from 18 all the way down to 27. Is there a mathematical formula, guideline, table, or anything that clarifies what gauge wire should be used to carry an LFE signal over X amount of distance?

 

[BoredSysAdmin]

Don't buy cables from my brother (i don't have one) but if it's from reputable company (monoprice sorta counts)
here's the proper chart:
http://www.w4rp.com/ref/coax.html
and here is calculator:
http://www.arrg.us/pages/Loss-Calc.htm

 

[Jack N]

So it looks like an LFE signal would lose next to nothing in a properly sized cable, which is great. The question I still have is - What’s the proper size for X amount of distance? IE: Will the 27AWG version work well for my 60 foot runs, or is it only good for a couple of feet?

 

[BoredSysAdmin]

So it looks like an LFE signal would lose next to nothing in a properly sized cable, which is great. The question I still have is - What’s the proper size for X amount of distance? IE: Will the 27AWG version work well for my 60 foot runs, or is it only good for a couple of feet?

From Wikipedia :
the term RG-6 is generally used to refer to coaxial cables with an 18 AWG center conductor and 75 ohm characteristic impedance.
http://en.m.wikipedia.org/wiki/RG-6

 

[Sheep]

Also, make sure you have CL-2 rated cables if they are going in wall!

SheepStar

 

[Speedskater]

For long RCA interconnect runs, what matters most is low end-to-end resistance of the shield. The next consideration is reasonably low total capacitance. The size of the center conductor doesn't matter at all, neither does the Radio Frequency Characteristic Impedance.
The Blue Jeans Cable sub-woofer pages explain it rather well and their LC-1 cable is an excellent choice.
http://www.bluejeanscable.com/store/subwoofer/index.htm
http://www.bluejeanscable.com/store/subwoofer/LC1-design-notes.htm

 

[notbraveheart]

Thanks! I'll give it a try.

 

[highfigh]

I’m in the process of building a home theater and I’m to the point where I need to run sub cables. I’ve noticed that there’s a rather wide range of wire gauges available so how do you know what size to get?

Line level, use Rg6- it's easier to find than RG59. As a better hedge against noise, use RG6 quad shield.

 

[TLS Guy]

So it looks like an LFE signal would lose next to nothing in a properly sized cable, which is great. The question I still have is - What’s the proper size for X amount of distance? IE: Will the 27AWG version work well for my 60 foot runs, or is it only good for a couple of feet?

The conductor resistance will not be significant as LFE unbalanced is a high impedance input. For a sub capacitance is not an issue

What you need to worry about is the shield for a 60 ft run. You need the heaviest shield possible.

You could have problems with 60 ft. This is what balanced runs are for.

Make sure you put the cables in conduit. If you have trouble you can convert to balanced at the receiver and unbalance it at the sub. If you don't use conduit and have a problem you will be screwed.