So there will be 2ea 8ohm burial subs hooked up to the Crown Cdi1000. I did some rough measurements and its about 160-170' from rack to a junction box/point where it then branches off to the two subs. The run then to each sub is about another 60' each. What wire gauge would be needed?

You should AT LEAST use a 70 volt amp and a transformer at each subwoofer.

When you consider that a 120V electrical circuit of that length must be at least 12 gauge, and perhaps larger, it's unreasonable to think that the speaker wire could possibly be any thinner.

Resistance losses are related to the square of the current. An amp that draws* 200 watts at 120v would draw a current of 1 2/3 amperes. An amp outputting 200 watts into 8 ohms would output a current of 5 amperes. Power losses at the 8 ohm level would be about 9 times the losses at 120 volts.

You can mitigate this somewhat by using a 70 volt amp and a local transformer. (This is what we do with concealed subwoofers at Nobu Malibu, even though the wiring distance is only about 60 feet.)

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*obviously the amp draws more than that since it's not 100% efficient at turning electrical power into audio output, but making this approximation gets us into a ballpark close enough to think about the effects.

8

I use two pair 14g and have run a couple hundred feet. No problem. Thats PER sub. We run that no matter how far though ( as in less distance as well).

Hmmm. What about doubling up 12/2? I think though that is 9.

When doubling up, do you still put the colors together from each pair (i.e red/red & white /white) or is each wire run a channel (red/white) + (red/white)?

[Link: belden.com]

Caution regarding using a transformer on a low frequency driver; since transformers tend to behave differently across the musical spectrum, choosing the correct one would be important.

And then they also have this:

[Link: belden.com]

Its doesnt hurt having thicker gauge wire, aside from cost. The advantage of having higher gauge wire now is later if they want to add another sub, on same channel, your could be good to go.

Double up red and white for positive, green/black for negative. PER sub.

What if I have and would be pulling 12/2 and then doubling up?

For DB, I currently have 16/2, 14/2 and 12/2.

So where confusion sets in is Snap's own quick start guide for the Cdi. It shows for 8ohm 12ga that you can go up to 291' at an 11% power loss. Then for 70v, they show a blanket 2783' for 16ga wire.

The 70v distance goes against Gidden's chart, unless you are looking at hooking up maybe 1 sat speaker at those numbers. This is then what made me question the wire gauge needed for the burial sub. This is the furthest distance I have had to run thus far for subs and sat's.

Since this is only powering a sub and not a full range speaker does that have an impact or extend the typical max distance?

Going back, if I did double up 12/2ga, does it need to be for the full distance to each speaker? Or from the junction point where it then branches to the subs on opposite corners of the pool area, can the wire be stepped down? Think that is only when it comes to 70v but just verifying.

I really dont understand your question. What if you double up 12/2? Fine. Double it up. one pair positive. one pair negative. you can daisy chain on a second sub. run both pair to the subs. dont have one pair to one and one to another. Use both pair, daisy to each other.

you said "Going back, if I did double up 12/2ga, does it need to be for the full distance to each speaker?" when you say speaker, i assume you mean SUB. No need to do more than 16 on any 70v speakers. You would use 12/4 to first sub, then you COULD do 12/2 last sub I guess, but i dont and wouldnt. There just is not enough cost difference. Just use 12/4 all the way.

Look, your basic answer is that you want to use the heaviest gauge wire that you can to get the best fidelity. And if you use 70 volt and have to get a transformer, it MUST be able to handle the power that's going through it. This is not cheap.


It should be confusing even before this! They don't give any information as to how an 11% or other particular loss affects the sound. They imply that maybe 11% is okay. Use the largest wire you can use.


No, quite the opposite. Loss is related to the square of the current, as I said. And the most power sent through the wire is in the bass, so bass is where you'll have the most losses.

This is a surprise idea to me: I learned a rule of thumb, which is that the power level of normal audio decreases by 3 dB per octave. It's just how it is: it takes more power to reproduce bass at level X than treble at level X. This should mean that bass signals will be attenuated more along long wires than highs! But I've never heard that mentioned at all.


No, not for theoretical reasons. It needs to be as thick as possible for as large a percentage of the run as possible. In other words, use the biggest wire you can.

A practical reason not to mix wire gauges is that if you mix wire gauges you will have splices and splices are imperfect points of connection. It's better to have one long unspliced piece of wire than a piece of wire with a splice in it. This "better" may only be theoretical if you make good splices; or if the splices are in any way exposed to the weather, they may be worse connections in a year or so.

Focus here: and all of this may be inaudible.


Use the thickest wire you can in as many places as you can.


As for which colors go where when you double up the wire, there is no electronic reason to select any one color over another. Just stick with the convention* we normally use: red and whites are hots while green and black are grounds.



*A "convention" is just the way we have chosen to do things every time, always the same, so that when we look at connections someone else made, we won't have to figure out which colors are hot and which are ground. "Convention" has no basis in electrical facts.

Ever run across speaker wiring done by an electrician? To them, the convention is that black is hot and white is neutral (kinda groundish). Red is hot and green is ground. See how that would be confusing to us but electrically just fine?

What I was referring to was if I am doubling 12/2 at the sub would one 12/2 be a positive and the other a negative or would you still tie red's together for positive and whites for negative? If it was a 12/4 then a no brainer in my mind based on normal convention.

As far as the run, if subs were daisy chained, the run would be even longer. The shortest run from the house would be to a junction box on the SW side of pool. From there a wire run to the NW side as well as the SE side is about the same distance. Thus, branching off at the SW point would give me the overall shortest distances in overall wire length for the 2 subs. Does that make sense?

The fact that we didn't understand your exact issue hints that it seems obvious: stick with convention. Red is plus and white is.... wait a minute! Where did you get 12-2 with red and white wires? Red and white are both plus in four-wire cables. I've only seen red and black, though European cables use different colors. I'm not aware of red and white, but obviously it could happen.

Other than that, I'd stick as close to convention as possible. If you were to wire it up as two separate wires, where one is a red and white pair and is the hot, and the other is a red and white and is the ground, how do you instantly identify them? Put a tape note on them, that can be damaged? Use a marker that might fade or spread over time? No. Stick with convention.

If you really have a red and a white as a pair in a jacket, I'd put notes at each end of the runs, and in any paperwork given to the client, call that out. Even better would be to use cable with a black wire and a red wire.


Without an actual illustration, I'll just take your word for it. Use the least amount of wire and the thickest wire you can use.

Ernie,

Ugh. I keep tripping on my own words. Have red & white on the brain thinking 12/4.

12/2 = Red & Black. My initial instinct standard wiring (red+red and then black+black) but was confirming the standard isn't something different when running x/2 and doubling up.