How to Gauge Speaker Wire

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Bubba had a bunch of email this week regarding our post on the Monster mistake of paying outrageous prices for designer cables.  The question that everyone wanted to know was what kind or size of speaker cable they needed to buy. Most cables/connectors used in used in hooking up your theater components comes in pre-fabbed, usually short lengths.

Speakers get put everywhere and often require no soldered ends or connections. They are run up in ceilings, under flooring, up in walls, and now with surround sound found in almost every system, all the way to the back of the room.   When the proper size (gauge) can be confirmed, simple lamp or “zip” wire can be acceptable.

Speaker Wire

Speaker wire is in fact, almost always simple, two conductor zip wire.  Again, built almost identically to the electric wire coming off of a table lamp. Gauge, as most of you know, is the diameter or thickness of the wire. Thicker wire is better, it carries more current with less loss. And just like your shotgun gauge, the numerical designation seems a little nonsensical at first, in that, the greater the number, the smaller the diameter. Your 10 gauge gun is tremendously wider in diameter than your 20 gauge snake gun. It will pass a lot more metal through it, just like the fatter, though smaller gauge wire specs.

Most speaker wire is copper, so all of you DIY electricians know that it can get pretty expensive. You are going to want the get the gauge you need. You will have to calculate the length of the cable run that you need to make, and know the rated impedance (expressed in ohms or Ω ) of your speakers. Most consumer systems have speakers that are 4 or 8 ohms, 4 being a higher resistance value.

Wire Gauge 4 Ω Speaker 8 Ω Speaker
20 10 foot max. length 20 foot max. length
18 15 foot max. length 30 foot max. length
16 25 foot max. length 50 foot max. length
14 40 foot max. length 80 foot max. length
10 100 foot max. length 200 foot max. length

 

Don’t just eyeball the cable spool or product package: DOUBLE CHECK for the actual wire gauge when you purchase. Some cable has extra thick jacketing to make it appear to be a higher grade. Note how some of the premium brands employ this trick.

Most home improvement stores carry speaker wire or lamp cord. Obviously the big box electronic retailers will have it. You should look for cable that has one conductor identifiable so that you can keep your polarity correct and maintain proper phase when you hook up your speakers to the terminals on the back of your receiver or home theater system. (positive to positive, negative to negative.) Usually, there is a stripe painted on one side of the PVC or Teflon jacket.

If you plan to run your wiring behind walls, and are doing a new build-out, (and not a retrofit), you might make sure that your cable is rated appropriately for any building or fire codes. Usually, a UL rating of CL-2 or CL-3 is fine. This rating will reflect how much heat it takes to burn that wire, and what kind of toxic fumes result. Keep in mind, a fire being spread behind your wall is never a good thing.  While most Bubba’s are not going to worry to much about a couple speaker wire runs, forensic insurance investigations might not smile upon bunches of flammable wire behind the sheetrock. Especially if you are putting this up in a friend’s house!

Make sure you get a solid contact with the wiring terminal in back of your receiver or amplifier. Don’t let those wire strands get so frayed or stripped out that a nice fat cable only has a couple hair width copper strands making contact!  Sometimes you’ll need to solder or attach standard or proprietary plugs to your cable. You might consider “tinning” the ends of your cables with a drop or two of solder to hold those loose strands together and make them stronger for spring clip attachment.

Keep your wiring lengths equal (or close to it) for matched speakers. Your front three speakers for surround sound should be about equal, and your rear two speakers should be equal.

Some receivers or home theater systems come with their own wiring. If it has proprietary, connectors or is specially designed for that system, that’s probably a good thing.  However, some manufacturers would like to appear generous by throwing in several feet of some cheap, thin, cable.  The type that has a few hair like strands of copper wrapped in a thin insulator.  By the time you try to strip it, there’s nothing left.  While this wire, (and other equivalent cheap, thin wire) will pass sound, it will probably be pretty tinny sounding at good volume… there’s just not enough copper to pass through the full frequency range at an appreciable power setting.

 

On the other hand, there’s no sense in buying a fiercely marketed, colorful cable in a cool package that nearly doubles the cost of your install.  There are many reputable acoustic experts that will debunk the myth of expensive cables sounding better.  Remember: the real science of psychoacoustics suggests that much of our hearing is subjective. So if I let you listen to two identical sounds and keep telling you that the second sound is better, you’re likely to start agreeing with me. This kind of sales “demonstration” is often used in so called “listening” tests comparing speaker wire.  (That, and just plain rigging the test with thin cables, thick jackets, etc.)

Remember, for cable manufacturers it doesn’t cost much more to wrap a thicker, colorful jacket around the same old boring copper wire and package it pretty. But package it right and make all kinds of claims about the audio magic that it makes happen – instant profit center.

If you have to buy the all new Godzilla Cable, or some other type of monster cable to impress your date…. Then go ahead. The salesman will love you.

 

 

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