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Speaker wire length?


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8 replies to this topic

#1 of 9 AaronG

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Posted December 25 2001 - 01:07 AM

Hi guys,

I heard today that when you run the speaker wires they should all be the same length. So even though my front right is only 2 feet from the receiver the wire length should be the same as the wire going to my rears (about 18 feet). Is this true? Does the wire length make a difference?

Thanks,
Aaron

#2 of 9 Wayne A. Pflughaupt

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Posted December 25 2001 - 02:32 AM

Aaron,

Theoretically, they should be the same length, but not for the reason some say (i.e., the electrons will take longer getting to the speaker with the longer wire, thus causing delay). It’s more for the same reason that 12 ga. wire is better than 20 ga. wire: resistance. Naturally, the wire’s inherent resistance is relative to its length. Different lengths will not have the same resistance, and can make the speakers sound a little different.

How much so depends on the speakers and the wire lengths in question. For instance, I used to have a pair of 4-ohm speakers that had 2-ohm drivers. Needless to say, they were very “sensitive” (for lack of a better word) to added resistance from wire gauge and length. In another situation where I had with two subs, one needed only an 8-ft. speaker run, while the other needed about 35-ft. Because of the drastically different distances, I thought it would be best to keep both wire lengths the same.

Theories aside, Aaron, if you have 8-ohm speakers and are using heavy 12 ga. wire, you probably have nothing to worry about, especially considering the relatively short lengths in question. You will probably get more room-induced discrepancies between the two speakers (i.e., from one being closer to a boundary than the other, or something like that) than from differences in wire length.

Happy Holidays,
Wayne A. Pflughaupt
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#3 of 9 Derrick G

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Posted December 25 2001 - 05:13 PM

ArronG,

Wayne's right as usual.

When I used to work for a sound reinforcement company we did some experiments with this on a small system we had set up at an outdoor festival. The speakers were eight ohm cabinets connected with 12 gauge cables with 600 watts going to each cabinet. The wire was standard bulk 12 guage stranded cable costing about $.25 per foot. Definitely not what you would call high grade cable. Audiophiles would cringe in horror. Posted Image A 50 ft diffence in cable length would shift the stereo image about 3 or 4 ft. The short run was 50ft and the other 100ft. Keep in mind this was done by ear, so it's all subjective. Interestingly cutting back the long cable to 75 ft. moved the image back to just about dead center maybe at most a foot off. We were judging from about 30 ft from the speaker front plane.

As you can see the distances and cable lengths are far more than what you would see in a typical home theater. Using at least decent grade cable I don't think you will notice much difference. If calibrating with VE or AVIA you will adjust for the level differences anyway, but like Wayne I would try to keep the differences under 25 ft.


Derrick G

#4 of 9 Jim Mc

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Posted December 26 2001 - 06:48 AM

Well hello I have been out of the forum for quite some time.

I agree that the cable lengths should be similiar. But more as reflected in resistance than do to any phasing caused by time differences.

In general I would try to keep wire lengths and gauges to the fronts the same, and lengths and gauges to the rears the same. Most decent processors have delay time adjustments for center to sides offsets or rear vs front timing as these relate to physical seating distances and the speed of sound.

I believe the THX standard is roughly #14 under 50' and #12 over 50'.

That said electricity travels at between 60-80% the speed of light in wire. So the difference in time between the same signal hitting one speaker vs another 100' farther away is very very small. Electricity travels at about 1ft/ns thats (1 foot per .000000001 sec). So a 100' difference would account for a .0000001 time difference in arrival or a misphasing of .002 cycles at 20K hertz.

I am not saying that different lengths of wire do not make a difference. Just that the reasons are not the result strictly of the electrical conduction speed of electricity.

#5 of 9 George Martin

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Posted December 27 2001 - 01:40 AM

So if I have the wires for each pair the same lenth, and same guage I should be fine. But all the speaker wires dont have to equal the longest run?

Are you also saying that the longer runs should be of higher guage to compinsate for the impedance loss of the wire?

George

#6 of 9 Wayne A. Pflughaupt

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Posted December 27 2001 - 03:48 PM

George,

First, welcome to the Forum!

The answer to both questions is “Yes.” With the second question, though, a couple of “Depends:”

If the longer length is only a few feet, it wouldn’t matter. Generally, 14ga. is fine for runs up to about 50ft. – but using a larger gauge never hurts.

It wouldn’t hurt to “fudge” a little on the length/ga. standards for the rear speakers, since they aren’t as critical as the front three.

Happy Holidays,
Wayne A. Pflughaupt
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#7 of 9 Cees Alons

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Posted December 30 2001 - 07:14 AM

Most posters said it already: as long as the diameter is enough (I'd say 12 g or better), it doesn't matter that much.

In fact, I like to add one warning: having slightly different lengths is not as bad as having equal lengths and then having to roll up one of the wires. The coil you make that way may lead to audible differences in frequency colouring.

Cees

#8 of 9 Wayne A. Pflughaupt

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Posted December 30 2001 - 09:31 AM

Of course, you don’t have to coil the wire – you can bundle it. Not to make light of Cees’s recommendation, but coiled wire is reportedly more susceptible to pick up RF, if I recall, so that's definitely not the way to deal with excess wire.

It looks like I need to make an addendum to my earlier post on this thread. I spent the past couple of days installing a system in a teen club. The mains were bi-amped (i.e., true bi-amping with an electronic crossover, not what passes as bi-ampng in the hi-fi world). The amps were on one side of the stage, which necessitated speaker wire runs of different lengths. One run was 48ft, the other 32ft. (a 16ft. difference).

I expected a slight loss for the longer run (12ga. wire was used), but I was amazed to find, running the mids only with pink noise, a 3dB difference between the two speakers.

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Wayne A. Pflughaupt
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#9 of 9 Cees Alons

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Posted December 30 2001 - 01:51 PM

Quote:
Not to make light of Cees’s recommendation..

Wayne, I was trying to recommend against it!

Your remark about the bundle is correct, but I still wouldn't like it. In the past I did some "research" (meaning, I tried a lot different solutions Posted Image ) on the speaker wiring subject, and it made me to think even a bundle of wire on one side of a pair of channels is not very healthy - it's bound to make an audible difference between left and right.

Cees