#6763 - 12/11/08 01:36 AM
Difference in L & R Speaker Wire Length
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Gunslinger
Registered: 04/21/06
Posts: 96
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I'm wireing my new basement for home theater and I run the speaker wire in the walls. After I was done I realized the left speaker wire is about 4 feet shorter then the right. I haven't put up drywall yet. Should I get some more wire and re-run the left to be the same length as the right? Could I splice in a 4 foot piece or would a splice cause problems?
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#6765 - 12/11/08 02:57 AM
Re: Difference in L & R Speaker Wire Length
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Desperado
Registered: 01/06/08
Posts: 334
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Originally posted by E'pin Sen Ob:
If you do notice a delay in the speaker you may need to use your receiver/processors channel delay to balance it out. Most receivers incorporate this option and all processors have it these days. At close to the speed of light for the electrons in question, I think even Superman on steriods would not be able to detect a delay of several feet of cable. :rolleyes:
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#6767 - 12/11/08 05:38 PM
Re: Difference in L & R Speaker Wire Length
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Desperado
Registered: 09/10/05
Posts: 443
Loc: Santa Barbara, CA
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If the human hearing apparatus could be influenced by a phase difference of, let's say, 10 degrees at 20 KHz (which I don't think any adult raised in an industrial environment can detect at a useful level anyway), how big a difference in interconnect or speaker wire length would be required to cause that difference? Nice little calculation problem. My guess is it would be a mile or so. If that's true, a difference of a few feet, or even a hundred yards or so, between one side and the other is really negligible. But the effects on signal level and/or frequency response might be significant. I'll bet Altec could tell us.
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#6768 - 12/11/08 06:46 PM
Re: Difference in L & R Speaker Wire Length
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Desperado
Registered: 01/06/08
Posts: 334
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Originally posted by psyprof1: If the human hearing apparatus could be influenced by a phase difference of, let's say, 10 degrees at 20 KHz (which I don't think any adult raised in an industrial environment can detect at a useful level anyway), how big a difference in interconnect or speaker wire length would be required to cause that difference? Nice little calculation problem. My guess is it would be a mile or so. If that's true, a difference of a few feet, or even a hundred yards or so, between one side and the other is really negligible. But the effects on signal level and/or frequency response might be significant. I'll bet Altec could tell us. The way cables behave is a complex matrix of the influences of inductance, capacitance, resistance, frequency and impedance presented to the line. Suffice to say that the extremely low output impedance of all modern solid state amplifiers lowers any significant influences from reactance, either capacitive or inductive. What remains is resistance. This would influence the damping factor if the additional length of the one cable was significant enough to contribute enough resistance to lower the effective damping factor below around 20 on the speaker with the longer wire. However, with any reasonably sized speaker cable, the difference in length would have to be on the order of 100 or more feet to make any measurable difference, let alone any audible difference. The difference in propagation delay between two cables of anything short of many, many miles is going to be so short as to be only detectable in the laboratory.
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#6769 - 12/11/08 08:52 PM
Re: Difference in L & R Speaker Wire Length
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Gunslinger
Registered: 04/21/06
Posts: 96
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So a few feet won't make any difference at all and I can put drywall up without worrying about the speaker wire imbedded in the wall. Thanks for the info everyone.
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#6770 - 12/11/08 09:14 PM
Re: Difference in L & R Speaker Wire Length
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Desperado
Registered: 01/06/08
Posts: 334
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Originally posted by Daryl: So a few feet won't make any difference at all and I can put drywall up without worrying about the speaker wire imbedded in the wall. Thanks for the info everyone. Yeah. Just don't coil the excess as this will create an inductor, which, though unlikely to cause any audible or measurable difference, is best avoided. Simply let the excess fall randomly into the empty space.
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#6771 - 12/11/08 09:49 PM
Re: Difference in L & R Speaker Wire Length
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Gunslinger
Registered: 06/01/07
Posts: 91
Loc: Panama City, Florida
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A couple things. First, since it's presumably something like zipcord, the two conductors run in parallel and are closely spaced. Because of this the speaker current will tend to cancel and the coupling between adjacent runs of wire will be minimal. Coiling the excess will have no marked effect.
Second, the delay introduced by an additional 4 feet of wire will be about the same as moving the speaker back by 0.000,001 inches. Light travels about 11.8 inches per nanosecond; the velocity in cable is about 1/3 that, so we have about 12 nanoseconds delay. With sound at 1 foot per millisecond we have about 12/1,000,000ths of a foot or about 1 one-millionth of an inch. 20 kHz is about a half inch wavelength; the delay is negligible unless you've positioned your speakers with this accuracy. :-)
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#6772 - 12/11/08 11:40 PM
Re: Difference in L & R Speaker Wire Length
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Gunslinger
Registered: 11/13/08
Posts: 161
Loc: United States
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This has topic has provided useful information to me. I've always read that I should keep my speaker wire lengths relatively similar. When I re-wired my system and relocated my components, I tried to keep my speaker wire lengths somewhat uniform. Basically, this turns out to have been a frivolous effort, especially since my rear left speaker is located in the opposite corner of the room from my components and it is a fairly large room. I believe I may have enough extra speaker wire to bi-amp my front L/R speakers with this new knowledge!
Thanks for the information everyone!
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