Equal length speaker wire? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 18 Old 07-23-2019, 04:41 AM - Thread Starter
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Equal length speaker wire?

I am about to open up my sheetrock and replace the tiny gauge speaker wire that our builder had installed, and have a question regarding cable length.

I realize that most receivers and pre-amps room correct, but with that software fix removed from the equation does speaker wire length need to be equal between a pair of speakers? As an example, my a/v gear is on the left side of my room. As such, I can go from the amp to the left mid-field surround with a 6’ run. But its mirror image speaker in the right side of the room would need 40’ or so. Would having two different length runs effect anything that could be heard by the ear only? Or do the electrons move so fast I’d need miles of cable before introducing issues (other than extra resistance 😉 )?

Thanks
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post #2 of 18 Old 07-23-2019, 04:51 AM
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It should not make a discernible difference to your ears or your electronics. Just make sure you are using speaker wire rated for in-wall use. It usually has a protective jacket around the wire to help prevent fire hazards.
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post #3 of 18 Old 07-23-2019, 05:09 AM - Thread Starter
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Yup, it is cl-2 rated.

Thanks!
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post #4 of 18 Old 07-23-2019, 09:55 AM
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Quote:
Originally Posted by TexmasterPEB View Post
Would having two different length runs effect anything that could be heard by the ear only? Or do the electrons move so fast I’d need miles of cable before introducing issues (other than extra resistance 😉 )?

Thanks
The speed of electrons through wire is, at it's slowest around 7/10ths the speed of light. The speed of light is around 186,000 miles per second or 300,000 kilometers per hour so at worst, the electricity will move at around 125,000 miles per second through wires. . IF you could hear the delay of 0.1 mS or 1/10,000ths of a second... that would mean you should keep the length difference less than 12.5 miles. Generally speaking, humans don't have a problem with 1mS delays so you can stretch that to 125 miles if you like.

It would be hard to do a listening test though--the speed of sound is 690 miles per hour so a fraction of an inch difference between your speakers and ear drums would require a highly sophisticated measuring system and putting your head in a vice.

Back to reality, no--it won't make a difference as far as electron delay goes. What would make more of a difference is the voltage drop across 40 feet of wire VS the shorter cable. Use the proper wire guage to eliminate that problem and you'll be fine.

Good question though, I've seen people have 25 feet of speaker cable wrapped in a coil to make the cables "even". Tightly wrapping speaker wire in a coil creates additional issues that would impact the sound than the speed of electrons but I can't blame people to try. For the record, generally it is not a good idea to go past 50 or 60 feet with speaker cable so no worries about different lengths. Generally speaking, shorter is better be it speaker cables, power cords or interconnects--no need to keep them all the same length.
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post #5 of 18 Old 07-23-2019, 10:20 AM - Thread Starter
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Quote:
Originally Posted by 18Hurts View Post
Quote:
Originally Posted by TexmasterPEB View Post
Would having two different length runs effect anything that could be heard by the ear only? Or do the electrons move so fast I’️d need miles of cable before introducing issues (other than extra resistance 😉 )?

Thanks
The speed of electrons through wire is, at it's slowest around 7/10ths the speed of light. The speed of light is around 186,000 miles per second or 300,000 kilometers per hour so at worst, the electricity will move at around 125,000 miles per second through wires. . IF you could hear the delay of 0.1 mS or 1/10,000ths of a second... that would mean you should keep the length difference less than 12.5 miles. Generally speaking, humans don't have a problem with 1mS delays so you can stretch that to 125 miles if you like.

It would be hard to do a listening test though--the speed of sound is 690 miles per hour so a fraction of an inch difference between your speakers and ear drums would require a highly sophisticated measuring system and putting your head in a vice.

Back to reality, no--it won't make a difference as far as electron delay goes. What would make more of a difference is the voltage drop across 40 feet of wire VS the shorter cable. Use the proper wire guage to eliminate that problem and you'll be fine.

Good question though, I've seen people have 25 feet of speaker cable wrapped in a coil to make the cables "even". Tightly wrapping speaker wire in a coil creates additional issues that would impact the sound than the speed of electrons but I can't blame people to try. For the record, generally it is not a good idea to go past 50 or 60 feet with speaker cable so no worries about different lengths. Generally speaking, shorter is better be it speaker cables, power cords or interconnects--no need to keep them all the same length. [IMG class=inlineimg]/forum/images/smilies/smile.gif[/IMG]
Best. Reply. Ever. Thanks for the info and the laugh!

Also, 186,000miles/sec is not equal to 300,00km/hr. Slacker! 😉
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post #6 of 18 Old 07-23-2019, 11:52 AM
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Quote:
Originally Posted by TexmasterPEB View Post
Also, 186,000miles/sec is not equal to 300,00km/hr. Slacker! 😉
Guilty!

It is something like 299,000 miles and change. However, you noticed I said "around 186,000 miles or 300,000 KM" That legally makes my statement vague
and covers the slight variances in rough math equations. I then made a rough guessimate of the speed of light VS the speed of electrons through copper
wire which further added poop to the punch bowl.

Even with the slop in my math, you are golden so enjoy your build.
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post #7 of 18 Old 07-23-2019, 12:36 PM - Thread Starter
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Quote:
Originally Posted by 18Hurts View Post
Quote:
Originally Posted by TexmasterPEB View Post
Also, 186,000miles/sec is not equal to 300,00km/hr. Slacker! 😉
Guilty!

It is something like 299,000 miles and change. However, you noticed I said "around 186,000 miles or 300,000 KM" That legally makes my statement vague
and covers the slight variances in rough math equations. [IMG class=inlineimg]/forum/images/smilies/biggrin.gif[/IMG] I then made a rough guessimate of the speed of light VS the speed of electrons through copper
wire which further added poop to the punch bowl.

Even with the slop in my math, you are golden so enjoy your build. [IMG class=inlineimg]/forum/images/smilies/smile.gif[/IMG]
186,000 miles/sec = 1,077,614,062 km/hr. Your time unit changed between US and metric. That’s all I was sayin! 😉

Build will begin soon. Thanks!
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post #8 of 18 Old 07-23-2019, 12:47 PM
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all this science....if I have my speakers 1/10 of an inch off measured by laser, I can hear the difference. easiest way to hear is by imaging location of instruments/voice. is it still accurate...sure I guess, but its easy to hear when speakers arent setup correctly. now with speaker cable length, I use same length as thats what was sold to me as a pair for L/R....but my center and surrounds all have different lengths/custom. what sucks is if you move and those custom lengths dont work in new place.

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post #9 of 18 Old 07-23-2019, 12:56 PM
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Is it possible he said all that with a straight face?

Michael
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Did you really need to quote that entire post in your reply?
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post #10 of 18 Old 07-23-2019, 02:04 PM
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post #11 of 18 Old 07-24-2019, 08:23 PM
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Quote:
Originally Posted by 18Hurts View Post
The speed of electrons through wire is, at it's slowest around 7/10ths the speed of light. The speed of light is around 186,000 miles per second or 300,000 kilometers per hour so at worst, the electricity will move at around 125,000 miles per second through wires. . IF you could hear the delay of 0.1 mS or 1/10,000ths of a second... that would mean you should keep the length difference less than 12.5 miles. Generally speaking, humans don't have a problem with 1mS delays so you can stretch that to 125 miles if you like.

It would be hard to do a listening test though--the speed of sound is 690 miles per hour so a fraction of an inch difference between your speakers and ear drums would require a highly sophisticated measuring system and putting your head in a vice.

Back to reality, no--it won't make a difference as far as electron delay goes. What would make more of a difference is the voltage drop across 40 feet of wire VS the shorter cable. Use the proper wire guage to eliminate that problem and you'll be fine.

Good question though, I've seen people have 25 feet of speaker cable wrapped in a coil to make the cables "even". Tightly wrapping speaker wire in a coil creates additional issues that would impact the sound than the speed of electrons but I can't blame people to try. For the record, generally it is not a good idea to go past 50 or 60 feet with speaker cable so no worries about different lengths. Generally speaking, shorter is better be it speaker cables, power cords or interconnects--no need to keep them all the same length.
Quote:
Originally Posted by TexmasterPEB View Post
Best. Reply. Ever. Thanks for the info and the laugh!

Also, 186,000miles/sec is not equal to 300,00km/hr. Slacker! 😉

The net speed of electrons n a wire for an AC signal is zero. For DC the speed very low. See Electric drift the Wikipedia article below or do your own search on the subject:

https://en.wikipedia.org/wiki/Speed_of_electricity

The speed of sound is about 767 miles per hour. See the Wikipedia article below or do your own search:

https://en.wikipedia.org/wiki/Speed_of_sound

The additional issues are caused by the inductance of the wire, which is greatly increased in a coil of wire.
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post #12 of 18 Old 07-25-2019, 06:29 AM
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Quote:
Originally Posted by bigguyca View Post
h
The speed of sound is about 767 miles per hour. See the Wikipedia article below or do your own search:

https://en.wikipedia.org/wiki/Speed_of_sound

The additional issues are caused by the inductance of the wire, which is greatly increased in a coil of wire.
Thanks for the clarification,

I pondered where the 690 MPH number came from, read the information and now I remember. I took a course in aviation and the 690 MPH number came from calculating the mach speed of jets as sound slows down at high altitude and very cold temps. That makes sense, I don't think people will be listening to their systems at 40,000 feet up in brutally cold temps. 767 MPH at 59F at sea level, good to know...thanks!

I'm sure Nordost and Audioquest is pondering producing "altitude adjusted cables" the "LA" version for low alttitude and the "Denver" version for higher altitude cables. For an extra charge (of course) they can custom build them to match your altitude. Coming soon!
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post #13 of 18 Old 07-25-2019, 10:46 AM
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Originally Posted by 18Hurts View Post
The speed of electrons through wire is, at it's slowest around 7/10ths the speed of light. The speed of light is around 186,000 miles per second or 300,000 kilometers per hour so at worst, the electricity will move at around 125,000 miles per second through wires. . IF you could hear the delay of 0.1 mS or 1/10,000ths of a second... that would mean you should keep the length difference less than 12.5 miles. Generally speaking, humans don't have a problem with 1mS delays so you can stretch that to 125 miles if you like.

It would be hard to do a listening test though--the speed of sound is 690 miles per hour so a fraction of an inch difference between your speakers and ear drums would require a highly sophisticated measuring system and putting your head in a vice.

Back to reality, no--it won't make a difference as far as electron delay goes. What would make more of a difference is the voltage drop across 40 feet of wire VS the shorter cable. Use the proper wire guage to eliminate that problem and you'll be fine.

Good question though, I've seen people have 25 feet of speaker cable wrapped in a coil to make the cables "even". Tightly wrapping speaker wire in a coil creates additional issues that would impact the sound than the speed of electrons but I can't blame people to try. For the record, generally it is not a good idea to go past 50 or 60 feet with speaker cable so no worries about different lengths. Generally speaking, shorter is better be it speaker cables, power cords or interconnects--no need to keep them all the same length.
Yep - way back in 2007 while I was a newbie, and "trusted" those with x,xxx's posts, someone named "IrritateGuy" and "COF" or similar grumpy name on the Sound and Vision HT forum advised me speaker wire for long runs needed to be within 10% so the resistance/impedance was close enough for the amp to see similar load...
https://web.archive.org/web/20080208...rd?board.id=57

I bought that hook/line/and sinker!

My7.1 layout back in 2007


the AV closet is front RH side, so the left side and left rear surrounds were much longer runs than their right counterparts ...
Hence I did this ...
Now, I made the loops random to mitigate EMC reception as much as possible


In then end ... I wasted $$'s ... live and learned ....
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post #14 of 18 Old 07-25-2019, 04:22 PM
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Thanks for the clarification,

...
But, you are correct about the Velocity of propagation.
https://www.scte.org/TechnicalColumn...ropagation.pdf
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post #15 of 18 Old 07-25-2019, 08:24 PM
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But, you are correct about the Velocity of propagation.

https://www.scte.org/TechnicalColumn...ropagation.pdf

The link you have posted describes velocity of propagation. The original post described the velocity of electrons, which is a very different quantity.
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post #16 of 18 Old 07-26-2019, 05:42 AM
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I've seen the velocity of my propagation decrease dramatically over the years. I wonder if electrons experience the same phenomenon.
Maybe I need shorter wires. Size DOES matter.
Michael

Did you really need to quote that entire post in your reply?
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post #17 of 18 Old 07-26-2019, 07:06 AM
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post #18 of 18 Old 07-27-2019, 05:54 PM
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The link you have posted describes velocity of propagation. The original post described the velocity of electrons, which is a very different quantity.
Yes, I know, thanks. Added info, that the propagation velocity is near light speed. I'd consider 0.7 near enough.
Now he knows both.

Last edited by CharlesJ; 07-27-2019 at 11:00 PM.
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