Wire Length really that much difference? (1 Viewer)

[Anthony Lengyel]

Ok I was told by my home theater dealer that you should make the wires to the fronts and center all the same length. He contiunued to explain about something of the human ears can detect upto 15ms delay or something..

Now I guess my question is this true? Before I wired up my speakers long enough to reach them..

i.e. Front right 6 feet
Frnt Left 10 feet
Center 3 feet

So what he is saying that I should wire all 3 up with 10 feet lenghts. Is this true?

 

[Patrick Sun]

Maybe if the differences were in terms of hundreds of feet, it might make a sonic difference.

But for your own personal peace of mind, perhaps using the same lengths would do you good.

 

[RayJK]

186,280*5280=983558400fps therefore 1ft takes 0.0000000010167164 seconds, 7 ft difference would be 0.0000000071170151 seconds. I doubt you can hear this.

 

[Edward J M]

In a typical HT set-up, the length of decent grade 14 gauge or 12 gauge speaker wire will have absolutely no sonic impact with respect to time delay or resistance.

If you have VERY long runs, definitely use 12 gauge to minimize resistance build-up. Other than that, don't worry about different length runs causing time delays - that's simply ridiculous and patently untrue.

The time delays you can program into your digital processor for speaker distance to the listener are several orders of magnitude higher than any time delay caused by one speaker run being a few feet longer than the other. Good grief - find another dealer - who knows what else he has been telling you! :b

Regards,

Ed

 

[Doug BW]

Sound moves through the air about a million times slower than an electrical signal moves through a wire.

So if the wire to your left speaker is a foot shorter than the wire to your right speaker, merely move your head one millionth of a foot to the right to compensate.

 

[Anthony Lengyel]

"So if the wire to your left speaker is a foot shorter than the wire to your right speaker, merely move your head one millionth of a foot to the right to compensate.
"

Hahaha I like that.

 

[TimTurtino]

2 things--

Speed of signal in a wire isn't speed of light. Not that it's that much slower, but just saying...

I _believe_ that the reasons people give for having wires that are the same length (and rears wires that are multiples of the lengths of the fronts) has more to do with resonances than speed of signal through the wire. While I still personally think this is bunk (my rears are 43' and 57' respectively ), it's at least a little more believable bunk.

Me

 

[John Royster]

It has nothing to do with speed/delay and everything to do with the effect the wire has when joining speaker and amplifier. The wire can indeed change frequency response depending on length, amplifier, speaker, wire.

Ideally keep the front three channels the same length to balance any changes the wire may induce. If less than ideal is OK, then use any lenght necessary.

 

[Scott Falkler]

First,make sure your wires are the same length.
Next,make sure you turn off the heater/AC and any fans that may make noise.
Also make sure it isn't windy or raining outside as you may hear it and it will detract from your experience as well.
Sit directly in the middle and DO NOT turn your head as the sound will degrade many orders of magnitude. Bass will sound bloated and heady, the midrange will be stoked and defunct, and the high frequecies will be party cloudy with a chance of precipitation.
Don't forget to make those speaker wires the same length!!!

 

[Mat_M]

If making your speaker wires the same length makes you feel warm and cozy inside that's fine. But here's a link that will tell you the straight up truth about speaker cabling:
http://home.earthlink.net/~rogerr7/wire.htm

I work in an engineering lab and can tell you that a speaker wire can be viewed as a simple transmission line model. Since we are dealing with frequencies between 20Hz and 20kHz (very low), parasitic capacitance and inductance play a SUPER minor role in terms of signal loss. As long as you have a nice 14 or 12 gauge wire, the difference between speaker wire length can be huge. The misconception people mix up is the fact that actual electrons move along a wire at a VERY low speed (http://www.amasci.com/miscon/speed.html). However, view electrical current as a hose with water -already- in it: When you turn on the water at one end, it's pretty much instantaneous that water comes out the other end. The speed of electricity is VERY close to the speed of light in a vacuum (1/3*c).

Now assuming what your sales rep said is true (15ms time delay)...This would require a difference of 4,917,855 feet of wire between the two speakers. So from a technical viewpoint, you'd be perfectly fine with different wiring lengths.

 

[John Royster]

parasitic capacitance and inductance play a SUPER minor role in terms of signal loss

I wouldn't call 1-2 db of attentuation a super minor role.

 

[Mat_M]

1-2 dB in how much difference of lengths? 3000 feet??? If you're loosing 1-2 dB in a length running from your receiver to your speaker, get yourself some new speaker wire.

Here's something to put into perspective: On the very last slide of this presentation (http://www.ul.ie/~rinne/ee6471/ee6471%20wk9.pdf) is an example of an electrical pulse sent through 24AWG wire for a distance of 1km. The loss here is about 1-2 dB, but we are talking about 24AWG wire, which is TINY compared to 14 or 12 gauge wire; and on top of that, the length is 1000 meters. A square pulse like this, when changed through a Fourier transform, yields a sum of frequencies far higher than 20kHz.

So please explain to us how you will loose 1-2 dB in 14 or 12 gauge wire running from your receiver to your speaker.

 

[TimTurtino]

The speed of electricity is VERY close to the speed of light in a vacuum (1/3*c).

*grin*

Yeah-- 2/3 of the speed of light is basically negligible.

Me

P.S. -- Mat_M -- I do understand that, for these purposes, it is-- heck, even if electricity traveled at 1% of the speed of light, it would be more than fast enough to make a few feet a moot point. I just thought it was funny to think of 200,000 meters/sec as being a small thing...

 

[John Royster]

Mat,

The problem with that presentation is there wasn't a speaker attached to it.

I'll let the other EEs explain what happens at 20Khz on a speaker that presents a less than 1 ohm load. I graduated way too long ago to remeber EE201. All digital for me now.

 

[Steve Zimmerman]

John, OK I have a Master's Degree in EE and I'll chime in to say that what you're describing is inaudible.

--Steve

 

[John Royster]

So a few db of attenuation is inaudible? It always has been for me.

Another member BruceK was kind enough to enlighten me as to how cable lengths can affect high frequencies by looking at the whole system instead of just a wire. Oh well, its not worth arguing over. To each his own I guess.

 

[Bob McElfresh]

(So why isnt this thread in "tweeks and connections"?)

Ok I was told by my home theater dealer ..

So here is a guy trying to sell you something? He doesnt perchance sell wire BY THE FOOT? This should make you somewhat suspicious.


We did the math on another fourm and found that to get a 1% phase shift, one speaker wire would have to be 80 feet longer than the other.

Having several feet of wire coiled up behind your speakers to make the lengths the same is really, really bad.

Cut your speaker wires to length + 1-2 feet for "play" and so you can trim off an inch or two every 2 years. (The exposed copper will oxidize and the periodic cut/strip/re-connect is considered normal maintance.)

A word on wire thickness:

Several speaker sites (not wire sites) recommend the following gauge based on wire-length:

1-10 ft: 16 ga
11-20 ft: 14 ga
20+ ft: 12 ga

So you do need THICKER wire for the long runs.

Most of us buy a spool of 12 ga and use it everywhere. Check out the "Sound King" brand from www.partsexpress.com.

Even if you believe that exotic copper will make a dramatic difference in sound (it does have some, but only a slight bit), start with the good-quality Sound King wire and use it for several months. Then go to your dealer and ask to "audition" some of his more expensive wire. Decide for yourself if the change in sound is worth the $$$.

Hope this helps.

 

[Julio Ortiz]

.

 

[Steve Zimmerman]

John, I'm saying I don't believe a 20ft length of normal 12 guage wire attenuates the audible range of frequencies by even 0.05 dB.

That's my opinion--for now, but I'll measure it just for fun.

--Steve

 

[Mat_M]

Maybe there's been a misunderstanding here: 1-2dB of attenuation means loosing between 21% and 37% of your power. I am positive that this will not happen in 14 or 12 gauge speaker wire between the frequency range 20Hz to 20kHz, running from your power source to your speaker. Can you imagine how hot the wire would get if you lost that much power in it?

John, now if what you're referring to is the actual wire+speaker combo impedance curve, then we're talking about something entirely different.