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Do speaker cables for L & R channels have to be the same length?

Do left and right channel speaker cables have to be the same length?


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mr.k

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You guys sometimes confuse me. You're spending aeons examining the smallest bump in FR chart, but on the other hand - "different length of cables? sure, it's ok!!" :)

Once I cabled my room, and because of the room configuration one of the speaker cables was 4 times longer...left speaker 8 meters, right 2 meters.
Left speaker was obviously quieter, therefore music was completely "off centre". Initially, I thought something went wrong with the speaker, but when I exchanged speakers, the other one became quieter. Then I realized different cables lengths = different resistance.

Of course, you can balance with balance knob, if you have one :) I couldn't live without balance control, and how absence of balance knob became normal is beyond me.

Anyway, since that day, I always use cables of the same length.

IMO, most differences that "true" audiophiles hear when switching cables is because resistance/impedance of different cables is different.
 

Doodski

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IMO, most differences that "true" audiophiles hear when switching cables is because resistance/impedance of different cables is different.
The resistance versus the attenuation from it (good copper) is so slight over a 12 gauge cable that it is near zero. Like 1.588 mili Ohm per foot. Most if not all people's multimeters cannot even measure this and a very sensitive dual input Ohm meter is req'd that costs thousands for one.
 

CoolHandDuke

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For oxygen free copper speaker wire, you'd need massive length differences to cause an issue. Better to have different lengths than a bunch of extra cable that you need to handle which can indeed cause issues.
 

mr.k

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I was using no name speaker wire, so probably it wasn't best copper in the world. On the other hand, cables shouldn't matter, most of us will agree.

If so, where the difference in volume came from in my case ?



The resistance versus the attenuation from it (good copper) is so slight over a 12 gauge cable that it is near zero. Like 1.588 mili Ohm per foot. Most if not all people's multimeters cannot even measure this and a very sensitive dual input Ohm meter is req'd that costs thousands for one.
 

Doodski

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I was using no name speaker wire, so probably it wasn't best copper in the world. On the other hand, cables shouldn't matter, most of us will agree.

If so, where the difference in volume came from in my case ?
It's possible you had CCA (copper clad aluminum wire) or worse. CCA has about ~30% more resistance give or take. But even then the length was not that long and still should not have that much attenuation to cause a obvious volume difference. I never buy inexpensive budget speaker wire. We had some issues at the retail level selling 18 gauge that had the insulation/dielectric that would be thicker and thinner between the 2 conductors and we had some customers with shorted wire. Not good to be selling such stupidity. So we tossed those rolls in the garbage and stopped selling it. It was quality 16G & 12G after that.
 

ebslo

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Let's just math it out, I'll make up a hypothetical situation:
12 guage wire, left leg is 4', right leg is 12' because it has to go over
something. Speakers are Revel F208 with min low frequency impedance of 3.4 ohms,
and about 3.6 Ohms at 20kHz. Most speakers have higher impedance at high frequency,
but not these. Amp has low-frequency output impedance of 0.023 Ohms for nominal
"damping factor" of 347, rising to 0.26 Ohms at 20kHz (just because that's what my
amp's spec says).

Low frequency analysis at 90Hz (min load impedance)
----------------------------------------------------

Left:
Rwire = 0.00159 Ohms/ft * 4 ft * 2 = 0.0127 Ohms
Damping factor = 3.4 / (0.023 + 0.0127) = 95
For 1 V source, I = 1 / (3.4 + 0.023 + 0.0127) = 0.2911 A
Vload = 0.2911 A * 3.4 Ohms = 0.9896 V

Right: (same equations as above)
Rwire = 0.0382 Ohms
Damping factor = 56
I = 0.2889 A
Vload = 0.9823 V

So Right is -0.064dB down from left.

High frequency analysis at 20kHz
--------------------------------

Inductance = 0.3 uH / ft
Due to skin effect, resistance is increased by about 1/0.75 for 12 AWG wire at 20kHz,
so wire resistance is 0.00159 / 0.75 = 0.00212 Ohms/ft

Wire impedance = |(0.00212 + j(2 * pi * 20e3Hz * 0.3e-6H))| = 0.004325 Ohms/ft

Using same equations as above with all impedances for 20kHz:

Left:
Rwire = 0.0346 Ohms
Damping factor = 12.2
Vload = 0.9244 V

Right:
Rwire = 0.1038 Ohms
Damping factor = 9.9
Vload = 0.9082 V

So Right is -0.15dB down from left.

Conclusion
----------

I'm not hearing that, not even close, not even if I could hear above 14kHz.
 

sergeauckland

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I can relate a story from my days when I had my ill-fated foray into being a hifi dealer.

At that time, there had been some stuff in the magazines about the importance of equal length cables, so as was my wont, we wanted to test this. We had 100m rolls of bulk cable, so I put a 2m length on one 'speaker and the full 100m of 79 strand cable on the other. Then we listened, and compared with 2m on each 'speaker. None of us in the shop could hear any difference, whether to image position or anything else. None at all.

If 100m to 2m wasn't audible, then any likely difference in lengths domestically would be well down into nothingness.

I can understand people who buy silly-priced cables wanting equal lengths as they're easier to sell on when they 'upgrade' their cables for even sillier prices. I can also understand buying longer equal cables to allow 'speaker arrangements in a room to change, I've done that myself as my listening room has moved a few times over the years, but as far as audible changes go, none.

S
 

Kal Rubinson

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Once I cabled my room, and because of the room configuration one of the speaker cables was 4 times longer...left speaker 8 meters, right 2 meters.
Left speaker was obviously quieter, therefore music was completely "off centre". Initially, I thought something went wrong with the speaker, but when I exchanged speakers, the other one became quieter. Then I realized different cables lengths = different resistance.
Hmmm.
My CT system (5.1) has 12ga. speaker cables and they were custom-cut and terminated by the manufacturer. Because the electronics are in one corner of the room, the lengths vary from 2M (Left Front) to 12M (Right Surround). However, there are no acoustical level differences (audible or measurable) among the identical speakers (LF, C, RF or LS, RS). Front vs. rear are different speakers so there are real differences there.

I have no doubt that there are real and predictable resistance differences correlated with length.
 

mr.k

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If it wasn't because of wires, then only remaining cause could be temporary glitch in left/right balance in the receiver.
Now I'm completely confused and intrigued...I will definitely check it again.


Hmmm.
My CT system (5.1) has 12ga. speaker cables and they were custom-cut and terminated by the manufacturer. Because the electronics are in one corner of the room, the lengths vary from 2M (Left Front) to 12M (Right Surround). However, there are no differences (audible or measurable) in level among the identical speakers (LF, C, RF or LS, RS). Front vs. rear are different speakers so there are real differences there.
 

ex audiophile

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If it wasn't because of wires, then only remaining cause could be temporary glitch in left/right balance in the receiver.
Now I'm completely confused and intrigued...I will definitely check it again.
You should view this very recent video from the electrical engineer at Audioholics
also post #47 from ebslo
speaker cable length variation within any reasonable amount is NOT something to be concerned with
 

MrPeabody

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There is an important point about this topic that I don't think came through clearly enough. It is this: in order for the difference in speaker wire length to matter, the longer of the two has to be long enough to have an audible effect via affecting the behavior of the crossover. If the longer of the two is too short to have any audible effect, then neither of them will have any audible effect, and any difference in length is unimportant.

The question of how much longer one cable can be vs. the other cable is the wrong question. The right question is how long either of them can be without affecting the sound.
 
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