Uneven speaker wire runs

My equipment sits to the far right side of my home theater setup. I need at least a 21 ft. run to the left speaker and the right would only need about 10 ft. Does it matter if the L & R main speaker runs are different lengths or should I try to keep them the same ?
I doubt you will hear an audible difference. Electric signals travel at close to the speed of light and speaker cables do not filter the signal very much (unless you have a mis match between speaker impedance and amp output impedance...for example a 4 ohm speaker with a tube amp of high output impedance).
Since the signal is traveling @ roughly the speed of light, the 11' difference is irrelevant.
For home theater, perhaps it wont matter as much. Usually that equipment had some compensation control that can be used for unbalanced sound.

For serious 2 channel, Yes, it does matter, big time.
Keep them as close to the same length as possible.

It's odd, isn't it, that an audio signal doesn't travel at the speed of sound.
Equal length cables are easier to re-sell later.
It doesn`t matter a whit in 2 channel either. 186,000 mi./sec. divided by 11 ft. Do the math. The laws of physics are the same for HT or 2 channel.
Tarsando, an "audio" signal doesn't travel the speed of sound when it's in the wire because it's an "electrical" signal at that point. It doesn't become an audio signal and travel at the speed of sound until the electrical energy is converted into acoustical energy at your speakers. I think you knew that however.
The possible difference doesn't have anything to do with the speed of the signal but POTENTIALLY with the inductance,resistance and capacitance of the cable.
In reality it's probably fine!
What kind of cables and how much are you spending? If you're going to buy bulk wire at a couple of dollars a foot and have them terminated, then it's not a issue for resale or buying. If you're looking at name brand or expensive, it might be tough buying them in uneven pairs. And what if you moved your gear at a later date - you'd have uneven cables again. It's always more practical to buy in even lengths.

As far as performance goes, that extra length will result in an uneven voltage drop from each channel to the speakers (ALL wires have a resistance per unit length, speed o' light notwithstanding). The effect of an extra 11 feet would be the same as having two speakers with equal cable lengths but with one speaker set further back a fraction of an inch. It's trivial IMHO.
Hey, MarkPhd, I did know that. I was just commenting on how odd it was--not as odd I guess as worrying about a few feet of speaker cable plus or minus.
I am thinking of buying ViaBlue SC4 cables. The reason I asked is that they can be ordered in various lengths hence the question about whether I should keep the mains the same. Never really thought about it before but I am setting up my system in a new house. Nautilus 802 driven by Lexicon 2x250 amp, Lexicon DC-1 processor.I plan to upgrade to Lexicon MC-8 or MC-12 and Bryston 6B SST. Reference:
Just throwing my 2 cents in. I would keep the lenghts the same for the technical reasons mention above. While you may not hear the difference why wonder if you are missing something. Plus resale will be easier. I purchased speaker cables a little longer than I needed just in case I ever wanted to sell them I would have a standard size. I have N802's and would be curious to hear how they sound with the 250 watt lexicon amp. I found mines don't really sound good unless I pair them with high current amps capable of pushing 300 - 400 watts per channel. A friend has the new diamond N802 paired with a Theta which delivers 250 per channel. Despite what the dealer told him they are no where near as open and full sounding as mine with 480 wattsr
It's not the delay that can make a difference but other factors such as capacitance and impedance that can add up in cable length. I wouldn't recommend using 21' speaker cables at all. If you must, use low capacitance (teflon dielectric) 12 gauge wires, or more. You can also look at Ultimate Cables which is willing to do custom orders.
If you are going to the trouble of bi-wiring (dubious from an engineering perspective if this will make an audible difference given a low impedance SS amp driving your speakers) then I would go for exactly the same length wires to be safe (after all you are spending a lot of money - so why not spend $200 more and eliminate any doubts/worrries)
Keep the wires the same length, use 10awg and if you bi-wire make them a true bi-wire. Two seperate runs. Impedence, inductance and capacitance needs to stay consistant and to do this the wire needs to be the same length. The amp has a different effect when the variables of the wire changes. Two 10awg speaker wires from two differnt mfg's will most likely sound different but the bits and pieces may travel at the same speed with some of the bits and pieces getting smeared along the way. It's like comparing the speed of your thoughts to your vocals with a major hangover to the speed of your thoughts to your vocals without the hangover. Somehow there is less smearing when sober. Believe me, you don't want to start talking about skin effect.
Just a point of order, audio signals don't travel at anywhere near the speed of light. Only light in a vacuum travels at 300,000km/sec. Even light travels at less than this depending on anything (eg. gases) it must pass through.
The speed of an electric current is dictated by various things including resistance; lightning through air only travels at around 160,000km/hour, not even close to lightspeed.
Audio signals travel by electrons being "bumped" along through the copper or silver crystal lattice, at nothing like lightspeed.
My view would be that, if you had one 1000 foot speaker cable and one 10 foot, you would notice an obvious timing error, a delay if you like. Now, 20' versus 10' isn't quite the same degree, but the effect will still be there at a much smaller delay. I don't think I could hear such a delay, but some keen-hearing audio buffs might.
Carl, do the math. Even at the slow 160000km/hour speed of lightening, one wouldn't detect the difference in arrival (or delay) between 1000ft and 10 ft cable. Don't you just love mixing units of measure?!!
Ozzy is right, if it is for home theater you probably would not notice the tonal balance difference. Plus you could set up your pre/pro to compensate if you heard a difference. In a good two channel setup you can hear it. Especially in the vocals. Good thing that most of the vocals will come from the center channel of your HT.
Thanks for the input. I remeasured and can get by with an 18 ft. run so I decided keep the L/R mains the same. I found a chart on the Revel speaker website and this length should be fine with 11 AWG wire. Their chart gives a max length for each size wire to maintain a loop resistance of .07 ohms or less. My B&W owners manual recommends a max cable impedence of .1 ohms so I should be well within these parameters.
I can't find much info on the wire I am going to use (ViaBlue SC-4) but I was looking for a wire that addresses both high and low frequency issues for a bi-wire configuration. According to what info I have found this silver/copper hybrid should work well for my home theater setup. I also found a website that will give me a very great deal on the wire.