Here is something I posted on another forum about this subject. It might be relant here . . .
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Currently I have my b&W speakers biwired. I could not tell the difference in sound,
so didn't go to the trouble of making them single wired again.
In *theory* there is an advantage to biwiring. As somebody above pointed out, one of the reasons people cite for using biwiring is the potential problem due to "back emf" from one driver affecting another driver. When a speaker driver moves it can generate an electrical signal (much like a microphone does). Lets consider a possible situation. B&W recommends using a speaker wire with less than .1 ohm resistance. So, lets assume the speaker wire has .1 ohm resistance. We like to use amps with high damping factor, lets assume an 8 ohm speaker being used with an amp that has an 800 damping factor - i.e. the internal resistance of the amp is .01 ohm (as an aside note that any benefit of having extemely high damping factor for the amplifier is partially canceled by having to use speaker wires). Lets assume the bridging plate between LF and HF terminals of the speaker has resistance .01 ohm. In a biwire arrangement the back emf from one driver has to flow through the .1 ohm speaker wire, which reduces its amplitude, then most of it gets absorbed by the amp since it has much lower resistance than the wire to the other drivers (and of course the other drivers themselves). With a bridging plate the back emf from one driver is just .01 ohm and a crossover away from the other driver. So, more of that back emf will reach the other driver in a single wire configuration than in a biwire configuration. There are a couple of obvious weaknesses to this arguement; one is that back emf is very small to begin with compared to the amplifier signal. Another is that the resistance of the other driver is larger than the speaker wire so most of the back emf will go back to the amplifier anyway. But the fact remains, that in a biwire arrangement less of the back emf from one driver will reach the other drivers in the speaker (although this difference will be very small, sometimes, perhaps, small is enough).
Another argument sometimes made is that the voltage drop across the speaker wire due to large currents needed to drive a woofer will impact the sound of the midrange/tweeter. 20 amps flowing through .1 ohm speaker wire does result in a voltage drop of 2 volts - not huge, but easy to measure. Of course, a voltage drop at 40 hz (for example) should not effect the midrange/tweeter at all. But what about at the frequency near the crossover? Lets say the woofer crosses over to the midrange at 350 hz. At this frequency both drivers make sound and use energy. Perhaps voltage drop near the crossover frequency could effect one driver or the other. For example, lets say the amp was pushing 10 amps at 350 hz - the voltage drop across a single .1 ohm wire would be 1 volt, now instead if we biwire, and assume that half the current goes down one wire and half down the other wire, there is only a .5 volt drop. (of course if we just used both wires together the total drop would still be only .5 volts since the resistance of the doubled up wires would be half of a single wire - but maybe, just maybe, there could be some strange interaction between drivers at the crossover frequency that gave an advantage to a biwire arrangement - it is not completely impossible. . .)
To say that biwiring is EXACTLY the same as running a single wire then bridging the speaker terminals is just WRONG! If wires had zero resistance they would be exactly the same, but alas, all wire has some resistance. While I haven't tried it I am absolutely positive that if I hooked up a scope to each end of a speaker wire I could measure a voltage across that wire. I am also positive that if measured the voltage drop across a biwired speaker, each wire would measure a different voltage drop. What I'm not positive about is if the difference between the voltage drop across a single wire would be measurably different than the sum of the voltage drops across a biwired pair. There would be a difference, but I'm not sure how easily it could be measured - I guess it would depend on the sensitivity of your equipment, I'm sure it could be measured if somebody really wanted to try.
So why did I even bother trying biwiring? Well after 20 years my old speaker wire was getting somewhat corroded. Though I could (and did) clean it up, since I had just got new speakers and amp I decided what the heck I'll get some new wire as well. My wire of choice was canare 4s11 - it is relatively cheap, well made, and has decent gauge. It also has 4 conductors so trying out biwiring is simple. I'd read some things saying biwiring was better, and others saying it made no difference. I figured I try it for myself. I could not tell the difference between single and biwire, but, since I tried single wire first I just left it biwired. . .
I think maybe some people hear a difference between cables just because they went from an old partially corroded connection to a nice new clean conection (probably not a big deal at speaker voltages, but, certainly could be at phono cartiridge levels)
Perhaps Kal can have his measuring guy at sterophile see if a difference can be measured. Perhaps he has already tried and determined the difference is small and hopefully negligiable, perhaps he is afraid to try for reasons unknown.
There are people who think speakers wires sound different. I can see in this case that those people would want to select a wire that does "better in bass" for the bass driver, and a wire that does "better in midrange/HF" for those drivers. Once I thought I heard a difference in speaker wires, but, when I went back to try again I could not pick it out again - perhaps just switching wires (and at least partially cleaning the connection) made the difference, or maybe I'm just half deaf (wait I'm almost 50, have been listening to music for more than 40 years, so might actually be half deaf - tho last time I had it check I was normal for my age, there is no doubt that I do not hear some high frequencies I used to hear, which is normal)
It is ironic and unfortunate that by the time you can afford fast cars and great stereos, that your reaction times have gone down, and your hearing has degraded, so you cannot really enjoy either to there full potential . . . But I can still enjoy both to my full potential which is good enough I suppose.
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Some additions specific to this thread.
Maybe I did not hear a difference because my trebble and bass wires are
nearly colocated (I use the canare quad wire). Perhaps if I'd have used seperate wires I'd notice a difference (but to be honest I doubt it)
While voltage is applied equally at the amplifier end of the wires, the crossover at the end of those wires prevents current from flowing except in the frequencies the speakers will use. It is current flow that drives the speakers, and, any emf that might influence sound.
In the end I continue to think that wires make very little difference in sound, unless the wire is somehow defective, or specifically tuned with excess capacitance or inductance.
