To bi-wire or not to bi-wire?

Biwiring is explained scientifically on the Vandersteen website

A theory is proposed...low frequency high power signals induce noise on high frequency low power signals. It is hardly science though.

Given the low impedances of speaker loads and amplifier outputs it seems unlikely that noise can be induced in speaker wires that would be at all audible.

Of course, there is some ground truth, if you run unshielded line level signal wires next to some AC power cables feeding an airconditioner then it is quite likely you will pick up some noise...but this is because of the very low levels of signal at line level and the fact that termination impedances are around 10K Ohm - meaning that tiny stray induced currents may actually produce audible noise - even allowing you to pick up interference from a radio station or a ham radio perhaps..

A more logical explanation for reported observations may be caused by unecessarily wide bandwidth amplifiers of the sort that amplify flat up to 200 KHz - instabilities in amps of this type (with large amounts of feedback) might be affected by the slight change in cable inductance that biwiring would bring versus a conventional speaker wire. (Why anyone needs an amp flat to 200 KHz for audio reproduction is rather bewildering, however, specifications like this might make a buyer think the amp is "better" than one which rolls off above 20 KHZ - so they sell - the same way that damping factors of 1000 sell...)

I've found the differences to be subtle, even with separate runs. However if you're after the best sound possible and the $ is inconsequential it does make an improvement (IMHO). If you're on a budget, you should evaluate whether that $ could make a bigger impact elsewhere in your system.

As to the idea of the amplifier seeing a different impedance from biwiring vs not biwiring, any way you draw the circuit, the amplifier sees the same impedance. Likewise, biwire or not, both drivers see the same signal from the amplifier. Shardone's transmission line theory offers a plausable explanation for changing the impedance as seen by the amplifier (at high frequencies) but does not provide for an explanation as to a difference in the individual speaker circuits as seen by the amplifier- in other words the change is macro affecting everything. Now, the induced noise theory offered, from coupling low frequency noise (probably 60 Hz) does offer a plausable explanation for different effects on the respective drivers, assuming that the coupling is different for each set of wires, because that theory essentially inserts different sources in each leg (Nice theories by the way) I don't think this is the intended goal of biwiring though. I checked out all of the online explanations of the biwire effects that I could find but could not find one that demonstrated the effects through an analysis. If there is an explanation why not show it with a step by step circuit analysis with reasonable lumped components - i.e. not assuming that the speaker wires are ideal conductors. That is how the rest of the engineering community explains such things. Seems easier and more convincing. Kind of hard to argue with math (actual math that is, not referrals to math terms).

Thank you all for your responses. I have a 50' spool of inexpensive 14 gauge wire. I'm going to take the Audience Au24s off the Dalis and make up 4 cables for a bi-wire experiment.

Markphd - what is "passive" bi-amping?

I would like to add 2 other reasons. One is skin effect that starts at gage 20 at 20kHz. Many woofer cables use gage 7 to preserve low impedance (damping factor). Second reason are the Eddy currents, generated by speakers, getting from speaker to speaker (tweeter to midrange or midrange to tweeter) in spite of crossover (far from perfect) and amplifier's output impedance separated by (inductive 0.5uH/ft) impedance of the cable (equal to about 0.5 Ohm at 20kHz = 1/10 divider with speakers source impedance). Effects are very small but remember incredible range of our hearing instrument. Bi-wiring creates divider of the mentioned 0.5 Ohm cable impedance and very low amplifiers output impedance. Amp's output impedance of 0.05 Ohm at 20kHz will create 1:100 divider with speaker impedance before it gets to the other speaker - 10 fold improvement.

My speakers are bi-wired with a shotgun cable and sound slightly more "airy" in comparison to non-biwired (shorted terminal). Is it worth to pay for that about double (of expensive speaker cable)? I don't know - probably not, but I treat cables as non-perishable items and over-invest a bit.

The fact that according to many users bi-wiring improves some speakers but has no effect on the others might be related to design (steepness and configuration) of the crossover.