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RE: I think Richard Vandersteen got it right

The magnetic field established at right angles to a current flowing in a conductor is the Hall effect.


No it isn't. That's Ampere's Law.

But the inverse is also true: a changing magnetic field can cause a current to flow in a conductor.


And that's Faraday's Law. You are right that the two cables in a bi-wire configuration will interact via their magnetic fields. This is normally just called crosstalk and doesn't require the Hall effect. The Hall effect is something different, see the Wikipedia page linked below.

I think RV is making a reference to Faraday's Law and crosstalks, but his explanation doesn't work. First, a time varying magnetic field produced by current flowing in one conductor can induce EMF in another conductor, but it's a moot point in biwiring because both conductors are already being driven with the full range single at the amp. Second, the high pass filter portion of the crossover is blocking low frequency currents from flowing through the tweeter, and it doesn't care if the low frequency EMF is coming from the amp, from cable crosstalk, or from the hair dryer in the next room.

The only frequency range where the low frequency and high frequency networks interact is in the crossover range where the low pass and high pass filter responses overlap. In this frequency range, back-EMF from the woofer is the main source of unwanted EMF affecting the tweeter. In the bi-wire configuration, the back-EMF can be sunk by the amp with less effect on the tweeter output.

Also, in this frequency range, the magnetic interaction between the two biwire cables manifests itself as a change in their combined impedance as seen by the amp.

One other difference between single and bi-wiring is increasing the parallel capacitance of the cable (doubling it if identical cables are used).

So there are at least three basic explanations to explain why biwiring might produce different results: damping of back-EMF, changing the effective impedance in the crossover range, and increasing parallel capacitance.



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