William Eckle wrote:

The following is a statement by Robert Harley in the current issue of
"The Perfect Vision".
Quote:

Connecting your speakers with two runs of loudspeaker cable
(if your speakers have two sets of input terminals) provides
a small but significant improvement in sound quality.
One pair of the speaker's input terminals is connected to the
woofer,and the other pair to the midrange and tweeter (or just the
tweeter in a two-way speaker). In a bi-wired system, the power
amplifier "sees" a higher impedance on the tweeter cable at low
frequencies and a lower impedance at high frequencies. The opposite is
true on the woofer half of the bi-wired pair. This causes the signal
to be split up, with high frequencies traveling mostly in the cable
driving the tweeter circuit, and low frequencies conduced by the pair
connected to the loudspeaker's woofer circuit. This frequency
splitting reduces magnetic interaction in the cable, resulting in
better sound.
If you have the ability to bi-wire, it's worth the cost of an extra
run of speaker cable. You can buy bi-wired cables with a single pair
of terminations on the amplifier end and dual termination pairs on the
speaker end. Be sure to remove the "jumpers" that connect the
pairs of speaker input terminal.
Unquote.

Is this true about the amp seeing the differences in impedance ?
And is it audible ?

================================

To me the key paragraph, where all the important information in this
post is found, is:

One pair of the speaker's input terminals is connected to the
woofer,and the other pair to the midrange and tweeter (or just the
tweeter in a two-way speaker). In a bi-wired system, the power
amplifier "sees" a higher impedance on the tweeter cable at low
frequencies and a lower impedance at high frequencies. The opposite is
true on the woofer half of the bi-wired pair. This causes the signal
to be split up, with high frequencies traveling mostly in the cable
driving the tweeter circuit, and low frequencies conduced by the pair
connected to the loudspeaker's woofer circuit. This frequency
splitting reduces magnetic interaction in the cable, resulting in
better sound.

================================================== ===

Up to the last sentence, it's all true, assuming a passive crossover in
the loudspeaker that actually behaves as described (not all of them do).
That last sentence is the one where unproven assumptions are used by
Mr. Harley to come to a conclusion. Those assumptions include the
actual existence of magnetic interaction, its amount, and the true,
audible effect of such "interaction."

Acceptance of those assumptions results in Mr. Harley's recommendation,
where he makes a value judgment that rightfully belongs to the buyer:
"If you have the ability to bi-wire, it's worth the cost of an extra run
of speaker cable." Given the price of speaker cable that Harley's
magazine would recommend, I'd find the money better spent on more
software...that is, more music to listen to; at the price of that wire,
a LOT more music. But that's MY value judgment.

-GP