Bi-wire: is it worth it?

Bifwynne, getting custom jumpers and only using half of the Kimber 8PR would not be a fair test. A quick easy way to eliminate bi-wire is to install the jumpers with the 8PR connected as it is now. If you could use a short piece of quality wire to do this, that should be better than the straps. Nevertheless, that will eliminate bi-wire for a comparison.

@Kijanki, IMHO your back EMF explanation is the only plausible one I have heard for why it would be beneficial to bi-wire.

However, I wonder then what the point is of bi-wiring with a cable that has all for wires twisted and wrapped in the same sheathing. Wouldn't the individual runs need to be separated in order to fully isolate them from EMF interactions?

Nick_sr, I don't know - inductance is inductance in any configuration but there are different and often strange findings. I've heard, for instance, that shorting positive (red) of upper and lower speaker in biwired speaker changes the sound. I have tried it and it does, but the only explanation I can come up with is that it removes half of the inductance from divider. Change was very small and I don't remember if it was for the better or the worse. It must've been for the worse since I rejected idea.

I have a pair of Mirage M5si's. They're bipolar 6-1/2" 2-ways, with matching pairs firing forward and backward. These speakers respond to every improvement in amplification and cabling you can throw at them.

My first wife could IMMEDIATELY tell if they were bi-wired or not. Even if they were biwired poorly, she noticed it within a coupld or seconds. When I didn't have the money for matched biwiring, I combined a set of solid core TARA Labs with some Straightwire 8-conductor ribbon cable. One night after everyone had gone to bed, I fashioned some better-than-factory jumpers from some Vampire Wire. I figured the matching cable should be better than such disparate runs to the woofers and the tweeters.

The next morning, as soon as my wife turned on the system--*to watch TV*--she immediately said, "Change it back; whatever you did to the system, change it back to what it was before." It wasn't even music; it was a talk show over cable, not a $40 audiophile recording, and yet she heard the difference immediately.

A year later, I upgraded the wiring to two pairs of MIT-750 and got a nice improvement in smoothness, linearity, clarity, etc.

Six years after that, Audio Advisor was blowing out the last of PS Audio's foray into premium cables, and I picked up a $1500 pair of XStream Reference Bi-Wire, the only cable up to that time that had been designed from the ground up specifically for bi-wiring. It uses 6-gauge copper for the woofers and multi-strand silver-plated copper for the high frequency input. These made a dramatic difference and were icing on the cake. Before, the M5si's always sounded like big speakers, but the PS Audio bi-wire rig enabled them to scale up and down better, and particularly improved the transparency and intimacy of the presentation. A friend of mine who is no audio geek, but who heard the system before and after the switch remarked how the new cable made the speakers compete with the immediacy and intimacy of minimonitors, which they couldn't do before.

Of course, YMMV. I suspect that when first order crossovers are used, there's less need for bi-wiring, but with more complex crossovers using combinations of 2nd, 3rd, and/or 4th order crossovers, biwiring asserts an advantage.

Biwiring makes a consistently difference with my Mirages, but my Magnepan 1.7s don't offer bi-wire inputs, and frankly, I'm really happy with the sound as-is.

I run Vandersteen 5s with complete double bi-wire (DBW) cabling so I guess I can't be objective. That said, there's a great article on the Vandersteen site about this topic and I have pasted an excerpt below. For me, the operational phrase is:

"Coupled with a crossover designed specifically for bi-wiring. . ."

Having spoken with Richard V. First hand, for my money he is an unimpeachable source of real-world intelligence, but others may feel differently. At any rate, here is the excerpt which I have edited for brevity (but changed no words--just deleted some sentences).

Bi-wiring uses two separate sets of speaker cables to connect a single pair of loudspeakers to an amplifier. Coupled with a crossover designed specifically for bi-wiring, it offers many of the advantages of bi-amplifying the speakers with two separate amplifiers without the cost and complexity of two amplifiers.

We began experimenting with bi-wiring back in the early '80s, an era when horizontal bi-amplification was considered the ultimate way to drive quality loudspeakers. (Horizontal bi-amplification used one amplifier to drive the low-frequency section of a speaker and a second amplifier to drive the high-frequency section.) We noted that speakers sounded better when bi-amplified by two amplifiers than when driven by a single amplifier. Surprisingly, this superior performance was evident even when the speakers were bi-amplified by two identical amplifiers at a low volume level and the amplifiers were each driven full-range without an electronic crossover. We initially believed that the double power supplies and other components of two amplifiers were responsible for the improvement, however building amplifiers with twice the power supply and doubling-up on other critical components failed to provide the bi-amplification benefit.

So we looked at the speaker wires. With two amplifiers, bi-amplification used two sets of speaker cables so we experimented with doubling-up the speaker wires and with larger wire. Neither duplicated the bi-amplification improvements. Then we considered that in a bi-amplified system, one set of wires carries the low-frequencies and the other set of wires carries the high-frequencies. We modified a speaker's crossovers to accept two sets of cables and present different load characteristics to each set so that the low-frequencies would be carried by one set of wires and the high-frequencies by the other set of wires. Finally we heard the sonic improvements of bi-amplification with a single amplifier.

Additional experiments with a Hall Effect probe revealed that high-current bass frequencies created a measurable field around the wires that expanded and collapsed with the signal. We believe that this dynamic field modulates the smaller signals, especially the very low level treble frequencies. With the high-current signal (Bass) separated from the low-current signal (Treble) this small signal modulation was eliminated as long as the cables were separated by at least an inch or two. (To keep the treble cable out of the field surrounding the bass cable.)

The crossovers in Vandersteen bi-wirable speakers are engineered with completely separate high-pass and low-pass sections. The bass inputs pass low-frequencies to the woofers, but become more and more resistive at higher frequencies. The treble inputs pass high-frequencies to the midrange and tweeter, but become more and more resistive at low-frequencies. The output from the amplifier always takes the path of least resistance so deep bass frequencies go to the bass input (Low impedance at low-frequencies) rather than to the treble inputs (High impedance at low frequencies). For the same reason, treble frequencies go to the treble input (Low impedance at high-frequencies) rather than to the bass inputs (High impedance at high-frequencies). At the actual crossover frequency, the output from the amplifier would be divided equally between the two inputs as they would both have the same impedance at that frequency. Because of the different reflected impedances of the cables, the crossover between the woofer and midrange actually occurs at the wire ends where they connect to the amplifier.