FreeRadical
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First Bi-Wire Speakers, Now What?
ethanwiner
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Quote:
Should I biwire, and if I do what are the benefits and drawbacks?


Bi-wiring offers no improvement, though some people seem to believe it does.

--Ethan

BillB
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I have Vandersteen speakers and the manufacturer strongly recommends bi-wiring. Since Vandersteen doesn't market cables themselves, and since Mr. V. is reportedly a solid and well-grounded designer, it's not unreasonable to me to consider that there may be a benefit.

I haven't tested it myself. When I went from single wire to bi-wire, I also changed the brand/type of cables, so can't compare the single variable. (The new cables did make a small, positive difference, FWIW.)

Jan Vigne
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I would think the Focal dealer would have cables they feel work well with their speakers. Ask for a loaner pair to audition the benefits of biwiring with your speakers. Some speaker/amplifier combinations will benefit from splitting the crossover and some will not. Some speaker manufacturers sell biwired speakers simply because buyers expect them to. Ask your dealer for a loaner pair of cables and decide for yourself.

Elk
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Some speaker manufacturers sell biwired speakers simply because buyers expect them to.


John Dunlavy was one. There are quite a few others.

I've never had the chance to experiment with two sets of identical cables to see if bi-wiring makes a difference.

That said, I am using a set of bi-wire cables which I like. I have no idea what they are like single-wired however. I got them at a great price and have been pleased with them so I haven't experimented beyond this.

The circuits are electrically identical whether bi-wired or single wired. Thus, it should not make any difference.

Jan Vigne
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The circuits are electrically identical whether bi-wired or single wired. Thus, it should not make any difference.

I don't believe that's exactly true. In a well designed crossover the circuits would be electrically identical in single or biwire configuration which is why many designers such as Jim Thiel don't bother with biwiring. In a crossover intentionally designed for biwiring the ground plane for both drivers is broken into distinct signal return paths so there is no commonality between the high pass and low pass sections of the filters. The intention of biwiring in this configuration is to keep the back EMF of the woofer out of the signal path of the mid/tweeter. The electrical load on the amplifier should remain the same as a single wire setup but the tweeter in many biwire speakers does not see the same signal in biwire as in single wire. If the crossover is wired in this fashion, the speaker should also be capable of being bi-amped through the passive crossover components.

Elk
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Interesting point.

But if we trace the circuit back tot he amplifier outputs where the two sets of speaker wires come together, the two separate crossovers are again connected. True, this happens further away from the speaker than if this connection is at the crossover itself, but the same electrical influences are at play in either configuration.

Why would this make any difference? I don't think the bass carrying electrons are clever enough to know not to go* down the tweeter cables. Or are they?

(*Yes, I know wave propagation theory and how electricity is actually low energy photons transfered between outer shell electrons and that the electrons themselves don't really go down the wire.)

Jan Vigne
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Why would this make any difference? I don't think the bass carrying electrons are clever enough to know not to go* down the tweeter cables. Or are they?

No, and that seems to be the main point of biwiring. If you think of the back EMF current as the proverbial water flowing through a pipe, you can then consider what happens when a straight line (running through the return line of the woofer) meets a junction with one side running back to the amplifier and the other to the mid/tweeter. The EMF stream doesn't know it's supposed to only head toward the amplifier and some amount of EMF created by the woofer is diverted with a portion heading toward the the amplifier and some portion heading toward the tweeter. When this occurs the tweeter's signal is also carrying a bit of the woofer's EMF signal which is slightly out of phase wih the actual signal sent to the tweeter from the amplifier. I would assume the more complex the crosover the more destructive this effect would be. Therefore, depending upon the crossover and the amount of current off the woofer, the tweeter's smaller signals can to a degree be swamped by this out of phase EMF current. The tweeter is then seeing signals that 1) should never be on on the high pass circuit and 2) results in a portion of the woofer's back EMF eventually arriving at the amplifier's global NFB input out of phase with the original portion of the EMF signal from the woofer. Since anything that is not similar to the original signal is discarded by NFB, the amplifier sees a poor representation of the input (with information smeared in the time domain) at the output side of the NFB circuit. Placing the junction point of the highpass/low pass circuits closer to the amplifier's NFB input (the speaker terminals themself) should reduce the amount of leakage to the tweeter and presents a more complete signal at the NFB inputs. None of this is on a macro scale but this is, as I understand it, the theory of why and how biwiring can improve the sound of an amplifier/speaker combination. Following that logic the more the amplifier relies on global NFB for it's sound quality and the lower the quality of the crossover layout, the more problems the biwiring approach can resolve in the circuit thereby increasing both bass drive by maintaining a more consistent damping factor and more information retrieval from both the amplifier and the high frequency side of the crossover. This makes the amplifier a portion of the equation when discussing the benefits of biwiring any particular speaker.

Of course, the benefits of passive bi-amping are another matter.

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