Speaker Asylum General speaker questions for audio and home theater.

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Re: ?????

Posted by Kal Rubinson (R) on March 9, 2007 at 11:30:37

In Reply to: Re: ????? posted by Dave Kingsland on March 9, 2007 at 10:43:14:

Well, if you reduce the impedance of the cable to 0.1ohm (for argument), the effects you describe reduce to insignificance (even if I accepted them all).

Also, your example of the 4ohm speaker having 2 8ohm legs is unrepresentative. Both legs are usually 4ohms in their respective passbands and each defines the net characteristic impedance in its passband. (Sure, cabinet + resonance effects aside.)

So, let’s look, again, at your analysis:
You say that (keeping your 1ohm cables), “Using a single cable, the total impedance of the cable plus load is 5 ohms (1 + 8/2). When bi-wiring with two such cables, the total impedance is 4.5 ohms ((1 + 8)/2).” Each leg is a 4ohm speaker load and a 1ohm cable load and the result is a 5ohm load either way. The two parenthetical statements should be (1+4) and (1+4). The latter since each leg represents a meaningful load only in its passband. At crossover, there will be some reduction in overall impedance where the two legs are effectively in parallel but see below for comment on that.

“As a result, bi-wiring will produce an increase in speaker output in the frequency range where the crossovers overlap. It may not be big, but it can be explained and measured.”
And why, assuming it is true, would that be desirable? Surely, you would want the load and the output to be identical at all frequencies.

“One might conversely argue that a speaker which supports bi-wiring may have been tweaked or voiced by the designer to sound its best in a bi-wire configuration. But I have no idea whether this is common.” Well, unless the manufacturer explicitly states that the speakers MUST be used bi-wired, one must assume that bi-wiring is not necessary. I do recall that some Alon speakers were so specified but, since monowiring is almost ubiquitous, it would make sense to for a manufacturer to presume it.

I have been told, face to face, by several speaker manufacturers who ‘recommend’ bi-wiring in their user’s manuals that they provide such a facility to accommodate their dealers (who want to sell more cable) and some of their clients who wish to do it.

Now, I do not see any disadvantage to bi-wiring (heck, I use it) but I have not seen any convincing demonstration of “why” it is advantageous. And that “why” is what I responded to, not any issues of perception or preference.

Kal

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