Some speaker manufacturers provide for bi-wiring, some do not, and a few of those that don’t seem pretty dismissive of the whole idea.

It sure works for me! When I built my current speakers (details below) I made them bi-wirable so I could mess around with it. I expected to make extensive listening tests, but the difference was so obvious that I decided in five minutes that bi-wiring was better, in my case at least. Bi-wired, the speakers were much more dynamic, and the sound opened up spatially in the most remarkable way. It was not close.

So I wonder two things: 1. Why does bi-wiring work? I’ve read several explanations, the most plausible of which (to me) is that it lets less of the woofer’s back-EMF into the tweeter.

And 2. Why do some speaker manufacturers downplay the efficacy of bi-wiring? Is it because bi-wirable speakers are by definition bi-ampable, too, and they’d rather not give their customers the ability (in a horizontal bi-amp setup) to change the tonal balance of their products? Or could some kinds of speakers sound worse when bi-wired?

TIA, gents!

Mark

[FYI my home-brew speakers are smallish, 2-way, sealed-box units with 6” paper-cone Vifa woofers and cloth-dome Scan-Speak tweeters. Crossover is 1st-order at 2.8 kHz, and there is a Zobel network on the woofs. Bass alignment is somewhat over-damped, Q = ca. 0.63.

The wires are 24’ runs of Sound King 10G. Level-match was checked with a volt-meter. The wire was not doubled-up for single wire listening, I just discoed the tweeter wires and strapped the terminals together.]

 Re: Why Bi-wire? - TomWh 06:30:13 08/14/03 (0)
 Ok, so here's my theory... - Commuteman 15:51:19 08/12/03 (4)
 Re: Ok, so here's my theory... - Jon Risch 10:32:46 08/14/03 (2)

...

Show full thread outline!

 Re: Why Bi-wire? - TomWh 06:30:13 08/14/03 (0)
 Ok, so here's my theory... - Commuteman 15:51:19 08/12/03 (4)
 Re: Ok, so here's my theory... - Jon Risch 10:32:46 08/14/03 (2)
 Many thanks, Jon nt - markrohr 09:01:57 08/15/03 (0)
 Nice job - Commuteman 14:30:53 08/14/03 (0)
 Re: Ok, so here's my theory... - john curl 16:29:55 08/12/03 (0)
 'Cause It's Unlawful to Steal Wire... - Todd Krieger 08:45:38 08/12/03 (9)
 doesn't superposition contradict this? - Commuteman 16:23:53 08/12/03 (8)
 Not when there is another factor - Jon Risch 10:31:13 08/14/03 (2)
 this seems more likely - Commuteman 14:41:24 08/14/03 (1)
 Re: this seems more likely - Todd Krieger 15:15:22 08/14/03 (0)
 Re: doesn't superposition contradict this? - dave slagle 19:12:35 08/13/03 (1)
 Yes, superposition does contradict it. - jneutron 10:08:37 08/14/03 (0)
 Re: doesn't superposition contradict this? - Todd Krieger 21:25:10 08/12/03 (0)
 Re: doesn't superposition contradict this? - Lymp Baygul 19:57:27 08/12/03 (1)
 So Spectron Remote Sense technology obviates the need for biwiring...? - Rob Thomas 22:24:13 08/17/03 (0)
 Re: Why Bi-wire? - Steve Eddy 11:10:41 08/11/03 (0)
 DId wonders for my system!nt - NEAR SOTA 09:32:25 08/11/03 (0)
 Re: Why Bi-wire? - Charles Hansen 09:12:58 08/11/03 (5)
 Re: Why Bi-wire? - markrohr 06:54:55 08/12/03 (2)
 Don't despair.... - Charles Hansen 08:31:52 08/12/03 (1)
 Thanks--just kidding, actually nt - markrohr 08:53:17 08/12/03 (0)
 Re: Why Bi-wire? - john curl 19:38:37 08/11/03 (1)
 I'm not sure... - Charles Hansen 21:21:56 08/11/03 (0)

Enjoy Tom

Bi-wiring avoids any interactions between currents (and attendant fields) of the high- and low-pass sections of the speaker because the two sections only meet at (or near) the place where the amp can exercise control over the signal. In other words, the only wiring common to woofer and tweeter is now inside the amp's feedback loop.

Single wiring allows currents flowing to and from the woofer (actually to the low-pass xover section) to modulate the signal presented to the high pass xover section because the cable has a non-zero impedance.

I'm still not convinced this is right, so I need to think about it some more....

Perhaps there is an analogy to good grounding techniques. I was taught to do the thought experiment of putting a small resistor in place of every ground connection in a piece of electronic equiment and looking at the ways in which things like capacitor charging currents can modulate ground voltages.

Peter

See:
http://www.geocities.com/jonrisch/biwiring2.htm

Jon Risch

Peter

• http://groups.google.com/groups?selm=33948A4D.11F4@ix.netcom.com

That's what I'm still struggling with -- a credible explanation for the interaction between HF and LF signals in the cable.

Doesn't mean I think it doesn't happen -- just that I can't explain it to my own satisfaction (yet).

Peter

The current through the two bi-wire sections is different, and so the cable carrying the HF current will not get motor/generator modulated by the LF currents.

Current flow in the two bi-wire cables in a simple 2nd order crossover is shown at:
http://www.geocities.com/jonrisch/page7.htm

The other factor that I think bi-wiring addresses, is that of woofer to tweeter isolation, and I go through this aspect at this page:
http://www.geocities.com/jonrisch/biwiring2.htm
and the following one.

Jon Risch

The acoustic coupling of the drivers you described is the first explanation I have seen of driver A affecting driver B in the frequency range that driver B produces.

In other words, the acoustic output of the tweeter causes the woofer to act as a motor for signals within the tweeter's freq range. This would clearly cause a delayed, distorted version of the original signal to be reproduced by the tweeter.

The magnitude of the effect would be dependent on the xover topology. As an extreme case, there are some speakers that have no low-pass xover on the woofer. In that case, the full magnitude of the induced signal would be driving the tweeter xover, in parallel with the cable and amp impedance.

Fascinating.....

Sounds like time for an ABX test to prove we can't hear any of this.. ;-)

Peter

the change in resistance is quite trivial by the math with the audible frequencies we are concerned with... but amps of current through the trivial could add up to something. (see crossover coments elsewhere in the thread)

you also say "can travel" is that the same as "does travel"??? just tryingto get the 99 cent physics lesson i slept through in highschool wondering "when will i ever use this junk"

now histery and english... them was naps well spent.

dave

For a wire, when skin effect occurs, the current will be excluded from the wire interior, in gradations of course.. So, a skinning current will have no internal inductance, hence no energy storage. Whereas, the lf info does not, and does have internal energy storage.

If an audio lf signal is pulled across zero by a hf signal, the internal stored energy will be pulled out by the slew rate of the hf information..it is not clear yet if that released energy is consumed in the re-distribution of the current density profile, or if it reacts externally, possibly time shifting the leading and trailing edges of the hf information, thereby blurring the interpreted soundstage. That would require time shifts in the 5 to 20 microsecond realm.

See, that wasn't so hard, now was it??

Cheers, John

I am not aware if anyone has tried to compare speaker cables with low and high inductance to see if the effects of bi-wiring are dependent on this. I would think a braided design such as Kimber Cables would not show as signifigant a difference as straight designs do.

The liniear inductance of cable is also why fancy power cables do what they do.

...by sensing for the feedback loop at the speaker binding posts?

• http://www.spectronav.com/cables.html

Dunno. Haven't seen any explanation thus far which has made much sense.

Though some time back when I started tinkering with solid state single-ended amplifers which often use a large electrolytic output coupling cap or caps to block the DC offset of the amp, I saw that bi-wiring could afford the opportunity to bypass the main output coupling cap(s) and drive the high-pass section directly from the amp's output.

That's about the only scenario that's made any sense to me at least from a technical perspective.

se

I've also had excellent results with bi-wiring. Here are some reasons that some manufacturers don't recommend it:

1) The speaker in question uses a series crossover and cannot be bi-wired.

2) If you use anything except identical wires, the performance of the speaker will be altered in unpredictable ways. There are too many ways the end user can screw things up with bi-wiring.

3) The manufacturer recommends silly expensive speaker wire and if you bi-wired with that stuff, the wire would cost more than the speakers.

4) The designer is deaf and can't hear the difference between different speaker cables OR bi-wiring.

You can probably guess which manufacturers fall into which of these categories.

Best regards,
Charles Hansen

I forgot about series crossovers. I had thought they might be pretty rare in production speakers since they must be a pain in the neck--or at least incredibly time-consuming--to develop.

I hope more will chime in on why bi-wiring works.

Thanks again,

Mark

In other words, don't throw out the baby with the bath water. There are already enough people on this forum that do that already. We don't need any more.

Best regards,
Charles Hansen

Best regards,
Charles Hansen