Bi-Wire

[thepcguy]

www.sonicdesign.se/biwire.html

THE DISADVANTAGE WITH BI-WIRE

One thing that happens when you biwire your loudspeakers is that the input of the high- and the low-pass filters are fed with different input signals. The difference is a result of the high frequencies and the low frequencies being forced to travel different paths, perhaps through different types of cables, but under all circumstances through cables who have seen different loads (a tweeter with a high pass filter has a completely different impedance response compared to a woofer with a low pass filter!).

What happens is that the drivers will work less good together than when their filter halves were fed with equal signals. The result is a generation of more static and stochastic phase error sounds at different directions from the loudspeaker. The stochastic phase error sounds appear because there may be different types of unlinearities in the low- and high-frequency paths.

What does this sound like? Well, usually, just as you may expect from physics, it appears as a change in the reproduction of space and sound stage. Often, the first impression is that the "biwired" sound presents extended "dimensions", more "air", and is more "living". The impression after a week or month, however, is that all recordings sound very much alike, and the "airiness" appears on all records. It does not even sound like air anymore, instead more like a slime that pollutes every record you play. No wonder, since it is not a real, recorded quality but a "speaker characteristic" added to all reproduced material. "Sameness" is another word for it.



Picture 4: This simulation is based on the diagram of picture 3. Here you can see that a phase difference has arisen when biwiring is used. The reason why the phase difference is largest just above the cross over frequency is that the inductance of the cable resonates with the capacitance of the high pass filter when not the inductance of the low pass filter is available in this range as when single wire is used. The most probable reason to the capricious sound of biwiring is that on top of this steady state error another, transient induced phase error between the cables will appear when playing music. This changes the radiation pattern of the speaker with the music. The human ear is very sensitive to such phenomena.

[savjac]

Now this is funny... "a slime that pollutes every record you play"


I have actually tried this in my B&Ws and never heard a difference but I am not the world.
The newer speakers, do not have multiple bindings posts so no real need to try. I just use runs of single 10 gauge Blue Jeans and they work great.

I remember very clearly a conversation with one of the Quad speaker reps at a demo and he was using some generic copper cable and we talked about it for some time and he was quite clear, to just use good copper wiring, no need for boutique and all will be well. I believe him to this day.

[RightinLA]

Dec 26, 2012 18:45:44 GMT -5 audiosyndrome said:

Dec 22, 2012 21:03:29 GMT -5 oppman99 said:

Yes,I do understand how to biwire. It makes no difference from a circuit standpoint whether you run two sets of wires to separate binding posts or a single set with a jumper between the posts.

It looks like you don't understand physics (which I have a degree in). Conservation of current is the principle. The sum of current into any junction has to equal the current leaving. All you are doing with biwire is changing the physical location of the junction. There is nothing to separate the frequencies until the current reaches the crossover. Both pairs will carry a full range signal.

My gauge argument still stands. By running the extra wire, you are effectively decreasing the gauge of your run compared to a single set.

Well I don't have a degree in Physics, just bachelors and masters degrees in electrical engineering. To clarify what I've posted earlier, I'll use a slightly different approach.

From Physics, an electrical current flowing in a conductor produces a magnetic field (the FBI rule where F is force, B is magnetic field strength in Gauss, and I is current). Therefore, the current flowing in our speaker cables produces a magnetic field.

This magnetic field varies in accordance with the signal being delivered to the speakers. In particular, the magnetic field of the slightly stronger bass frequencies interacts with the magnetic field of the slightly weaker high frequencies (known as intermodulation distortion IM). Bi-wiring can eliminate this distortion.

How you might ask? By physically separating the magnetic fields of the high and low frequency current. This separation is done in two steps.

1- removing the links between the two pairs of speaker binding posts, thereby totally separating the mid/woofer crossover from the tweeter crossover. Since I=E/R, or more correctly E/Z, and since Z is different for each leg of the crossover, a different current flows in each speaker cable.

2- running two sets of speaker cables to the (now separated) binding posts. The two sets of cables should be separated by an inch or two minimum.

Step 1 directs the low frequencies to the mid/woofer crossover and directs the high frequencies to the tweeter crossover (electrical separation).

Step 2 prevents the magnetic fields from modulating each other as they are physically separated.

Note that Step 2 is just as important as Step 1. If the cables are not physically separated bi-wiring will not work. Two cables in one bundle will not work.

Bi-wiring has nothing to do with skin effect, wire gauge, current in/ current out, etc., only IM distortion due to the magnetic field effect.

I rest my case.

Russ

The magnetic field effects are largely negated in a two wire speaker cable, whereby the current flows in one direction in one wire as it flows in the opposite direction in the other wire. This cancels almost all of the magnet field.

The residual magnetic field would be negligible in most circumstances, would it not? Twisting the wire pair further improves this cancelation and noise rejection as Alexander Graham Bell discovered well over a hundred years ago.

Dec 26, 2012 20:00:08 GMT -5 thepcguy said:

www.sonicdesign.se/biwire.html

THE DISADVANTAGE WITH BI-WIRE

One thing that happens when you biwire your loudspeakers is that the input of the high- and the low-pass filters are fed with different input signals. The difference is a result of the high frequencies and the low frequencies being forced to travel different paths, perhaps through different types of cables, but under all circumstances through cables who have seen different loads (a tweeter with a high pass filter has a completely different impedance response compared to a woofer with a low pass filter!).

What happens is that the drivers will work less good together than when their filter halves were fed with equal signals. The result is a generation of more static and stochastic phase error sounds at different directions from the loudspeaker. The stochastic phase error sounds appear because there may be different types of unlinearities in the low- and high-frequency paths.

What does this sound like? Well, usually, just as you may expect from physics, it appears as a change in the reproduction of space and sound stage. Often, the first impression is that the "biwired" sound presents extended "dimensions", more "air", and is more "living". The impression after a week or month, however, is that all recordings sound very much alike, and the "airiness" appears on all records. It does not even sound like air anymore, instead more like a slime that pollutes every record you play. No wonder, since it is not a real, recorded quality but a "speaker characteristic" added to all reproduced material. "Sameness" is another word for it.



Picture 4: This simulation is based on the diagram of picture 3. Here you can see that a phase difference has arisen when biwiring is used. The reason why the phase difference is largest just above the cross over frequency is that the inductance of the cable resonates with the capacitance of the high pass filter when not the inductance of the low pass filter is available in this range as when single wire is used. The most probable reason to the capricious sound of biwiring is that on top of this steady state error another, transient induced phase error between the cables will appear when playing music. This changes the radiation pattern of the speaker with the music. The human ear is very sensitive to such phenomena.

This is a simulation based on a constructed model. This really needs to be backed up by laboratory measurements to verify model accuracy.

[mgbpuff]

Dec 26, 2012 20:00:08 GMT -5 thepcguy said:

www.sonicdesign.se/biwire.html

THE DISADVANTAGE WITH BI-WIRE

One thing that happens when you biwire your loudspeakers is that the input of the high- and the low-pass filters are fed with different input signals. The difference is a result of the high frequencies and the low frequencies being forced to travel different paths, perhaps through different types of cables, but under all circumstances through cables who have seen different loads (a tweeter with a high pass filter has a completely different impedance response compared to a woofer with a low pass filter!).

What happens is that the drivers will work less good together than when their filter halves were fed with equal signals. The result is a generation of more static and stochastic phase error sounds at different directions from the loudspeaker. The stochastic phase error sounds appear because there may be different types of unlinearities in the low- and high-frequency paths.

What does this sound like? Well, usually, just as you may expect from physics, it appears as a change in the reproduction of space and sound stage. Often, the first impression is that the "biwired" sound presents extended "dimensions", more "air", and is more "living". The impression after a week or month, however, is that all recordings sound very much alike, and the "airiness" appears on all records. It does not even sound like air anymore, instead more like a slime that pollutes every record you play. No wonder, since it is not a real, recorded quality but a "speaker characteristic" added to all reproduced material. "Sameness" is another word for it.



Picture 4: This simulation is based on the diagram of picture 3. Here you can see that a phase difference has arisen when biwiring is used. The reason why the phase difference is largest just above the cross over frequency is that the inductance of the cable resonates with the capacitance of the high pass filter when not the inductance of the low pass filter is available in this range as when single wire is used. The most probable reason to the capricious sound of biwiring is that on top of this steady state error another, transient induced phase error between the cables will appear when playing music. This changes the radiation pattern of the speaker with the music. The human ear is very sensitive to such phenomena.

This article strike me as psuedo scientific. The bi-wire cables are of no consequence in preventing physical intermodulation between tweeter and woofer transducers because the cable is insignificant. But bi-wire keeps the inductive part of the low frequency circuit from actiing on the high frequencies? How is that if the wire impedance is insignificant?

[mgbpuff]

"The magnetic field effects are largely negated in a two wire speaker cable, whereby the current flows in one direction in one wire as it flows in the opposite direction in the other wire. This cancels almost all of the magnet field. "

That's true of the magnetic field external to both conductors but the magnetic field between the two conductors is intensified, thus causing even more IM distortion between low and high frequencies flowing in the wires which do not flow in the same concentric portions of the conductor.

[charlie7]

"Bi-wiring has nothing to do with skin effect, wire gauge, current in/ current out, etc., only IM distortion due to the magnetic field effect.

I rest my case.

Russ"

So, if there is a reduction of IM distortion through bi-wiring, would it not be possible to measure it and have empirical evidence of this reduction and allow comparison to standard wiring methods?

However, since speakers typically have distortion measured in several percent, (I've seen 10% thrown around as an average) even if there was a measured improvement in the IM distortion via bi-wiring, would it not be so small compared to distortion inherent in any speaker as to be inaudible?

Installing room treatments to reduce comb filtering, early reflections and modes did more to increase the sound quality of my system than any change in equipment. As audiophiles, we often forget the most important component that affects the sound of our systems is the room.

Charlie

[Boomzilla]

Dec 18, 2012 19:23:53 GMT -5 hemster said:

In most cases, Bi-wire = Buy-wire!

ROTFLMAO - That sounds right!

[mgbpuff]

Thanks to those who came at this discussion with logical physics or electrical field theory arguments that may account for differences, although subtle, between bi-wiring and single wiring (mainly RichGuy and Audiosyndrome). I am convinced that there is some science to it now, even though many other type of adjustments to one's audio system may make far greater improvement.

[12elfthfloor]

For every connection such fun awaits!

Attachments:

[mgbpuff]

12elfthfloor - is that tri-wiring or tri-amping o the KEF 207s with your 2 XPA3s? Either way it looks very well done. Congratulations.

Never mind - I see in Reply #8 that you are tri-wiring.

[12elfthfloor]

Thank you. I would love to try my XPA-3s to tri amp but i need some XLR splitters.