bi-wire theory

[justw]

W, what do you mean by tri-wired?? Your large Advents are a two way system .... right??


Where is the 3rd set of wires going??


Regards,
Jerry

The third pair of Advents. I have three pairs stacked.

 

[Cloth Ears]

Bi-amping uses a line level crossover to feed individual amps for low and high ends, or in the case of tri-amping low/mid/high signals.

Line level crossovers is actively crossing, no bi-amping. Bi-amping, as currently used terminology, is using the passive crossoveers in your speakers, but using a separate amplifier to drive them. So you actually have a full-range signal from each amplifier feeding into the passive crossover on your speakers. If you used a line level crossover and then fed this signal into your speakers, you would find weird things happening at the crossover point. If you actively cross, then you should not have a passive crossover as well.

Bi-wiring removes the physical connection between the woofer/tweeter at the speaker and replaces it with 2 sets of wires that connect at the amp ouput..

Noting, of course, that you can only do this with parallel crossovers. It doesn't work with series crossovers.

As to the original question, I have no idea how this would make most speakers sound different or better since the only difference (as far as I can see) is the length of wire connecting the low and high sections of a passive speaker crossover.

I may have misunderstood what he meant by 'strap', but all my bi-wireable speakers' manuals SCREAMED to remove the connecting strap (that ran between the 4 posts on back of speakers) before using biwire.

For my Elac speakers, bi-wiring is an improvement, but only because the 'straps' are so crappy. I could just use a 3-inch piece of speaker wire between the lugs on the speakers... but when you've got enough cable you can impress your male friends with all the wires.:scratch2:

 

[cableguy2]

Well, I guess my first question is how MUCH EMF is being produced to affect the high end. Hell, for all I know, my whole house may be emitting more EMF than what goes into the speaker cabs. So does that mean I should make sure my cabinets have a good lead foil lining?

Sometimes I think we want to believe something so much that we will talk ourselves into noticing a difference. Maybe some people can, but I have been deaf in one ear and have loss in the other most of my life. My speakers just need to be DAMM LOUD. That way, I can hear most everything.

 

[Lefty]

Well, I guess my first question is how MUCH EMF is being produced to affect the high end. Hell, for all I know, my whole house may be emitting more EMF than what goes into the speaker cabs. So does that mean I should make sure my cabinets have a good lead foil lining?

Sometimes I think we want to believe something so much that we will talk ourselves into noticing a difference. Maybe some people can, but I have been deaf in one ear and have loss in the other most of my life. My speakers just need to be DAMM LOUD. That way, I can hear most everything.

Well how much back EMF and it's effect is a valid question. However it sounds like you are mistaking back EMF (electromagnetic force) with EMI (electromagnetic interference). These are separate and unrelated items.

Lefty

 

[Raphael]

Mmmmmmm . . . lead foil lining . . . sounds edible.

 

[Cloth Ears]

The gist of it is to separate the x-over into it's hi and lo components--essentially making a parallel x-over that's bi-wirable. This--of course--would be different for many x-over designs and requires new component values so should only be accomplished by those who feel comfortable with x-over modifications and knows or can accurately extrapulate his/her x-over points based on speaker/cabinet design. Basically . . I know enough not to try it!

But doesn't that spoil the point of the series cross-over in the first place? The whole idea of series is that each part of the x-over affects the other - if the voice coil of one speaker heats up then the increased resistance means that the other speaker takes up a bit more of the load. In a parallel cross-over this is not the case, so the voice coil of one speaker heating up causes the dynamics of the cross-over to change.

 

[gadget73]

I guess this is sort of on topic here, but would it be possible to modify a set of 2-way speakers to accept a bi-wire arrangement? I have an old tube bi-amp, and the speaker setup I have is not currently in any sort of a cabinet. I was thinking about modding my cheap Insignias so that the tweeter and woofer are driven independant of one another so that I can hook it up to my tube bi amp. Would this simply be a matter of disconnecting the crossover for the tweeter (probably just a simple cap, I don't expect anything fancy for $50) and connecting the leads for the tweeter directly to a second set of banana jacks on the back?

 

[justw]

Well, I guess my first question is how MUCH EMF is being produced to affect the high end. Hell, for all I know, my whole house may be emitting more EMF than what goes into the speaker cabs. So does that mean I should make sure my cabinets have a good lead foil lining?

Sometimes I think we want to believe something so much that we will talk ourselves into noticing a difference. Maybe some people can, but I have been deaf in one ear and have loss in the other most of my life. My speakers just need to be DAMM LOUD. That way, I can hear most everything.

Well, put a voltmeter across your speaker leads, disconnected from your amp, and push on the woofer cone. You may be surprised with the result.

 

[Nakdoc]

Am I too late to the party?
Forget the "back emf " stuff. Conceptually it is on the right track, but it misses the thing that bi-wiring does. Amplifier "DF Damping Factor" is the ratio of the amplifier's output impedance to the load impedance. Both impedances are complex, meaning they have resistive, capacitive, and inductive elements.This also means that both change with frequency. Low damping factor, found in typical transformer coupled amps and units with lousy speaker switches, relays and fuses, is DF=10. Good mid fi solid state amps have DF=100, and there are no doubt audiophile amps with DF=250 or better. DF in practical terms is a measurement of an amplifier's ability to stop and start the dynamic mass of the transducer. High DF might be called "tighter" or "controlled". Low DF might be called "wooly" or "fat". DF is also what gobbles up the back EMF, and makes it go away (it is the load for back EMF).
What bi-wiring does is separate the tweeter's damping factor as much as possible (to the user anyway) from the woofer's. Speaker wire reduces DF. Some speaker wires reduce DF a lot! The "tighter control" of the tweeter images more precisely.
I was a non-believer until hearing a set of Apogee Duetta ribbon speakers in bi-wire and conventional. We listened to a Sting CD with him noodling along vocally with a percussion style electronic sound behind him. When we switched to bi-wire, that percussion sound swept for side to side in the best Led Zepplin fashion. Wires back to normal, and the movement was gone. Apogees have very little back EMF;they are very low impedance and almost purely resistive in load. A hi end amp with DF=200 drops to less than 80 on Apogees. I will suggest that bi wiring audibility depends on the change effected in DF, but I haven't verified this. If your system has low DF, bi-wiring will have little audible effect. DF is found in some spec sheets. Audio magazine used to test for it in the old days.

 

[tcdriver]

Would this simply be a matter of disconnecting the crossover for the tweeter (probably just a simple cap, I don't expect anything fancy for $50) and connecting the leads for the tweeter directly to a second set of banana jacks on the back?

Yes, however, if there is a crossover component connedted to the tweeter, leave it in place. i.e. If there is a series capacitor make sure it is still in series with the tweeter.

 

[Raphael]

But doesn't that spoil the point of the series cross-over in the first place? The whole idea of series is that each part of the x-over affects the other - if the voice coil of one speaker heats up then the increased resistance means that the other speaker takes up a bit more of the load. In a parallel cross-over this is not the case, so the voice coil of one speaker heating up causes the dynamics of the cross-over to change.

Yes it does "spoil the point" but isn't that what you are trying to do? Get away from the dependence the drivers have on each other in formulating the spectrum of sounds and allow them to independently focus on the ranges they were designed for given a well engineered crossover point (no freq gap or overlapping and filtered to within the easy driving range of each driver).

From previous reading--which I am only now remembering--Nakdoc hits the nail on the head regarding the benefits of Bi-wiring--namely higher DF resulting in faster/cleaner sound (however significant or slight).

 

[BobK101]

Hi,
I have Vandersteen II 's and they recomend Bi Wiring... Here is a very interesting article on it from their web site... Worth a read..

http://vandersteen.com/pages/Answr7.htm

Bob

 

[bjarmson]

I've been bi-wiring my Platinum Audio PT-808s since I got them, because when I was using Platinum Audio PT-801s and changed to bi-wiring they seemed to have a bit clearer sound. Since each wiring post on my Kenwood 600 and 9100 amps have two sides to insert wires, I simply insert a wire on both sides, no need to twist wires together.
One thing I'd recommend is marking the wires left/right so you don't get them confused (easy to do with four wires running from your amp). Oh, and don't forget to remove the woofer/tweeter connectors from your speakers before bi-wiring.

 

[whoaru99]

A lot of people hear what they want/expect to hear and it's real easy to claim one hears a change when one knows a change has been made.

After all, who can prove you don't hear a difference?

 

[Lefty]

A lot of people hear what they want/expect to hear and it's real easy to claim one hears a change when one knows a change has been made.

After all, who can prove you don't hear a difference?

And that's why things electronic should be judged using the scientific method with reproducible evidence and peer review. It's gotten us this far in technology and I see no reason to abandon it now for new wave, feel good, sound good, subjective opinions and theories.

The problem with Hi-Fi is it is where art meets technology. The art (music) rightfully brings out emotions, love and pleasure in us, but the tendency is strong to wrongly attribute these attributes to the electronics rather then the artist's creation. Electronics gets far too much blame and credit for how our favorite music makes us feel...

Lefty

 

[ultralc]

I am guessing that most people with bi-wiring "theories" never went to science class in high school and certainly not an EE in college.

Take EMF for example. Woofer EMF is produced by cone movement, and cone movement is driven by the voltage/current from the amp. Normal EMF is the the same frequency as the source and in opposite polarity. As such, it should reduce the low frequency presence on the HF cross-over, and should be beneficial based on the EMF "theory". In other words, the EMF theory is totally backwards. For the EMF from un-controlled woofer resonance, the frequency is way below cross-over point, it is insignificent in magnitude after cross-over and your mid-range and tweeter can't produce this low frequency anyway. And do remember, low frequency signals from the amp, including signals below and above woofer resonance, which is much higher than EMF, are still present on the HF cross-over network, regardless how you wire it.

Now look at the resistance and damping factor. Let's say you originally only have one set of wires, now you add an identical set, one for LF and the other for HF, separately. Guess what, the LF singals still travel down the same wire with the same resistance so they have the same loss and the same dapming factor. And it is exactly the same senario for HF singals. It is only beneficial if you also connect these two sets of wires at the speaker end, effetively cutting wire resistance by half, so that it might be significant in some applications depending on the wire size and speaker impedance.

 

[onplane]

And that's why things electronic should be judged using the scientific method with reproducible evidence and peer review. It's gotten us this far in technology and I see no reason to abandon it now for new wave, feel good, sound good, subjective opinions and theories.

Lefty

Lefty, your point is a good one. Further, it would be very easy to bi-wire a single speaker and compare to the other using a mono source and either the balance control or speaker A/B.

In addition, once setup, you could ask others whether they can hear any difference WITHOUT sharing which speaker is bi-wired.


Regards,
Jerry

 

[jstang]

I just saw this thread .....a month late. But I am a beleiver in Bi-wiring.....:yes:

http://audiokarma.org/forums/showthread.php?t=105980

jk

 

[wineslob]

Am I too late to the party?
Forget the "back emf " stuff. Conceptually it is on the right track, but it misses the thing that bi-wiring does. Amplifier "DF Damping Factor" is the ratio of the amplifier's output impedance to the load impedance. Both impedances are complex, meaning they have resistive, capacitive, and inductive elements.This also means that both change with frequency. Low damping factor, found in typical transformer coupled amps and units with lousy speaker switches, relays and fuses, is DF=10. Good mid fi solid state amps have DF=100, and there are no doubt audiophile amps with DF=250 or better. DF in practical terms is a measurement of an amplifier's ability to stop and start the dynamic mass of the transducer. High DF might be called "tighter" or "controlled". Low DF might be called "wooly" or "fat". DF is also what gobbles up the back EMF, and makes it go away (it is the load for back EMF).
What bi-wiring does is separate the tweeter's damping factor as much as possible (to the user anyway) from the woofer's. Speaker wire reduces DF. Some speaker wires reduce DF a lot! The "tighter control" of the tweeter images more precisely.
I was a non-believer until hearing a set of Apogee Duetta ribbon speakers in bi-wire and conventional. We listened to a Sting CD with him noodling along vocally with a percussion style electronic sound behind him. When we switched to bi-wire, that percussion sound swept for side to side in the best Led Zepplin fashion. Wires back to normal, and the movement was gone. Apogees have very little back EMF;they are very low impedance and almost purely resistive in load. A hi end amp with DF=200 drops to less than 80 on Apogees. I will suggest that bi wiring audibility depends on the change effected in DF, but I haven't verified this. If your system has low DF, bi-wiring will have little audible effect. DF is found in some spec sheets. Audio magazine used to test for it in the old days.

Nakdoc, excellent explaination and a perfect discription of what I hear in my system.
What did you think of the Ap's?

 

[stuartk]

oops