Why Bi-wiring Makes No Sense.

[jonnythan]

jneutron, I thin it's time for you to show us some numbers or shut up.

 

[Omicron]

Show that the tweeter filter power has ANYTHING to do with the woofer impedance in a biwire config..

Ok, it doesn't. Are you happy now? I just gave you all the equations that say so in post 431. Or are you just too stupid to understand them?

Unfortunately that issue is totally beside the point as the equations show that the power in the speakers, the ONLY power that matters by the way, is totally unaffected by any of this.

And by all means DO replace the woofer with any combination of inductors, capacitors or resistors your fertile imagination might conjure up. It won't affect the equation for the power in the tweeter (the tweeter, not the filter) one bit for these simple 2 reasons:

1) no circuit element behind the LF filter can affect the HF signal (the impedance of the LF filter is infinite for HF signals)

2) no change to the LF signal, be it in amplitude or phase, can propagate down to the tweeter because the impedance of the HF filter is infinite for the LF signal.

And I DO remind you that the simplification of using ideal filters was yours, not mine.

No matter how much you shout or scream about reactive components, nothing will chance this simple fact.

PS: there is a typo in post 431, the expressions for Pfil-wf and Pfil-tw have been reversed. Not that it matters any.

 

[Omicron]

Show that the tweeter filter power has ANYTHING to do with the woofer impedance in a biwire config..Anything..

And by the way it only depends on what viewpoint you take. If you write the equations in terms of current, then yes the tweeter filter power is depended on the woofer impedance.

If you write them in terms of voltage then it isn't.

Two sides of the same coin. Depends on if you model the amp as a current source or as a voltage source. The equations are equivalent, except in the extreme cases:

- the current based equations blow up if you remove one of the current paths

- the voltage based equations blow up if you short circuit on of the voltage loops

I did you the courtesy of re-writing my equations so they match with your voltage source interpretation of the amp.

All elementary stuff. Why do I even have to explain all this?

 

[Audioholics]

This is what you guys look like to the rest of us:

 

[Seth=L]

Big bold letters mean there must be some sense of urgency, has bi-wiring become that important?

 

[Omicron]

This is what you guys look like to the rest of us:

You are right. I apologize to the readers of the forum for dragging out this discussion as long as I have.

I would like to close my involvement in this issue with a question to the patient readers of this thread: as we all know the audio field is filled with dubious claims that are often used to justify equipment costing unbelievable amounts of money (not claiming jneutron has any commercial motives, but his claims could easily be abused by persons who do). For someone who (thinks he is) in a position to provide a counter-argument to one such claim, what do you feel the correct response should be: do nothing and walk away shaking ones head hoping not to give the claimant more attention then he or she deserves? Or engage in the discussion and try to expose the bogus claim, but risk getting bogged down in threads like this? Personally I haven't yet found a satisfying answer to this question and occasionally allow myself to get dragged into conversations like these.

I do hope some of my posts were of some use to at least someone somewhere out there

 

[haraldo]

You are right. I apologize to the readers of the forum for dragging out this discussion as long as I have.

I'm sure Seagate is happy about this discussion because now Gene has to buy more disks

 

[jneutron]

It's fun to watch engineers do battle. They spill numbers, not blood.

You have not been watching two engineers do battle. You have been watching one engineer. The other "party" (me) has used all the "yaysayer" tricks and methods he can think of to trip the engineer up....

Two engineers talking about this would be like watching grass grow.

But I fear I've run out of yaysayer tricks. The jig is up.. I'm gonna leave this devils advocate cr## to someone younger that I.

Big bold letters mean there must be some sense of urgency, has bi-wiring become that important?

It's supposed to emphasize how correct I am..and how wrong everybody else is..oh, don't forget color...very important as well. Combining both with bold and italics really means business.

You are right. I apologize to the readers of the forum for dragging out this discussion as long as I have.

Don't be. I'm sure many people got a good taste of what actual engineering is all about. You've been a fun "opponent".

as we all know the audio field is filled with dubious claims that are often used to justify equipment costing unbelievable amounts of money (not claiming jneutron has any commercial motives, but his claims could easily be abused by persons who do). For someone who (thinks he is) in a position to provide a counter-argument to one such claim, what do you feel the correct response should be: do nothing and walk away shaking ones head hoping not to give the claimant more attention then he or she deserves? Or engage in the discussion and try to expose the bogus claim, but risk getting bogged down in threads like this? Personally I haven't yet found a satisfying answer to this question and occasionally allow myself to get dragged into conversations like these.

It depends on the thread I guess.

Oh, and I don't have any commercial motives. But I have seen many biwiring claims in the past by manufacturers..

I do hope some of my posts were of some use to at least someone somewhere out there

I'm sure they were useful to many..In fact, this brainstorming session (or silly diatribe) helped me figure out where my positive result may have come from..

I'm sure Seagate is happy about this discussion because now Gene has to buy more disks

I think Gene has fallen behind in that regard. It seems that stored in my attachment folder is about a meg and a half more of files than we are allowed. I'm faced with having to delete many of my attachments in order to post any new pictures or schematics..


I figured the jig was up at post 358..when I told EJ1....

Keep in mind, however. What Kurt is saying is consistent with all the electrical engineering we have all learned over the years..

What I am providing in terms of analysis, seems to fly in the face of all that we were taught..

His way, until proven otherwise, is the correct one...linearity of circuits has been gospel now for a century or so, and serves us well.

My position cannot be adopted unless many others have duplicated my test results..
After all, engineering is not anarchy.....

As that was so inconsistent with my presentation...

As to my positive test results...The circuit I put together is extremely sensitive to any differences that occur, I was left with an inconsistency, one which differentiated between the mono and biwire configuration..

My suspicion is that the tweeter capacitors are acting in a non linear fashion, and the "relatively speaking" DC voltage of the lf signal is forcing the dielectric to behave differently.. I've never seen much real data on crossover cap capacitance vs dc voltage. The test instrumentation I used on the caps gives me values from 20 hz to 1 Mhz, but the bias I can put on the cap is rather limited, 2 to 4 volts dc is the max..

I also cannot rule out the inductors, but air core solonoids are generally well behaved linear devices. As long as you maintain packing density and form factor, you generally get no suprises.

That was why I asked you if you were in a position to duplicate the test..

Cheers, John

 

[jneutron]

test test.

my goodness...I deleted quite a few jpgs from my attachment folder, and I still get "exceeds" size by 650 kb...What's going on?

I don't have the heart to delete all the t-line graphs, the LC energy plots, the inductance calculation graphs..or the wire guage plots...

Are we really limited to 500k per registered user?

Now I'm sorry I deleted all the pictures showing the issues involved with the house neutral integrity...I can't put them back now, so the links are broken..

Oh well..



Cheers, John

 

[gmichael]

I'll do better than tat. I'll give you a generic solution for either schematic. With the equations I'm going to derive for you, you can calculate all powers in either circuit. So we will hopefully end this sillyness once and for all. And if you object then show us YOUR equations and stop blabbering!

Let us suppose a circuit "halfway in between" the mono and bi-wire cases. One set of wires leaving the amp. Halfway they split into 2 sets of wires one going to the tweeter, one to the woofer. Say:

Rw1 = wires from the amp to the "in between" node
Rw2 = wires from "in between" node to the tweeter
Rw3 = wires from "in between" node to the woofer

The bi-wired case can then be considered as Rw1 = 0 and conversely the mono wire case can be considered Rw2 and Rw3 = 0. So the resulting set of equations will apply to both. We will also consider voltage drive and all expressions will be done in terms of voltage only (just so you can remove the woofer branch without breaking the equations on an infinity).

So:

Pamp = Pw1 + Pw2 + Pw3 + Pfil-tw + Pfil-wf + Ptw + Pwf

With:

Pamp: power put out by the amp
Pw1, Pw2, Pw3: the wire losses
Pfil-tw: power term of the tweeter filter
Pfil-wf: power term of the woofer filter
Ptw: power term of the tweeter
Pwf: power term of the woofer

Al being functions of time (not talking about average power here).

From this we can say:

Pspeakers = Ptw + Pwf = Pamp - (Pw1 + Pw2 + Pw3 + Pfil-tw + Pfil-wf)

What we want to prove here is that there is no distortion in the speakers and hence the power in the speakers must be given by an expression that looks like this:

Pspeakers = K1*sqr(Va) + K2*sqr(Vb)

With K1 and K2 constants that must be independent of time and independent of either Va or Vb. Va is the HF signal and Vb is the LF signal. Both functions of time (although their exact shape doesn't matter, only that one is pure LF and the other pure HF).

Good, let's start:

Pamp = (Va + Vb)*(Ia + Ib)

Using the fact that the filters have either zero or infinite impendance for each signal, we can calculate the resistance seen by the LF and HF signals:

Let us call:

Ra = Rw1 + Rw2 + Rtw -> HF resistance
Rb = Rw1 + Rw3 + Rwf -> LF resistance

Then

Ia = Va / Ra -> HF current
Ib = Vb / Rb -> LF current

Or:

Pamp = (Va + Vb) * ( Va / Ra + Vb / Rb )
Pamp = sqr(Va) / Ra + sqr(Vb) / Rb + Va*Vb*(1/Ra + 1/Rb)

Pamp = sqr(Va) / Ra + sqr(Vb) / Rb + Va*Vb*(Ra+Rb)/(Ra*Rb) [equation 1]

Next, the power in the wires:

Pw1 = Rw1 * sqr(Iw1) = Rw1 * sqr(Ia + Ib) = Rw1 * sqr(Va / Ra + Vb / Rb)
Pw1 = Rw1 * sqr(Va/Ra) + Rw1 * sqr(Vb/Rb) + 2*Rw1*Va*Vb/(Ra*Rb) [equation 2]

The power in the other wires is trivial and:

Pw2 = Rw2 * sqr(Ia) = Rw2 * sqr(Va/Ra) [equation 3]
Pw3 = Rw3 * sqr(Ib) = Rw3 * sqr(Vb/Rb) [equation 4]

The power in the filters can be found:

Pfil-tw = Vfil-tw * Ifil-tw

Since the HF filter cannot drop an HF voltage (it's impedance is 0) it must drop all of the LF voltage (b) remaining at the end of the wires:

Vfil-tw = Vb - Vbw1 - Vbw2 - Vbtw

Note that since the HF filter cannot pass the LF current, wire 2 cannot be carrying any LF current so cannot drop any LF voltage either. Same for the tweeter. Hence Vbw2 = 0 and Vbtw = 0.

Vfil-tw = Vb - Ib*Rw1 - 0 - 0
Vfil-tw = Vb - Ib*Rw1
Vfil-tw = Vb - (Vb/Rb)*Rw1
Vfil-tw = Vb*(1 - Rw1/Rb)

Since the filter cannot pass an LF current:

Ifil-tw = Ia = Va / Ra

So:

Pfil-tw = (Va/Ra)*Vb*(1 - Rw1)/Rb)
Pfil-tw = Va*Vb*(Ra - Rw1)/(Ra*Rb) [equation 5]

In the same way we can calculate the power term for the woofer filter:

Pfil-wf = Va*Vb*(Rb - Rw1)/(Ra*Rb) [equation 6]


We are now in a position to calculate:

Pspeakers = Ptw + Pwf = Pamp - (Pw1 + Pw2 + Pw3 + Pfil-tw + Pfil-wf)

By combining equations 1, 2, 3, 4, 5 and 6 :

We will do this in 3 steps:

1) gather all the terms of sqr(Va):

k1 = 1/Ra - (Rw1 + Rw2)/sqr(Ra)

2) gather all the terms in sqr(Vb):

k2 = 1/Rb - (Rw1 + Rw3)/sqr(Rb)

3) gather all the terms in Va*Vb:

k3 = (Ra+Rb)/(Ra*Rb) - 2*Rw1/(Ra*Rb) - (Ra - Rw1)/(Ra*Rb) - (Rb - Rw1)/(Ra*Rb)

k3 = (Ra + Rb - 2*Rw1 - Ra + Rw1 - Rb + Rw1)/(Ra*Rb)

k3 = 0 / (Ra*Rb)

k3 = 0

This gives us the expression for the power in the speakers:

Pspeakers = Ptw + Pwf = k1*sqr(Va) + k2*sqr(Vb)

As we can see, since k3 always works out to 0 and neither k1 nor k2 contain any dependencies on Va or Vb, the dissipation in the speakers is just a linear combination of the powers we would expect for an undistorted case.

Let's see what k1 and k2 work out to for the mono and bi-wire cases:

For mono:

Rw = Rw1
Rw2 = Rw3 = 0 so
Ra = Rw1 + Rw2 + Rtw = Rw + Rtw
Rb = Rw1 + Rw3 + Rwf = Rw + Rwf

k1 = 1/(Rw + Rtw) - Rw/sqr(Rw + Rtw)
k2 = 1/(Rw + Rwf) - Rw/sqr(Rw + Rwf)

For the bi-wire case:

Rw1 = 0
Rw2 = Rw3 = Rw so
Ra = Rw1 + Rw2 + Rtw = Rw + Rtw
Rb = Rw1 + Rw3 + Rwf = Rw + Rwf

k1 = 1/(Rw + Rtw) - Rw/sqr(Rw + Rtw)
k2 = 1/(Rw + Rwf) - Rw/sqr(Rw + Rwf)

Surprise surprise...since k1 and k2 are the same the power in the speakers is also exactly the same in both cases! Not even a difference in magnitude. If you use the same wire resistances, obviously. Otherwise there will be a difference in magnitude, but in magnitude ONLY! Nothing that cannot be fixed by turning the amp up a tad.

Note: As a simple sanity check we will put some numbers in our equations as see if they hold up:

Let's say:

Rw1 = 2 ohms
Rw2 = 4 ohms
Rw3 = 8 ohms
Rtw = 12 ohms
Rwf = 16 ohms
Va = 3 V (instanteneous value, not RMS or average or peak)
Vb = 5 V (instanteneous value, not RMS or average or peak)

Then:

Ra = 2 + 4 + 12 = 18 ohms
Rb = 2 + 8 + 16 = 26 ohms

k1 = 1/18 - (2 + 4)/sqr(18) = 0.037037
k2 = 1/26 - (2 + 8)/sqr(26) = 0.023669

Pamp = sqr(3) / 18 + sqr(5) / 26 + 3*5*(18+26)/(18*26) = 2.871 W
Pw1 = 2 * sqr(3) / sqr(18) + 2 * sqr(5) / sqr(26) + 2*2*3*5/(18*26) = 0.257 W
Pw2 = 4 * sqr(3/18) = 0.111 W
Pw3 = 8 * sqr(5/26) = 0.296 W
Pfil-tw = 3*5*(18 - 2)/(18*26) = 0.513 W
Pfil-wf = 3*5*(26 - 2)/(18*26) = 0.769 W
Pspeakers = 0.037037*sqr(3) + 0.023669*sqr(5) = 0.925 W

And indeed:

2.871 = 0.257 + 0.111 + 0.296 + 0.513 + 0.769 + 0.925

Uhm.....

I may speak for a few members here when I say, "Huh?"

 

[trnqk7]

Try following it through-it's tedious, but I find it makes sense. The notation of sqr is confusing-he should have used x^2 instead of sqr(x)...sqr generally meants square root to most people, not squared. That may ease some confusion.

 

[mouettus]

Try following it through-it's tedious, but I find it makes sense. The notation of sqr is confusing-he should have used x^2 instead of sqr(x)...sqr generally meants square root to most people, not squared. That may ease some confusion.

Still... lol

 

[Halon451]

Uhm.....

I may speak for a few members here when I say, "Huh?"

The answer is "42".

And the wheels on the bus go 'round and 'round... 'round and 'round...

 

[haraldo]

The answer is "42".

And the wheels on the bus go 'round and 'round... 'round and 'round...

I always known that the answer is 42, what's the question

Yeah, meaning of life..... The answer is 42 !

Ever wondered about perpetual mobile......
Found it Jneutron and Omicron. They will go on forever, jesus no criticism though
Where do they get the energy !!!!!

 

[Highlander]

This is what you guys look like to the rest of us...

Never a truer word spoken.

Two engineers talking about this would be like watching grass grow.

Oh, the irony.

 

[haraldo]

Never a truer word spoken.



Oh, the irony.

I guess I'd rather see paint drying up, that's much more fun

 

[audiotraine]

You gotta admit biwiring looks freakin' cool!

im headed that way dude!@##$%%^&&* you said "freakin cool" U B T MaN

who said -protons-neutrons--electrons--morons :and all us other unbelievers
it is in its infancy---alchemist--right?!?! ie:strands of small wire--different morons and such attractants &&& "did i say that" i meant one of them other --rons- words dam the torpedoes--full speed, i mean- half volumes ahead -- xcuse my french@#$! -besides--- resistances causes fluctuations $ distortions in frequency responses---ie--noise bad--music good--mo power better-- less db loss at any volume-ie-"mo amps"-whether audible or not -another discussion--tons of head room-to shove that water down dem freakin cool wires with no fluctuations==or somepin lik dat?!?!??!!?!?

 

[audiotraine]

Huh

Uhm.....

I may speak for a few members here when I say, "Huh?"

Me too too ?Huh?

 

[haraldo]

im headed that way dude!@##$%%^&&* you said "freakin cool" U B T MaN

who said -protons-neutrons--electrons--morons :and all us other unbelievers
it is in its infancy---alchemist--right?!?! ie:strands of small wire--different morons and such attractants &&& "did i say that" i meant one of them other --rons- words dam the torpedoes--full speed, i mean- half volumes ahead -- xcuse my french@#$! -besides--- resistances causes fluctuations $ distortions in frequency responses---ie--noise bad--music good--mo power better-- less db loss at any volume-ie-"mo amps"-whether audible or not -another discussion--tons of head room-to shove that water down dem freakin cool wires with no fluctuations==or somepin lik dat?!?!??!!?!?

Happy to give you your first thanks for this very useful post

 

[BudgetHT]

I didn't have time to read this whole thread and maybe this has already been stated, but I think everyone has missed the point of Roberts book... You bought it, he made money. His approach worked.