The Heresy of the T/S Parameter Bl

[smowry]

Your own derivation actually confirms the point: beta is not an independent physical quantity.
It is algebraically derived from magnetic flux density B and from the geometry and material of the voice coil.
Those same quantities also define Bl.
The fact that beta can be obtained directly from FEM does not make Bl misleading or obsolet, it simply means that both parameters originate from the same underlying motor physics.
FEM can just as well be used to compute Bl from the same field solution.
Physically, the dominant term in both expressions remains B, the flux density in the gap.
Beta is therefore not a new degree of freedom, but a different representation of the same motor properties, with resistance and conductor volume folded in.
Sensitivity (SPL/1 W) is not determined by beta alone, but by the full set of parameters (Bl, Mms, Re, Sd, etc.).
Beta = convenient composite metric.
Bl = fundamental motor constant.
One does not invalidate the other.
So the issue is not scientific correctness, but interpretation and emphasis:
Bl is necessary but not sufficient.
Beta is a derived metric.
The disagreement is about representation, not physics.
Finally, repeatedly framing this as “heresy” is inappropriate in a scientific and engineering forum.
“Heresy” is a religious term, historically used by inquisitors to condemn dissent, not to resolve technical questions.
In science, disagreements are not settled by theological rhetoric.

Qes is a derive metric.

SPL is a derived metric.

Only B is a fundamental quantity.

Both Bl and Beta are derived from B.

Heresy is used in this discussion as a metaphor to indicate false teachings in hopes of drawing attention to an important matter. This is a common technique for authors. It is not used as a proof of anything. All claims are quantified and no claim is proven by metaphor.

Why is Beta ignored in Date Sheets by all transducer manufacturers except Peerless?

 

[smowry]

Note that I will answer any serious technical question if I can; however, only @Lars Risbo and @NTK take time to answer my questions. Is one that ignores questions ignorant, maybe? On the other hand, ignoring direct questions does not indicate knowledge of the matter under discussion. It may imply otherwise.

 

[Snickers-is]

Qes is a derive metric.

SPL is a derived metric.

Only B is a fundamental quantity.

Both Bl and Beta are derived from B.

Sure, but you have yet to demonstrate a method to determine it precisely under load without going via Bl. That means while Bl is determined by an integral of B and l, it translates to the primary parameter that we actually determine B and beta from.

Heresy is used in this discussion as a metaphor to indicate false teachings in hopes of drawing attention to an important matter. This is a common technique for authors. It is not used as a proof of anything. All claims are quantified and no claim is proven by metaphor.

You need to have a valid case to begin with. Without a valid case, it just ends up as an attempt to bypass the discussion.

Why is Beta ignored by all transducer manufacturers except Peerless?

The answer to that question has been very thoroughly given at this point.

To put it very briefly:
1: The way they determine Bl makes it one of the primary measured parameters.
2: Their customers mostly don't need beta, and the few that do can easily calculate it for themselves. They do, however, need Bl all the time for LEM simulations.
3: Their customers know that Bl is a measure of force as a function of current, and nothing else.

 

[Snickers-is]

No, but this thread is slowly giving me an idea of why it wasn't wrong of me to always view BOSE speakers with a healthy dose of skepticism.
That was also my last post in this thread.
I really don't feel like being insulted.

And maybe you would have designed some brilliant transducers. The question strikes me as an attempt to invalidate your point by making you respond to a point that appears to be valid, but just isn't.

@smowry is constantly referring to @Lars Risbo, a man who, despite being a brilliant driver engineer, jumped fairly quickly from semiconductors to electromechanics. And I think we can all agree that he did so rather successfully. He has, however, not confirmed any of Stephen's claims. But he is referred to as if he has.

 

[smowry]

@NTK

Your work is intriguing and it has stirred a question.

If we look at Dr. Klippel's large signal transducer model below,

why can't you consider power rather than just u(t) or i(t)? Rather than Bl(x)i(t), could you use β(x)u(t)i(t) N^2 or
[β(x)u(t)i(t)]^0.5 N? Ohm's Law tells us u(t) = Z(x)i(t) V. Then Z(x) = u(t)/i(t) Ω.

Your simulation work is really impressive. Your presentation was quantitative and with good documentation and no nonsense. You didn't need to personally attack me to make your point. Why do you behave like that?

 

[KSTR]

Why is Beta ignored in Date Sheets by all transducer manufacturers except Peerless?

Beta is quickly derived from parameters BL and Re which are always stated, so what? It is good engineering practice to remove redundancy. Same goes for efficiency where you additionally need Mms and Sd.

 

[Snickers-is]

why can't you consider power rather than just u(t) or i(t)? Rather than Bl(x)i, could you use β(x)u(t)i(t) N^2 or
[β(x)u(t)i(t)]^0.5 N? Ohm's Law tells us u(t) = Z(x)i(t) V. Then Z(x) = u(t)/i(t) Ω.

Virtually everyone here is trying to explain to you that this is because the impedance is not constant.

 

[Salt]

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[smowry]

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90 posts and only @Lars Risbo, @NTK, and @smowry have made informative posts. Many of the posts have been argumentative or personal attacks. I have reported numerous posts; however, unfortunately corrective action is unavailable.

@NTK posted, "Before this thread get locked (just in case), I'll give an example of time domain simulation." When hecklers join and one tries to defend their claims, the entire group gets denied. @Lars Risbo, @NTK, and @smowry are dedicated to high standards, while several members are committed to compromising the status and stature of the ASR forum. They think it's okay to belittle and insult. I disagree!

 

[Salt]

90 posts and only @Lars Risbo, @NTK, and @smowry have made informative posts. Many of the posts have been argumentative or personal attacks. I have reported numerous posts; however, unfortunately corrective action is unavailable.

@NTK posted, "Before this thread get locked (just in case), I'll give an example of time domain simulation." When hecklers join and one tries to defend their claims, the entire group gets denied. @Lars Risbo, @NTK, and @smowry are dedicated to high standards, while several members are committed to compromising the status and stature of the ASR forum. They think it's okay to belittle and insult. I disagree!

Last time and comment: cool down, this is a forum (literally means 'to all') and not a cathédrale.

 

[RexrothPigeon]

Finally, repeatedly framing this as “heresy” is inappropriate in a scientific and engineering forum.
“Heresy” is a religious term, historically used by inquisitors to condemn dissent, not to resolve technical questions.
In science, disagreements are not settled by theological rhetoric.

hear, hear

 

[Snickers-is]

Skrive

It was @Matias that invited Lars to the Thread and not I.


Note that the ASR user interface is Johnson.

And no one has said anything about it. But you have referred to Lars as having confirmed, or showing agreement in your point of view numerous times. No one has backed your claims at this point. If someone is nice to you, it is not the same as agreeing with your point of view. And if someone disagrees with you, it is not the same as they are attacking you, or them having some kind of dark agenda.

People are giving you the chance to interact on a scientific basis. Why not take the opportunity to either add your skills to others, or learn something for yourself? What do you have to loose?

I have challenged you several times, purely based on the actual science of this very topic, to look into how we can determine B with precision over the entire coil, without going via either a measurement or FEA analysis of Bl. I would like to add to that, that in an FEA analysis, you could calculate the integral normal B while having current applied to the coil. You could also calculate the resulting AC components. However, the AC components will not give you B, you will need to add them to the static simulation, and since the AC components are purely current based (because of the transformer coupling) there is really no way around extracting B from Bl, and not the other way around.

So what method would you use to avoid Bl from being the primary measured parameter, and B from being the derived parameter?

The entire argument that underpins the claims of the opening post rests on this. It can not be defended without addressing this part of the discussion. I expect something else than claims of you being under attack.

The user interface seems to work well for others, and it is a bit annoying to read posts with font size 30.

 

[Lars Risbo]

btw: beta is listed in our webshop for each driver.