21 posts ahead of you.
I would greaty disagree to what they wrote in that document. Anybody to discuss each aspect in a civil way? 🙂
There was a real world improvement in max usable throw with xbl.
But (at least with some implentations) are not without issues. In my particular experience (SDX7 & FR/WR125) they have no warnings against banging into the back plate making an ugly "fart".
So i tend to use them in sealed boxes. SDX7 is/was one of my favorites (it did need at least a minimum amount of work 1st), and my subs are a pair of sealed push-push SDX10 (a very nice woofer, with good HF extention (for a sub)) making them easier to mesh with the full ranges i typically use.
Dan Wiggins is a smart guy.
dave
Adire was Dan Wiggins and David Hyre, FWIW. I seem to recall the original group buy for the Shiva drivers that put the predecessor, Avatar, on the map.
I got 8 of those… and went down to Avatar/Adire to pick them up… a nice get together.
dave
'Fast' and 'slow' are a function of the mass corner of the driver.
(Fs/Qes)*2=mass corner.
Think of the mass corner as a kind of horsepower-to-weight ratio for loudspeakers.
I think you will find fast and slow are determined by the inductance of the voice coil which limits the slew rate, hence the rise time of the current which can move the speaker at higher frequencies. Although the mass is relevant, it's trivial to the amount of force that could be available to move the mass if the inductance is lowered.
I would greaty disagree to what they wrote in that document. Anybody to discuss each aspect in a civil way? 🙂
If you have a point to make than make it.
The starting point is disproving the zoomed in graphs showing impulse response of:
a. unmodified driver
b. same driver with mass added
c. same driver with inductance increased.
There's no point in civilly discussing opinions, opinions are useless and the paper states it's case in that one graph in a very factual and scientific manner. So disprove that graph if you don't agree. In some type of scientific manner.
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But (at least with some implentations) are not without issues. In my particular experience (SDX7 & FR/WR125) they have no warnings against banging into the back plate making an ugly "fart".
So i tend to use them in sealed boxes. SDX7 is/was one of my favorites (it did need at least a minimum amount of work 1st), and my subs are a pair of sealed push-push SDX10 (a very nice woofer, with good HF extention (for a sub)) making them easier to mesh with the full ranges i typically use.
Dan Wiggins is a smart guy.
dave
Some drivers hit a hard limit, but these days Bl is linear for such incredible distances the suspension is increasingly becoming the soft limit. Hitting the suspension limits isn't going to sound nice either but at least you won't damage anything unless things get way out of hand and you start ripping parts and glue joints apart.
Wiggins' work wasn't all that different than stuff that came before. He was successful in designing, patenting, licensing and creating a huge marketing buzz but I don't think he had any real new IP that was much different than stuff that came before.
He's also been caught cheating in xmax specs on products he's designed.
Wiggins' work wasn't all that different than stuff that came before.
There are quite a few patented ways of trying to do the same thing… people looking for different ways so that they can be patented & licenced.
dave
Wrong. He can't just drop m from equation 2. Very sloppy math. He goes from f=ma right to f=a. Not to mention, it doesn't make sense. Same coil, same current same force. Same force different mass, different acceleration.
Wrong. He can't just drop m from equation 2. Very sloppy math. He goes from f=ma right to f=a. Not to mention, it doesn't make sense. Same coil, same current same force. Same force different mass, different acceleration.
Agree.
No experiment, even ones that look pretty clean, can be taken at face value uncritically. Hard to say how representative or meaningful was the rather small woofer he tested.
The Olsen/Beranek model with a static inductance seems odd, and even when you diddle-in the later research (I forget the researchers) with variable inductance (not sure what the real-world model of THAT is). Doubly hard to figure how to correctly measure a value to that inductance for a coil moving about with variable back-EMF.
Of course, I am no fan of the 100 year old Rice-Kellogg device.
Ben
Wrong. He can't just drop m from equation 2. Very sloppy math. He goes from f=ma right to f=a. Not to mention, it doesn't make sense. Same coil, same current same force. Same force different mass, different acceleration.
If the f is enough to a the m as fast as it needs to go (which I'm pretty sure is the case with most if not all moving coil drivers) then the m makes little or no difference.
Regardless, I don't speak math and don't care even a bit about formula 2 or how he altered it to get to formula 3 and 4.
What I care about is the measurement. The zoomed in impulse measurement.
Argue the sloppy math all you like, let's see someone redo this experiment and post some measured info that contradicts the impulse response in the paper.
That paper all boils down to that one graph, in fact you could totally ignore the entire paper except for that graph and get all the intended information.
As far as I know, a thesis has been presented, those that wish to debunk it are responsible for providing the burden of proof.
Agree.
No experiment, even ones that look pretty clean, can be taken at face value uncritically. Hard to say how representative or meaningful was the rather small woofer he tested.
The Olsen/Beranek model with a static inductance seems odd, and even when you diddle-in the later research (I forget the researchers) with variable inductance (not sure what the real-world model of THAT is). Doubly hard to figure how to correctly measure a value to that inductance for a coil moving about with variable back-EMF.
Picking holes in the method is meaningless. Provide your own proof that contradicts the information presented, otherwise all the nitpicking is just speculation and very likely unwarranted.
Of course, I am no fan of the 100 year old Rice-Kellogg device.
Ben
Oh, I don't think anyone is oblivious to that fact, regardless of the more pertinent fact that you are currently using two 70 year old moving coil drivers in your "subwoofers" currently, and the moving coil drivers of today are MUCH different than they were 100 or even 70 years ago. The wheel as a concept is far older than 100 years, do you have a problem with that based solely on the age of it's invention also? At the time of it's inception it was very likely just a crude round object like a stone or log that rolled, but just like moving coil drivers, today's tech in wheels is a bit better than it used to be.
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Your first line dosnt make sense. And if he is fudging the math (physics) to explain his measurements than maybe his measurements are wrong. But what do you care.
Your first line dosnt make sense. And if he is fudging the math (physics) to explain his measurements than maybe his measurements are wrong. But what do you care.
Of course the first line makes sense. If you have enough force to accelerate the mass as fast as it needs to go then the mass is irrelevant. The mass doesn't need to go infinitely fast, it just needs to be quick enough to give a decent impulse. As far as I know, all moving coil drivers can give a decent impulse except maybe the high inductance ones.
Picking holes in his physics is far from meaningless
Ben wasn't picking holes in his physics. He said -
The Olsen/Beranek model with a static inductance seems odd, and even when you diddle-in the later research (I forget the researchers) with variable inductance (not sure what the real-world model of THAT is). Doubly hard to figure how to correctly measure a value to that inductance for a coil moving about with variable back-EMF.
How is it hard to measure inductance? This is exactly what the Klippel machine does - it measures inductance and plots it vs excursion. It spits out a chart that looks very much like a bell curve showing inductance linearity vs excursion.
And if you want to know inductance vs frequency, that's easy too, any t/s measurement software can do that from a measured impedance curve. WT2, WT3, DATS, LIMP (ARTA), REW, can all measure inductance vs frequency.
So we can easily measure inductance vs frequency AND inductance linearlity vs excursion.
Or maybe Ben was only arguing how t/s parameters are presented in yet another backhand assault on simulators and their relevance.
Other than that, all Ben said was "
No experiment, even ones that look pretty clean, can be taken at face value uncritically. Hard to say how representative or meaningful was the rather small woofer he tested.
So we have a criticism, a misconception about being able to measure inductance, and no proposed solution.
How is that picking holes in his physics?
Now on to what you said. You offered a criticism to a simple formula but did not prove what was done in the paper has any relevance at all.
Argue the zoomed in impulse graph, preferably with a measured graph of your own. Short of that you can offer nothing of any value.
What I don't get is this is only correct in a vacuum since most of the force pushes air.
The mass in the formula can be expressed as the mass of the cone alone (Mms) or as the mass of the cone with the mass of the air in it's way combined (Mmd) as the math was well known decades ago.
What you need to do is prove the mass is any significant problem for the force to accelerate. The paper shows it's not in the zoomed in impulse measurement. Argue the paper if you like, but present some evidence of your own to back you up.
I think you will find fast and slow are determined by the inductance of the voice coil which limits the slew rate, hence the rise time of the current which can move the speaker at higher frequencies. Although the mass is relevant, it's trivial to the amount of force that could be available to move the mass if the inductance is lowered.
No, not really. If you look at the impedance curve measurement of some speakers, especially bass speakers, you´ll find that most of the time the main domain is RESISTANCE, and in places where it becomes complex load, you don´t really see adequate drops in frequency response, because at these peaks, the system is efficient. Also for bass speakes playing low frequencies, inductance is less and less important. Closer to the DC voltage, it doesn´t matter how large the inductance is.
If you have a point to make than make it.
The starting point is disproving the zoomed in graphs showing impulse response of:
a. unmodified driver
b. same driver with mass added
c. same driver with inductance increased.
There's no point in civilly discussing opinions, opinions are useless and the paper states it's case in that one graph in a very factual and scientific manner. So disprove that graph if you don't agree. In some type of scientific manner.
There are three problems with it.
1) To disprove every single aspect of it, it would take me a lot of time, and your time too, because it would be too long to read. So long that I´m afraid that about nobody will read.
I didn´t mention "I think" to make it an opinion. I disagree with the facts arrangement.
2) He who writes some stuff online and openly, is not automatically the same person as he who is right. That is very ill adviced thought process. People never learn this one. I don´t really care if I loose a debate. It is not fight for a life. I am happy to know things compared to those who think they know.
3) I don´t agree with just unusable facts. It´s mindblowing to see boasting about newtonian physics, and then use it totally without the real context. It left me speechless for some time. I don´t even know where to start.
There is no problem with their description in "reaction speed" as is. They have this one right. The problem is how they use it.
There is problem with actual speed measured in time domain.
Using newtonian physics and some advanced math, if you follow absolute position of the speaker cone, you must know that while a = Fm, the current position of the speaker will have to be different in time equal to quarter, or half of the period of sinusoidical signal with different mass. The actual usable outcome will usually be less sensitivity. This doesn´t give us much of the problem if we don´t see in detail, because wrongly pointed, If you add power, you bring the speaker to the same potential of force and acceleration, making things equal in the output sound pressure level and frequency response. 1) no, 2) not the topic.
I don´t like analogies with cars but here it is. Once you put so much weight and so much power to the larger and heavier car to make it as fast as small and light car, you will end up 1)blowing the tyres from the weight when standing 2) being not able to transfer that power on the road trough wheels. It will spin, slide, drift. 3)not able to make so much power from conventional engine.
The same happens with speakers. You reach different behavior of the speaker suspension system, thermal losses, and if everything holds, bragging about infinity term, the air would liquify, and our system would not work as a sound system anymore 🙂. That I don´t consider usable explanation from them.
Now back into the main topic:
The speaker will have most efficiency at resonant frequency. So it is easy to move it at Fs. I´m not sure why measured impedance is so high at this frequency. Anyway, you add another spring with its resonant frequency. Accoustical circuit, a bassreflex. This one will work at the same frequency, but in directly the opposite phase. This one is driven by the speaker, but, it is slightly reciprocial device, otherwise it wouldn´t have resonant frequency, It all needs to be driven by the speaker. Now what if the speaker is weak? Easy. It will not stop the resonation fast enaugh when you want it. The -10db point will be rached in longer time. Using infinite force of the speaker to stay still when needed, the speaker will do that. Once you don´t have the force in the motor to keep the cone still, you rely on the restoring force of the speaker suspension system, which is not absolutely strong, and the speaker will move with resonations, damping it somehow with each cycle. Stronger speakers will damp the signal to the certain value using less cycles = less GD, less boom.
The same as when heavy car needs to bake/stop. Depending on the brake power and road-to-tyres area, it will brake sooner or later. Guess what! Lighter car will most likely brake sooner, because it has better breaking power-to-mass ratio. The same works in tuned circuit for strong and weak speakers with stiff or weak suspension.
From my experience: While this is the problem, it is not the main problem. Using strong parametric EQs, one can alter the frequency response and -10db point in time so he perceives it as mostly good signal - mostly.
Not a solution, but good enaugh for weak and cheap systems.
But it is generally not 100% situation, and not healthy. It lowers the cone excursion at these boomy frequencies. You have lowered cone excursion from using bassreflex circuit too. Once you input less power to the speaker only at certain frequencies, it moves even less, then cools itself less, and burns more likely. You can help it by boosting sub-bassreflex tuning frequencies hoping these will be present in the signal, to make it into accoustical short and make the cone move, but it is obviously not as good as healthy good solution from the beginning.
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There is no problem with their description in "reaction speed" as is. They have this one right.
That's the thesis of the paper right there, and you agree with it. We could stop there but I will address some of your other points.
While it is true that if you use a resonant enclosure (ported box) and a driver with a qts of greater than about .5, there will be a time delay associated with stopping the cone. This is well known. And it's not an issue if you design properly.
Keep the tuning below 40 hz and the ringing associated with the resonance will be completely swamped by the ringing associated with the room rta. And since most of what we hear is frequency response, if you design or eq to have a flat in room frequency response it will not sound "slow" even if there is a couple ms of ringing associated with the resonance. And the lower you tune the less of a problem it is, as the cycles get longer in time and human hearing gets less sensitive.
The analogy with cars is interesting, but we are talking about small changes in weight vs force, not large changes that would cause tires spinning due to not being able to transfer the power to the ground. I would agree if Mms was out of control, like a kg or more, but that isn't the case. The biggest drivers have high Mms (like 600 g or a bit more) but they also have huge motors that can throw that weight around forcefully enough. The problem is inductance, since those large coil speakers are synonymous with high inductance.
If you want to know where to start in disproving the paper, you need some measurements to show that invalidate the measurements shown in the paper. But since you specifically agreed with the thesis of the paper in the sentence I quoted here that's going to be hard for you to do. It seems like you have more of a problem with their bold use of math and physics (that may be slightly off the mark) but don't actually disagree with the thesis or the measurement.
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