China can build whatever you want...as long as you're watching.
Not sure why you're not giving credit to the objective data at hand. No other driver available for purchase has measured as well overall for its intended frequency range.
Summary: Excursion based measurements aren't as important for a pure midrange driver, but motor design is important regardless of the excursion of the voice coil.
You can still have a nice speaker with lesser spec'd drivers, but once you hear the difference....it's hard to go back.
Not sure why you're not giving credit to the objective data at hand. No other driver available for purchase has measured as well overall for its intended frequency range.
Summary: Excursion based measurements aren't as important for a pure midrange driver, but motor design is important regardless of the excursion of the voice coil.
You can still have a nice speaker with lesser spec'd drivers, but once you hear the difference....it's hard to go back.
It's just the combination of low + mids what makes those drivers good.
But as soon you're gonna go the direction of a multi-sub system that whole advantage goes outside the window extremely fast.
But even in a two way system, I know plenty of speakers that don't perform that far off, for a fraction of the price.
Just mount two of those (maybe back-to-back or something creative) and you'll be fine.
That's why I said, everything is relative.
I can also return the question as well.
Why should I give a lot of credit for something that isn't new and has been done before plus for a price to performance ratio that is really bad?
Find an investor, your niche and a good marketing story.
It just doesn't make any sense to me from an objective point of view.
Unless you have money burning in your pockets.
Ferrari has beautiful cars and top notch engineering.
I don't think most people even want it as a daily driver. Most people who own one, happily will admit it's just for the experience and kicks.
But as soon you're gonna go the direction of a multi-sub system that whole advantage goes outside the window extremely fast.
But even in a two way system, I know plenty of speakers that don't perform that far off, for a fraction of the price.
Just mount two of those (maybe back-to-back or something creative) and you'll be fine.
That's why I said, everything is relative.
I can also return the question as well.
Why should I give a lot of credit for something that isn't new and has been done before plus for a price to performance ratio that is really bad?
Find an investor, your niche and a good marketing story.
It just doesn't make any sense to me from an objective point of view.
Unless you have money burning in your pockets.
Ferrari has beautiful cars and top notch engineering.
I don't think most people even want it as a daily driver. Most people who own one, happily will admit it's just for the experience and kicks.
Actually 6 inches are even pretty limited when it comes down to a good directivity.
8 inches or 10 inchers perform better.
Their overall performance will be far better.
In fact even a decent cheap 10 inch with enough demodulation will outperform those numbers easily.
I have seen examples for just around 60-100 bucks.
Even less maybe if you search really well.
These bigger woofers also suffer a lot less from de 700-1500Hz distortion hump you see with almost any smaller driver.
Even the Purify suffers from it.
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btw, (I believe) not once was Kms (X) mentioned.
For instance (all-else-equal), a less stiff driver (its initial/resting "stiffness") is often better at lower level detail.
Ex. Scan Speak Revelator vs SB Satori (..where the Satori is better)
https://www.diyaudio.com/forums/multi-way/120505-significance-qms-11.html#post6640054
For instance (all-else-equal), a less stiff driver (its initial/resting "stiffness") is often better at lower level detail.
Ex. Scan Speak Revelator vs SB Satori (..where the Satori is better)
https://www.diyaudio.com/forums/multi-way/120505-significance-qms-11.html#post6640054
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Yes I did, I only called it Cms (x), but I meant Kms (x)
Unfortunately posts can't be edit anymore here
The compliance is only relevant around Fs and lower.
Above Fs the compliance won't be of any significance anymore.
Rms has a quite significant proportion to the Qms btw.
Kms (X) as plotted also describes the overall stiffness of the driver - it's not simply a matter of compliance below and near Fs. You could say the the mechanical compliance is more efficient with drivers having a lower resting resistance. (..ironically a lot of more efficient drivers have higher higher levels of resistance - though this is often done because they are usually "short-throw" designs and the designers wanted to ensure the VC remains near (preferably in) the gap at higher spls: basically mechanical braking to avoid damage and massive distortion.)
Also with respect to non-linear effects:
Beyond Thiele/Small DUMAX and Klippel Driver Measurement Systems | audioXpress
Also with respect to non-linear effects:
Beyond Thiele/Small DUMAX and Klippel Driver Measurement Systems | audioXpress
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When those mechanical parameters are being translated with the analogy to lumped circuit electrical domain, one could directly see that the compliance is basically non existing anymore above (roughly) 2 x Fs, for exactly the same reason the capacitance is non-existing anymore above 2 x Fs in a RLC resonator.
The biggest difference between the two, is that the compliance is a lot less linear in practice.
But they ARE exactly the same things, and will behave the same way.
Above the Fs the inductance becomes more and more dominant, which is the equivalent as the Mass in the mechanical domain.
So for everyone who is confused about all of this, just plot the contribution of every element of a RLC circuit and study its behavior.
This can also be measured when you kind of "fixate" the suspension of a speaker.
Above (again roughly) 2 x Fs the response of the speaker stays basically the same.
In physics and engineering, often the phrase "Everything has to comply with the Law of Conservation of Misery" is being used.
The compliance of a driver is an extremely good example of this.
The reason why it is such a thorn in the eye, is because the compliance is not the stiffness, it is 1 over the stiffness, or in other words, 1/x.
The consequence of this is that not only the curve shoots to infinity around zero, but the curve is also extremely non-linear.
To make it even more miserable, not only the spider works against you because of the shape (ok, can be fixed with progressive spiders to some extend), but rubber materials are the worst things in the world if it comes down to non-linear behavior.
All kinds of weird things happen with different temperatures, things get stiffer when they move faster and it gets even more wild when additives are being used to keep everything supple.
So another good practice is just simply don't use a speaker (subwoofer) under its Fs.
Or maybe like to maximum 0.75-0.8 x Fs absolute maximum.
And yes, the compliance will always have some effect as soon as there is a bit of cone excursion.
But as you can see in the graphs, around 2 x Fs (roughly 60Hz in this case), they are at least an order of magnitude (or more) lower.
The graphs are completely dominated by BL(x) and a little bit of Le(x)
When a proper highpass filter is being used, this number will even drop much much more.
So it even shows exactly what one would expect from theory.
The capacitance also doesn't drop all of a sudden.
I am trying to remember the electrical analogy with excursion, but it has been a while.
My feeling says charge or stored energy or around those lines.
The biggest difference between the two, is that the compliance is a lot less linear in practice.
But they ARE exactly the same things, and will behave the same way.
Above the Fs the inductance becomes more and more dominant, which is the equivalent as the Mass in the mechanical domain.
So for everyone who is confused about all of this, just plot the contribution of every element of a RLC circuit and study its behavior.
This can also be measured when you kind of "fixate" the suspension of a speaker.
Above (again roughly) 2 x Fs the response of the speaker stays basically the same.
In physics and engineering, often the phrase "Everything has to comply with the Law of Conservation of Misery" is being used.
The compliance of a driver is an extremely good example of this.
The reason why it is such a thorn in the eye, is because the compliance is not the stiffness, it is 1 over the stiffness, or in other words, 1/x.
The consequence of this is that not only the curve shoots to infinity around zero, but the curve is also extremely non-linear.
To make it even more miserable, not only the spider works against you because of the shape (ok, can be fixed with progressive spiders to some extend), but rubber materials are the worst things in the world if it comes down to non-linear behavior.
All kinds of weird things happen with different temperatures, things get stiffer when they move faster and it gets even more wild when additives are being used to keep everything supple.
So another good practice is just simply don't use a speaker (subwoofer) under its Fs.
Or maybe like to maximum 0.75-0.8 x Fs absolute maximum.
And yes, the compliance will always have some effect as soon as there is a bit of cone excursion.
But as you can see in the graphs, around 2 x Fs (roughly 60Hz in this case), they are at least an order of magnitude (or more) lower.
The graphs are completely dominated by BL(x) and a little bit of Le(x)
When a proper highpass filter is being used, this number will even drop much much more.
So it even shows exactly what one would expect from theory.
The capacitance also doesn't drop all of a sudden.
I am trying to remember the electrical analogy with excursion, but it has been a while.
My feeling says charge or stored energy or around those lines.
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Note:
Most drivers are in-box - and that changes compliance and Fs. You can also have "wobble" generating non-linearity when in-box.
2x Fb - could be higher than anticipated, particularly in a dedicated midrange.
In any event, this just concerns non-linear distortion - which is often (practically speaking) the least important result from a loudspeaker. (..not that it's un-important, just not nearly as-important as many other design issues.)
Most drivers are in-box - and that changes compliance and Fs. You can also have "wobble" generating non-linearity when in-box.
2x Fb - could be higher than anticipated, particularly in a dedicated midrange.
In any event, this just concerns non-linear distortion - which is often (practically speaking) the least important result from a loudspeaker. (..not that it's un-important, just not nearly as-important as many other design issues.)
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Vent tuning is the new Fb.
Notably with a bass reflex design the higher freq. impedance peak tends to be a Bl thing with very little of it having to do with Compliance: instead the port at that higher peak Impedance freq. mechanically damps the motion of the driver. (..and basically shifts the compliance problem to the lower peak Impedance freq. - where it's worse because it causes greater cone excursion unless it has a suitable high-pass filter well above that lower freq. OR if playback material doesn't just go that low at average spl's.)
Like part of b_force's conclusion: I prefer to have midranges with high-pass filters about 2 octaves above Fb.. BUT that's Fb in relation to a bass reflex design, and specifically with a lower tuning freq. and in a substantively larger enclosure than would ordinarily be an "aligned" sealed enclosure. I also prefer deeper enclosures for mid.s along with the vent exiting the rear of the loudspeaker.
Notably with a bass reflex design the higher freq. impedance peak tends to be a Bl thing with very little of it having to do with Compliance: instead the port at that higher peak Impedance freq. mechanically damps the motion of the driver. (..and basically shifts the compliance problem to the lower peak Impedance freq. - where it's worse because it causes greater cone excursion unless it has a suitable high-pass filter well above that lower freq. OR if playback material doesn't just go that low at average spl's.)
Like part of b_force's conclusion: I prefer to have midranges with high-pass filters about 2 octaves above Fb.. BUT that's Fb in relation to a bass reflex design, and specifically with a lower tuning freq. and in a substantively larger enclosure than would ordinarily be an "aligned" sealed enclosure. I also prefer deeper enclosures for mid.s along with the vent exiting the rear of the loudspeaker.
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Forgive misuse of f's lol
According to your post above, non linear distortion isnt worth addressing? Or am I taking you too literally? Otherwise the idea would be to stop running from fb (moving xo's 2x above etc) and to lower fb via tuning lower....
I have thread on here suggesting that to design a vented enclosure (tl,br for example) for max sound quality, one must approach tuning no differently than horn philosophy where XO is 1.5-2x cutoff of the horn...
Ive been learning recently that people are actually found this rule in order to successfully implement low order xover's, But this more technical ideology that lines up with the same type of tuning practices cannot be coincidental and the pioneers must've had this in mind…
I have been on the fence for a very long time about a closed enclosure versus an enclosure that is vented and tuned to 1/2 of the desired lowest note of the intended bandwidth... One thing that strikes me as a possible negative is adding more points of source....
According to your post above, non linear distortion isnt worth addressing? Or am I taking you too literally? Otherwise the idea would be to stop running from fb (moving xo's 2x above etc) and to lower fb via tuning lower....
I have thread on here suggesting that to design a vented enclosure (tl,br for example) for max sound quality, one must approach tuning no differently than horn philosophy where XO is 1.5-2x cutoff of the horn...
Ive been learning recently that people are actually found this rule in order to successfully implement low order xover's, But this more technical ideology that lines up with the same type of tuning practices cannot be coincidental and the pioneers must've had this in mind…
I have been on the fence for a very long time about a closed enclosure versus an enclosure that is vented and tuned to 1/2 of the desired lowest note of the intended bandwidth... One thing that strikes me as a possible negative is adding more points of source....
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Interesting and very good question.
Never thought of it.
But I think we can basically approach the vent similar as two way system.
One part of the response is done by the vent, the other part done by the woofer. In between they cross each other and combine.
At the port Fs the cone excursion goes almost to zero (or is very small)
At that point the acoustic power is completely done by the port.
Or well , rather by the whole helmholtz resonator, but you get what I mean I think.
0.5 * Fs sound quite reasonable, maybe around 0.8 * Fs if you really wanna optimize.
Obviously this all just in theory.
On the other hand, if follows the same idea of just not using the woofer underneath the Fs, since that's were bad things start to happen.
Al that being said, keep in mind that distortion levels can be pretty high at lower frequencies.
10-20% is not problem in most cases, even more so when this is mostly 2nd order.
It also really depends on the design, max passband, fs linear response and groupdelay. (mostly a groupdelay that isn't to erratic)
So what I sometimes do, is to make a roll-off with a Q of 0.5
At that point a BR should (in theory) sound very similar to a closed box.
(not taking other port issues into account of course)
The real question is, where actually the REAL trouble starts.
Unfortunately even Klippel doesn't give and show that answer.
I have seen other research that clearly shows that really weird things can happen with frequencies under Fs.
Depending on the kind of woofer and the whole suspension.
But for example, instead of the compliance going up (stiffness down), it starts to do the opposite, depending on the frequency.
Sometimes a whole shift can be measured. So the suspension is first stiffer, becomes more supple, and later will get more stiff again etc.
The point is, we just don't know what happens.
Some speakers don't seem to have many issues, or very little.
From that train of thought is my whole idea of not using a speaker beneath its Fs.