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"The floating cone driver"

Cosmik said:
I'm not convinced there's much wrong with conventional cone speakers - and you could use things like closed loop control at the lower frequencies and/or pre-distortion at the higher. But I like the idea of thinking radically. But these people give away their audiophile fetish-based thinking by promoting their 'most linear speaker in the world' partnered with the least linear amplifiers in the world - and they use the most non-radical option of the passive crossover, inevitably leading to various distortions of the waveform despite the potential performance of their (vapourware?) driver.
Click to expand...

Controlling cone vibration modes must be easier in a conventional loudspeaker with the better support(rigidity) and damping of transverse waves by the outer surround.

A lightweight and more rigid cone could be possible using graphene: https://www.nextbigfuture.com/2017/...-coming-march-2018-and-devices-to-follow.html
 
Wombat said:
Controlling cone vibration modes must be easier in a conventional loudspeaker with the better support(rigidity) and damping of transverse waves by the outer surround.
Click to expand...

Why do you think so? I have no technical knowledge on this. But intuitively, the technical claims here make sense to me - that a loudspeaker cone which is controlled "electro-magnetically" (whatever that means) can be better controlled than pure magnetic (edit: mechanical) damping through spider and surround.

What doesn't make sense to me, though, is the claim that the lost energy in the spider and surround somehow results in a loss of detail. Isn't it just the case that the driver needs more current because energy is lost? Seems like a strange assumption that this extra current contains unique information that never reaches the cone?
 
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oivavoi said:
Why do you think so? I have no technical knowledge on this. But intuitively, the technical claims here make sense to me - that a loudspeaker cone which is controlled "electro-magnetically" (whatever that means) can be better controlled than pure magnetic damping through spider and surround.

What doesn't make sense to me, though, is the claim that the lost energy in the spider and surround somehow results in a loss of detail. Isn't it just the case that the driver needs more current because energy is lost? Seems like a strange assumption that this extra current contains unique information that never reaches the cone?
Click to expand...
Indeed. Their graphs which show that their driver is linear, whereas a conventional driver isn't, don't have any corroborating evidence for that. We know and it's well understood that loudspeakers compress at high levels, in part due to thermal effects and in part due to suspension non-linearity as it runs out of excursion. However, I've never seen any suggestion that a loudspeaker is non-linear at low levels. It sounds like they're suggesting the loudspeaker is 'sticky', like limiting friction, that stops it moving until a certain minimum force is applied.
If that were true, then it would affect microphones as well, which in the case of dynamic microphones, are just like loudspeakers in reverse. Again,not anything I've ever seen suggested in Pro circles.

S.
 
sergeauckland said:
Indeed. Their graphs which show that their driver is linear, whereas a conventional driver isn't, don't have any corroborating evidence for that. We know and it's well understood that loudspeakers compress at high levels, in part due to thermal effects and in part due to suspension non-linearity as it runs out of excursion. However, I've never seen any suggestion that a loudspeaker is non-linear at low levels. It sounds like they're suggesting the loudspeaker is 'sticky', like limiting friction, that stops it moving until a certain minimum force is applied.
If that were true, then it would affect microphones as well, which in the case of dynamic microphones, are just like loudspeakers in reverse. Again,not anything I've ever seen suggested in Pro circles.

S.
Click to expand...

They are referring to Klippel, who's written quite a lot about distortion and linearity in loudspeakers: https://www.klippel.de/fileadmin/_m...linearities–Causes_Parameters_Symptoms_01.pdf

I read that paper some while back, and understood less than half of it. I do have a sense that there's some sound reasoning behind their design though, even though they are audiophiling it up by adding flowery language. My layman understanding is that it is indeed higher amplitudes which causes most problems for loudspeaker drivers. But I don't think this is only a problem for what we think of as "loud" levels, because music contains transient peaks which can be much louder than the continuous tones. There is also very little published research into dynamics and trasients when it comes to sound reproduction in the home.

I also have a sense that this is a real problem, because there are several manufacturers I regard as firmly placed in the the no bullshit camp who are concerned with the linearity of loudspeaker drivers. Dutch & Dutch apparently chose drivers for their 8C speaker out of considerations about "pistonic" movement, in order to achieve a smooth and linear reproduction of the signal. Their main engineer had this to say about their driver selection over at gearslutz:

"Let's first consider drivers in terms of achieving flat and smooth response. In order to achieve maximally flat and smooth response, you need drivers that are pistonic in their passbands, with no resonances. Size in itself is not relevant. In passive loudspeakers non-rigid but well-damped drivers make sense, because they are generally easier to deal with in the crossover. Pistonic, resonance-free drivers ultimately offer greater clarity and in a DSP-based system their out-of-band quirks are easily dealt with".

And I received this email from M. Kravchenko, a manufacturer who makes loudspeaker drivers for different companies. He explained to me why he had designed a new woofer for the Morrison omnis:

"The existing woofer is a pretty good driver so it is not to easy to improve upon. What I did was change the motor from XBL to a complete underhung system. The XBL motor is kind of a a solution looking for a problem. Specifically it trades efficiency for a flatter BL motor force curve. It was a clever way around the truly great engineering feat of a split coil motor patented by B&C loudspeakers. Clever in a sort of should we have done it way? It is a complicated way to trade off different strengths and weaknesses in a loudspeaker motor. It also introduces more tha nit's share of potential problems. The top part of the motor movement is not as strong as the bottom part as a simple example. The motor parts are more expensive to make and they also add in a break in the magnetic circuit right where you do not want one. So I changed the design to underhung. Solved quite a few problems. "

I'm not going to claim that I understand what all this means. But my take-away is that there are trade-offs in how different drivers work.
 
Drivers seem to be designed very much in isolation, as do amplifiers, as do DACs. I can't help but think that if this were a general engineering problem, and there was obviously something wrong with the previous 100-year old technology, people would be more interested in how software and electronics could be harnessed and integrated to improve on it. The closed loop feedback method is a pretty obvious one..?

Active crossovers eliminate a lot of problems. DSP mops up some more.

There are different ways of dividing the problem up. If the system is compatible (not sure about omni), electronics allow more 'ways' to be used without pain, reducing many of the problems that surface when a driver is being driven at its outer limits of power and frequency. It really is just a question of making one or more things accelerate in time with a signal. At low levels and over their ideal frequency range, normal drivers do this pretty well. DSP provides a 'scientific' way of coordinating them - it is not just a replacement for passive crossovers.
 
Cosmik said:
Drivers seem to be designed very much in isolation, as do amplifiers, as do DACs. I can't help but think that if this were a general engineering problem, and there was obviously something wrong with the previous 100-year old technology, people would be more interested in how software and electronics could be harnessed and integrated to improve on it. The closed loop feedback method is a pretty obvious one..?
Click to expand...

Mostly agree. But I don't think the present direction of the audio industry is indicative of what may or may not be real problems... after all, passive crossovers are still the norm, many decades after people figured out that there could be a better way.
 
oivavoi said:
Mostly agree. But I don't think the present direction of the audio industry is indicative of what may or may not be real problems... after all, passive crossovers are still the norm, many decades after people figured out that there could be a better way.
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I think that the continuance of passive loudspeakers is entirely led by marketing, not technical.
Firstly, Dealers don't like actives because they're a bigger ticket item, so less volume. Secondly, dealers don't get the opportunity for upgrades on amplifiers and cables. Enthusiasts don't like them because they can't fiddle with 'speaker cables and amplifiers and stuff, and don't have an upgrade path, no second power supplies or bi-amp amplifiers.
The only people who like actives are those who understand the technicalities, or who prefer fewer boxes and a neater presentation.

So, if I were a loudspeaker manufacturer looking for the very high end, passive makes sense. They could very easily have put in a two-way DSP crossover and Class D amplifiers for trivially little extra cost in that external case, but would it then have had Audiophile credibility? Maybe if the amplifiers had been SETs instead of Class D.......

S.
 
oivavoi said:
Why do you think so? I have no technical knowledge on this. But intuitively, the technical claims here make sense to me - that a loudspeaker cone which is controlled "electro-magnetically" (whatever that means) can be better controlled than pure magnetic damping through spider and surround.
Click to expand...

You only control the driving point of the cone. Picture a drum head and note that you control how the stick hits it but not how the waves propagate across the head (neglecting putting your hand on it or otherwise mechanically damping it). When you drive a speaker from the center (or any single point), the driver (amplifier) does not control how the membrane itself behaves. Vibrational modes occur in the cone related to the frequency of the applied signal, amplitude of signal, and mechanical properties of the cone. An infinitely stiff cone would move as a single unified surface, but real cones flex a little when you push on them and modes (patterns) develop in the cone that can cause distortion. The spyder and surround can dampen these modes, but you do not have that mechanical damping without those elements.

Pick up a piece of paper by one edge and flap it -- the paper moves in response to your hand, flapping wildly and somewhat uncontrollably. Switch to a piece of cardboard, and it tends to move more as a single sheet, but move your hand fast enough and hard enough (larger amplitude) and it begins to flex as well. Not much your hand can do about it if you want the sheet to move at that rate (speed, frequency) and amplitude. If you put a strip of surround material at the other end, then you can keep the paper or cardboard from flapping as wildly. Without that, there is less ability to dampen and control what the paper/cardboard/speaker cone is doing. So one question is how they control cone modes? My guess is they rely on the material to be stiff enough to not mode significantly in normal operation, and/or perhaps they are using the air channels to provide some mechanical damping.

HTH - Don
 
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DonH56 said:
You only control the driving point of the cone. Picture a drum head and note that you control how the stick hits it but not how the waves propagate across the head (neglecting putting your hand on it or otherwise mechanically damping it). When you drive a speaker from the center (or any single point), the driver (amplifier) does not control how the membrane itself behaves. Vibrational modes occur in the cone related to the frequency of the applied signal, amplitude of signal, and mechanical properties of the cone. An infinitely stiff cone would move as a single unified surface, but real cones flex a little when you push on them and modes (patterns) develop in the cone that can cause distortion. The spyder and surround can dampen thee modes, but you do not have that mechanical damping without those elements.

Pick up a piece of paper by one edge and flap it -- the paper moves in response to your hand, flapping wildly and somewhat uncontrollably. Switch to a piece of cardboard, and it tend to move more as a single sheet, but move your hand fast enough and hard enough (larger amplitude) and it begins to flex as well. Not much your hand can do about it if you want the sheet to move at that rate (speed, frequency) and amplitude. If you put a strip of surround material at the other end, then you can keep the paper or cardboard from flapping as wildly. Without that, there is less ability to dampen and control what the paper/cardboard/speaker cone is doing. So one question is how they control cone modes? My guess is they rely on the material to be stiff enough to not mode significantly in normal operation, and/or perhaps they are using the air channels to provide some mechanical damping.

HTH - Don
Click to expand...

Thanks Don! That was very clarifying!
 
Here's an interview:


Seems to be a static demo when they show the speakers and music is coming off the video.
 
sergeauckland said:
Indeed. Their graphs which show that their driver is linear, whereas a conventional driver isn't, don't have any corroborating evidence for that. We know and it's well understood that loudspeakers compress at high levels, in part due to thermal effects and in part due to suspension non-linearity as it runs out of excursion. However, I've never seen any suggestion that a loudspeaker is non-linear at low levels. It sounds like they're suggesting the loudspeaker is 'sticky', like limiting friction, that stops it moving until a certain minimum force is applied.
If that were true, then it would affect microphones as well, which in the case of dynamic microphones, are just like loudspeakers in reverse. Again,not anything I've ever seen suggested in Pro circles.

S.
Click to expand...
Yes. Normal dynamic drivers are "sticky" - stiction is the term I believe is used for this, has been discussed on a number of occasions. I learned that very heavy conditioning, by driving the suspension vigorously with the right music, overcomes this to a large degree - how this manifests is that the speakers have "no detail" when cold - only the "big sounds" are heard, the low level information is just not there; after conditioning, play the same track, and a whole new world opens up in terms of hearing fine details in the mix.
 
RayDunzl said:
Here's an interview:


Seems to be a static demo when they show the speakers and music is coming off the video.
Click to expand...


Shown in video in most photogenic position.


Pic below shows cone down:

file.jpg
 
sergeauckland said:
I think that the continuance of passive loudspeakers is entirely led by marketing, not technical.
Firstly, Dealers don't like actives because they're a bigger ticket item, so less volume. Secondly, dealers don't get the opportunity for upgrades on amplifiers and cables. Enthusiasts don't like them because they can't fiddle with 'speaker cables and amplifiers and stuff, and don't have an upgrade path, no second power supplies or bi-amp amplifiers.
The only people who like actives are those who understand the technicalities, or who prefer fewer boxes and a neater presentation.

So, if I were a loudspeaker manufacturer looking for the very high end, passive makes sense. They could very easily have put in a two-way DSP crossover and Class D amplifiers for trivially little extra cost in that external case, but would it then have had Audiophile credibility? Maybe if the amplifiers had been SETs instead of Class D.......

S.
Click to expand...

I agree, but I also think that the high-end industry has alienated much of its potential market with the profusion of expensive, ugly, and space-consuming boxes.

Impressed as I am with the 8Cs, I suspect that higher performance can be obtained with an even more integrated engineering approach and greater outward simplicity than that reflected in the 8Cs.

I keep hoping for a company to make that product, but high-end companies have two problems. First, they are too busy catering to the East Asian nouveau riche and the kinds of guys in the United States and Europe who have convinced themselves that golf is fun. Second, high-end companies (unlike pro-oriented companies such as D&D, Weiss, or Benchmark) tend not to employ real engineers or even people with minimal levels of musical knowledge or taste. I'm particularly pointing the finger at Wilson Audio here (no apologies), and I'd be happy to go into greater detail on a separate thread about their bad engineering and taste and the harm that they've inflicted on the hobby of serious music listening.
 
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soundArgument said:
I agree, but I also think that the high-end industry has alienated much of its potential market with the profusion of expensive, ugly, and space-consuming boxes.

I just bought a pair of Dutch & Dutch 8Cs, in part because I want better performance but also because I want fewer boxes. Further, my wife wants speakers that can go near the wall, and the 8Cs' DSP allows exactly that.

Impressed as I am with the 8Cs, I suspect that higher performance can be obtained with an even more integrated engineering approach and greater outward simplicity than that reflected in the 8Cs.

I keep hoping for a company to make that product, but high-end companies have two problems. First, they are too busy catering to the East Asian nouveau riche and the kinds of guys in the United States and Europe who have convinced themselves that golf is fun. Second, high-end companies (unlike pro-oriented companies such as D&D, Weiss, or Benchmark) tend not to employ real engineers or even people with minimal levels of musical knowledge or taste. I'm particularly pointing the finger at Wilson Audio here (no apologies), and I'd be happy to go into greater detail on a separate thread about their bad engineering and taste and the harm that they've inflicted on the hobby of serious music listening.
Click to expand...


I would advise that such a Wilson thread be run past this forum's lawyers first. :cool:
 
soundArgument said:
I happen to be a lawyer, and I'm way more expensive than any lawyers Wilson Audio can afford.
Click to expand...

Sounds like it could cost Amir more than his testing budget even if he wins.:eek:
You can win if you are nice about your criticism: https://en.wikipedia.org/wiki/Bose_Corp._v._Consumers_Union_of_United_States,_Inc.

Seriously, a plaintiff can usually choose to litigate in one or many of the legal jurisdictions that this publication appears in. It becomes a 'who has the resources to pursue the matter' issue but then that is how the law usually works, huh. :(
 
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I’d rather celebrate good engineering than give publicity to what some might call bad engineering practice ( in the way suggested, obviously we highlight bad practice when we find it in the testing). Being smart folk you will know that having a forum like this slag off a brand ( like say Wilson) really only reinforces the audiophools misconceptions and intrenches their way of thinking with more resolve than ever before.

Let’s be positive and celebrate go looking for the good and the great , celebrate that.
 
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