The Manipulated Vortex Waveguide speaker - the Event Horizon 210

0 Members and 1 Guest are viewing this topic. Read 34769 times.

JICRO

  • Jr. Member
  • Posts: 16
Re: The Manipulated Vortex Waveguide speaker
« Reply #60 on: 20 Mar 2014, 07:36 pm »
Hello Everyone,

For the readers here that would like to know more about what is under the hood in the MVW systems the patent application was published at the USPTO this month as US 2014/0060959. 

Anyone that would like a copy of the patent application, just let me know and I'll send you a copy.



All the best,

- Jim Croft



Duke

Hi Jim,

Good to hear from you!  I always enjoy your patent reviews in Voice Coil.  Thanks for posting this information, I was not aware of it, and for your offer to make a copy available to people. 

If anyone would like, here's a direct link to the patent application on the USPTO site:

http://www.google.com/patents/US20140060959


MJK

  • Full Member
  • Posts: 440
    • Quarter Wavelength Loudspeaker Design
My opinion.

Looks like a complicated folded transmission line speaker. Interesting design but not new physics. Manipulated Vortex Waveguide appears to be nothing more than clever marketing lingo.

Duke

My opinion.

Looks like a complicated folded transmission line speaker.

Yes, it does.   My first thought was that it not only looks like a complicated folded transmission line speaker, but a poorly designed one at that. 

My opinion...

Interesting design but not new physics.

Not until you take into account vortex shedding, and I don't know of a mathematical model for doing so, and as a result the design work is dominated by educated guesswork and trial & error at this point.  (I don't do any of the actual design work; Steve and Tom may use mathematical models that I'm unaware of.)

My opinion...

Manipulated Vortex Waveguide appears to be nothing more than clever marketing lingo.

It's both accurate and clever.   

One person might use the term Mass Loaded Transmission Line, and another person might say "Mass Loaded Transmission Line appears to be nothing more than clever marketing lingo."  The second person would be overlooking significant refinements that are not obvious. 

In my opinion, the MVW is a bigger advance over the transmission line than the MLTL is over a ported box. 

(In case anyone is wondering why I chose that example, it's because MJK is the inventor of the Mass Loaded Transmission Line.)

MJK

  • Full Member
  • Posts: 440
    • Quarter Wavelength Loudspeaker Design
Quote
One person might use the term Mass Loaded Transmission Line, and another person might say "Mass Loaded Transmission Line appears to be nothing more than clever marketing lingo."  The second person would be overlooking significant refinements that are not obvious.

ML TL  and the original ML TQWT are two catchy phrases I coined after mathematically modeling these tall ported cabinet designs. The designs had been round for many years without an accurate computer model for DIYers to use during the design phase, simple lumped parameter bass reflex models were not accurate. I invented nothing other then a neat catch phrase that was based on the physical behavior of the air in the enclosure, to be honest I threw it out there onto the Internet tongue in cheek and to my surprise it stuck and seemed to be generally accepted. Understanding the physics and putting together a computer model allowed many DIYers to design these tall cabinets, build them, and then measure the electrical impedance and SPL curves to find that what they had built performed as expected. No more trial and error designs, the loop is closed and the methods proved out. The physics are completely understood.

Quote
Not until you take into account vortex shedding, and I don't know of a mathematical model for doing so, and as a result the design work is dominated by educated guesswork and trial & error at this point.  (I don't do any of the actual design work; Steve and Tom may use mathematical models that I'm unaware of.)

So there is no mathematical model to predict vortex shedding, yet the claim is that this is the source for superior performance. I am not disputing the superior performance, if you say they sound great I trust your ears.

Over the past 15 years I have reverse engineered many different folded passage speakers (probably many 100's), some similar to the pictures in the patent (look at the old Lowther back loaded horn designs for example), once independent impedance and SPL measurements are presented in an independent review and a picture of the cross-section is shown that I can scale. If the picture and measured data is accurate then my TL based model predictions usually are very close. Based on this experience with TL models and looking at the pictures in the patent, I believe this enclosure is nothing more then a very creative TL application that may produce excellent bass output due to complicated standing waves generated by the unique geometry. The behavior of the air in the enclosure can only be accurately predicted by computer models. My TL experience tells me that there is no such thing as a "manipulated vortex waveguide", sorry. When there is enough independent information and measurements available I will probably reverse engineer this design and figure out how it works and if it can be improved, it should be a very interesting intellectual challenge.

Duke

So there is no mathematical model to predict vortex shedding, yet the claim is that this is the source for superior performance.

What I should have said is:  None of the loudspeaker models that I'm aware of take vortex shedding into account. 

I'm pretty sure that vortex shedding can be modeled, along with its acoustic implications.   The previously mentioned graduate-level text "Vortex Theory of Sound" by M.S. Howe goes over my head almost immediately, but the first paragraph is within my grasp:

"Vortex sound is the sound produced as a by-product of unsteady fluid motions. It is part of the more general subject of aerodynamic sound. The modern theory of aerodynamic sound was pioneered by James Lighthill in the early 1950's. Lighthill (1952) wanted to understand the mechanisms of noise generation by the jet engines of new passenger jet aircraft that were then about to enter service. However, it is now widely recognized that any mechanism that produces sound can actually be formulated as a problem of aerodynamic sound. Thus, apart from the high speed turbulent jet - which may be regarded as a distribution of intense turbulence velocity fluctuations that generate sound by converting a tiny fraction of the jet rotational kinetic energy into the longitudinal waves that generate sound - colliding solid bodies, aeroengine rotor blades, vibrating surfaces, complex fluid-structure interactions in the larynx (responsible for speech), musical instruments, conventional loudspeakers, crackling paper, combustion and combustion instabilities in rockets, and so forth all fall within the theory of aerodynamic sound in its broadest sense."

Distilling down that first paragraph a bit:

 "...any mechanism that produces sound can actually be formulated as a problem of aerodynamic sound. Thus... complex fluid-structure interactions in the larynx (responsible for speech), musical instruments, conventional loudspeakers, crackling paper, combustion and combustion instabilities in rockets, and so forth all fall within the theory of aerodynamic sound in its broadest sense." [emphasis in the original text]

Point being, the aerodynamic theory of sound, a subdivision of which is the vortex theory of sound, is a more general and all-encompassing theory of sound generation than are the loudspeaker models we are accustomed to.   So in a sense the inventors have unplugged from conventional loudspeaker models, gone up a level, and plugged back in, using loudspeaker motors & cones to generate the initiating energy.

I am not disputing the superior performance, if you say they sound great I trust your ears.

Thank you for the vote of confidence, in my ears if not in my grasp of acoustic science!  I'll take whatever I can get!!

Based on this experience with TL models and looking at the pictures in the patent, I believe this enclosure is nothing more then a very creative TL application that may produce excellent bass output due to complicated standing waves generated by the unique geometry.

One of the issues I ran into with transmission lines was cancellation at the frequency where the line length is equal to one wavelength, as at that frequency the energy from the terminus is 180 degrees out-of-phase with the energy coming from the front of the cone.  Various techniques can be used to mitigate this cancellation dip, but none of the ones I'm aware of are obviously applied in any of the MVW designs shown in the patent.  So if the enclosures were transmission lines, I think we'd expect to see that cancellation dip in the measured response. 

I haven't seen anything like the one-wavelength cancellation dip in my own measurements of MVW enclosures.   Now maybe that's for reasons other than the ones the inventors claim, but in watching them follow their vortex paradigm, I've seen them make improvements that I do not think would be predicted by any loudspeaker model I'm aware of.  That being said I certainly do not hold myself out as an expert on loudspeaker modeling.  But if the inventors' paradigm is useful in predicting (though not yet precisely modeling) performance of the MVW loudspeaker, whereas to the best of my knowledge other paradigms are not, then for now at least I'm subscribing to theirs. 

Anyway I don't blame you one bit for being skeptical; if I were in your position, I would be to the extreme.  The most I could ask of you or any other skeptic would be to not indulge in contempt before investigation.   
« Last Edit: 21 Mar 2014, 04:48 am by Duke »

*Scotty*

Here are some links to fluid dynamics modeling programs which could be used to analyze what is happening in the loudspeaker.
Open source freeware
http://www.openfoam.com/

http://www.macworld.com/article/1024399/tetruss.html
"TetrUSS is used in aerodynamics and fluid dynamics analysis, and has been used on major projects including High Speed Research / High Speed Civil Transport, Hyper-X, Abrupt Wing Stall, Mars Scout, Joint Strike Fighter and more. What's more, the software has been used in the civilian aerospace industry, academy, automotive, biomedical and civil engineering fields.

NASA research scientists and the Air Force Research Laboratory developed TetrUSS for their own use, and it has evolved into an unstructured-grid flow analysis and design Computation Fluid Dynamic (CFD) software system. It's available free of charge to U.S. entities, citizens and permanent residents. A free training course is even available at NASA Langley Research Center, as well."

Also fluid dynamics for your iPad
http://www.algorizk.com/
Navier Stokes equations
https://itunes.apple.com/nl/app/fluid-dynamics/id382274493?mt=8

Check iTunes for the apps
Scotty

James Romeyn

  • Industry Participant
  • Posts: 3294
  • James Romeyn Music and Audio, LLC
    • James Romeyn Music and Audio, LLC
Scotty is the real deal.  I can't believe how cool is some of the stuff I've learned from his posts.  His range of references is huge, useful, and informative.  The post above is more of the same.  I'm interested in his observations re. MVW, both regarding the math (as he learns about it) and audition if/when he hears it. 

Scotty, you might consider joining Talk Bass toward finding someone local employing Mike Arnopol's MVW Bass Cabinets.  An ideal audition would include A-B test with same "head" amp, MVW cabinet vs. non-MVW cabinet.  5-string bass lowest string is most often tuned to low B, 31 Hz fundamental (though the first harmonic is higher in output vs. the fundamental).  Mike reports MVW is the only system capable of reproducing 16th-note open low B with clarity of each transient.   

Sorry to repeat Mike's adage again, but there appear to be two MVW groups, skeptics and those who heard it.

The same year, maybe late 80s, I heard at The Riviera in Las Vegas CES, both the Duntech Sovereign and hugest flagship IMF Transmission Line speaker.  Both were audio high marks for me, leaving deep impression.  Looking back on it, the IMF transmission line may have offered considerable mode damping effect.  A few years later, Allen Perkins' (Immedia) short-lived (possibly never in production) transmission line/ribbon speaker also had a special quality of bass linearity.     

JICRO

  • Jr. Member
  • Posts: 16
Hi Jim,

Good to hear from you!  I always enjoy your patent reviews in Voice Coil.  Thanks for posting this information, I was not aware of it, and for your offer to make a copy available to people. 

If anyone would like, here's a direct link to the patent application on the USPTO site:

http://www.google.com/patents/US20140060959

Hello Duke,

Thank you for your kind words...It is good to know that you enjoy the patent reviews.

I came back to make a short reply for now, and see that the discussion is off and running.

I must say that I can relate to MJK's response to the presentation of the MVW system.

It is unfortunate that the inventors choose to use language that obfuscates the understanding of the functionality of the enclosure topology.  If they truly wish to have others in the field of loudspeakers/acoustics understand and support their concept, then it would be much more effective if they either created a definition of terms, or drew linkages between their terminology and concepts that are more commonly referenced in the field.

In looking back over nearly a hundred years of loudspeaker history, I have yet to see any advancement that could not be reduced to simple terms and analogies to allow better understanding.

While I will attempt to keep an open mind, historically, I have found the use of terms that are new, exotic, or from another field or narrow aspect the field being discussed, the out come usually exposes one of a few things, such as;

   A marketing device, meant to impress the naive and befuddle the well informed, or, reference to criteria that do create real effects, but those effects are so small, or out of band, as to be audibly insignificant.

I have a number of comments about the design concept, which I will try to get around to posting after today.

For now, I must say that after a first pass read of the patent, one is immediately disappointed in the lack of useful disclosure.

The patent system was originally set up with the basic premise that the government will offer a substantial monopoly on an invention for 17 years from the grant date (now, since 1995, 20 years from the filing date) in exchange for the inventor teaching the public enough reduction to practice information that one skilled in the art would be able to build a ‘best mode’ version of the invention.

In the patent there are no specifications, dimensions, references to T/S parameters and their relationship to the architecture, no relational dimensions of the different chamber sections, nothing whatsoever that would teach one how to create a reasonably functioning unit, let alone an optimized device.   

Also, there are no measurements disclosed and no comparative benchmarks illustrated.

This combined with the manner in which the system has been discussed by the practitioners and fans, does nothing to minimize one’s skepticism.

I realize that a good demonstration has been achieved, and those that heard it were impressed, but anyone experienced in the industry knows that the number of external variables involved in show demonstrations is enormous.

That said, I will keep an open mind and pursue further analysis.  Frankly, the main reason for doing so is based on my respect for your (Duke’s) understanding of which parameters impact loudspeaker sound quality and the assumption that he has studied the concept adequately to have uncovered some achievement that cannot be duplicated, or approached, with prior art technology.

At least, it is always entertaining to have a new item that generates excitement by tapping into that part of us that wants to believe there is something that can come along and transcend anything we have experienced before.

It could happen…

All the best,

- Jim

genjamon

Jim! Classy post! Much appreciated  :thumb:

I'm not technically literate in loudspeaker design, but interested in these designs and hoping the dialogue remains productive among those of you with expertise.  :)

DS-21

  • Full Member
  • Posts: 332
Anyway I don't blame you one bit for being skeptical; if I were in your position, I would be to the extreme.  The most I could ask of you or any other skeptic would be to not indulge in contempt before investigation.

Duke, have you, James, or  the inventors taken any ground-plane measurements of these devices?

FR would show whatever bass extension differences exist between this cabinet and "conventional ones," and sweep at various levels would show as the claimed dynamic expansion at higher SPLs. The best way to quell skepticism is data, especially now that the invention has legal protection. I for one would love the device to do what's claimed. You seem to chase what actually matters in loudspeaker design, and in the past your public posts have led me to discover some great loudspeakers, such as the Gradient Revolution. But at this point it's hard to call the assertions as to performance of the MVW "claims," because (at least I haven't seen) any data to support them.

If I'm wrong about the absence of public data, I apologize and ask you to point me towards it. Because I've looked and haven't found it.

Leland Crooks

  • Jr. Member
  • Posts: 10
Not my place to answer for Duke, but I do feel compelled to respond to just one item asked for in the patent by Jim.  I don't know why it jumps out at me from all the other pertinent questions, but it does.  I do have more experience in running multiple transducers in this design. 

T/S parameters have very a small impact on the loudspeaker cabinet.   They're incredibly flexible as to driver choice.  I can take a dual 8" PA system top, drop 2 8" subwoofer transducers into it and it will perform admirably, better than a sealed or ported box.  That's true of all of the dual driver designs, and to a great degree of all the of single driver subwoofer versions.  The only T/S parameter we've defined as very important is F/S.  It needs to be minimum 80hz, 60-70 is optimum,  for a limited high range cabinet like a PA top.  As low as possible if a full range loudspeaker is desired.  For subwoofers the lower the better, depending on the application and sensitivity in the passband required.  QTS between .4 and .5 seem to be best also, but we've found many exceptions to that.     Those are the two starting points we use when selecting appropriate transducers. 

Duke

Thanks for your thoughtful and professional post, Jim.  I apologize for this reply being slow; my internet connection has either been timing out or non-existent. 

My understanding is that the modern patent law protects the first to file, not the first to invent, assuming the patent is granted, so there is pressure to get something filed quickly.   If it were me, this would be among my concerns:  If the patent isn't granted and you've disclosed all of your trade secrets in the application, you've just given all of your intellectual property away for nothing in return.  The inventors have told me that their wording is deliberate, that they have followed the advice of their patent attorney, and that their intention is not to mislead customers, but rather to avoid assisting competitors who would rather be given the fruit of their labors for free instead of licensing it.   

They play things close to their vest.  It has only been since my last post here that I learned they do in fact have and use math models and a computer model.  Again, this is not something they are inclined to give away.

For now, I must say that after a first pass read of the patent, one is immediately disappointed in the lack of useful disclosure.

The patent system was originally set up with the basic premise that the government will offer a substantial monopoly on an invention for 17 years from the grant date (now, since 1995, 20 years from the filing date) in exchange for the inventor teaching the public enough reduction to practice information that one skilled in the art would be able to build a ‘best mode’ version of the invention.

In the patent there are no specifications, dimensions, references to T/S parameters and their relationship to the architecture, no relational dimensions of the different chamber sections, nothing whatsoever that would teach one how to create a reasonably functioning unit, let alone an optimized device.   

Also, there are no measurements disclosed and no comparative benchmarks illustrated.

This combined with the manner in which the system has been discussed by the practitioners and fans, does nothing to minimize one’s skepticism.

As I understand it, the intent of the inventors is to patent their basic alignment, rather than a specific loudspeaker design, and the figures are the starting points for the different embodiments of their alignment.   Using those figures as guides, a person could build a working model.  It would not be optimized, but it would be functional.   

Big E has their own forum, and if you register, they have a section entitled "Big E BS".   In their words:  "Want to call out the Big E inventors and/or manufacturers. Do it here. We welcome skeptics...just keep it clean and professional."

That said, I will keep an open mind and pursue further analysis.  Frankly, the main reason for doing so is based on my respect for your (Duke’s) understanding of which parameters impact loudspeaker sound quality and the assumption that he has studied the concept adequately to have uncovered some achievement that cannot be duplicated, or approached, with prior art technology.

At least, it is always entertaining to have a new item that generates excitement by tapping into that part of us that wants to believe there is something that can come along and transcend anything we have experienced before.

It could happen...

THANK YOU FOR HAVING AN OPEN MIND!!

I think everyone involved with this (myself included) have had to ask themselves whether they are self-deceived.   

A pivotal point early on for me was watching a youtube video, listening through headphones.  In the video, a camera with attached high-quality microphone is moved around a gymnasium while a singer rehearses for a play, singing through the PA system.  I was surprised by the consistency as the camera/microphone is moved around; it was beyond what I would have expected from a good quality conventional PA system.  Listen to the song all the way through and pay attention to where the camera (with attached microphone) is in relation to the PA speakers, as the distance changes quite a bit, and remember this is in a high school gym, which is about as bad an environment for clarity and intelligibility as you can get.  This is the direct unprocessed feed from the microphone. 

I don't know whether that video clip will impresses anyone besides me, but after hearing it, I decided it was time to play my "if you can't beat 'em, join 'em" card, because I don't think I could beat the consistency-throughout-the-venue that that system demonstrated.  Granted the venues my home audio speakers are used in are a lot smaller, but still, to my ears that video demonstrates something done well that I wanted a piece of.

Duke

Here are some links to fluid dynamics modeling programs which could be used to analyze what is happening in the loudspeaker.
Open source freeware
http://www.openfoam.com/

http://www.macworld.com/article/1024399/tetruss.html
"TetrUSS is used in aerodynamics and fluid dynamics analysis, and has been used on major projects including High Speed Research / High Speed Civil Transport, Hyper-X, Abrupt Wing Stall, Mars Scout, Joint Strike Fighter and more. What's more, the software has been used in the civilian aerospace industry, academy, automotive, biomedical and civil engineering fields.

NASA research scientists and the Air Force Research Laboratory developed TetrUSS for their own use, and it has evolved into an unstructured-grid flow analysis and design Computation Fluid Dynamic (CFD) software system. It's available free of charge to U.S. entities, citizens and permanent residents. A free training course is even available at NASA Langley Research Center, as well."

Also fluid dynamics for your iPad
http://www.algorizk.com/
Navier Stokes equations
https://itunes.apple.com/nl/app/fluid-dynamics/id382274493?mt=8

Thank you very much, Scotty!  Steve Regier (one of the inventors) told me that he was unaware of these, and appreciates your taking the time to find and pass them along.   

Duke, have you, James, or  the inventors taken any ground-plane measurements of these devices?

FR would show whatever bass extension differences exist between this cabinet and "conventional ones," and sweep at various levels would show as the claimed dynamic expansion at higher SPLs. The best way to quell skepticism is data, especially now that the invention has legal protection. I for one would love the device to do what's claimed. You seem to chase what actually matters in loudspeaker design, and in the past your public posts have led me to discover some great loudspeakers, such as the Gradient Revolution. But at this point it's hard to call the assertions as to performance of the MVW "claims," because (at least I haven't seen) any data to support them.

If I'm wrong about the absence of public data, I apologize and ask you to point me towards it. Because I've looked and haven't found it.

I haven't done any ground-plane measurements or outdoor measurements, just on-a-stand measurements in my lab, some time-gated and others not, depending on what I'm looking for.  For then non-gated measurements, I compare them with measurements of known quantity speakers taken with the same speaker and microphone locations. 

This was posted on TalkBass some time ago: 


The red curve is one of my bass cabs, and the blue curve is a Big E bass cab.  I recognize the dips and peaks in my cab's curve well enough to conclude that the data is good.  This doesn't prove anything of course, but imo that Big E curve is darn good for a bass cab.   

My cab uses a single 15" woofer whose parameters predict -3 dB in the upper 50's in the size box I'm using.  My woofer is roughly a cross between the Eminence Kappalite 3015 and 3015LF woofers, and then the Big E cab uses eight of these little 5" woofers: 

http://www.faitalpro.com/products/files/5FE120/8/5FE120_datasheet_8.pdf

There will be more data in the future, addressing the points you bring up. 

James Romeyn

  • Industry Participant
  • Posts: 3294
  • James Romeyn Music and Audio, LLC
    • James Romeyn Music and Audio, LLC
...The patent system was originally set up with the basic premise that the government will offer a substantial monopoly on an invention for 17 years from the grant date (now, since 1995, 20 years from the filing date) in exchange for the inventor teaching the public enough reduction to practice information that one skilled in the art would be able to build a ‘best mode’ version of the invention...

USPTO granted a friend of mine full patent for waveguide used for planar loudspeaker drivers.  I can't remember the exact costs associated with the process, but the total was in the neighborhood of $10k or $15k USD.  The first half of the cost goes toward the original application itself, the second half goes toward defending the request against persons who spend their life searching out and contesting every application request.  They contest and contest until they are convinced there is no further hope in contesting the patent, and the person requesting the patent intends to fight to the end.  In this case the "end" comprises the person requesting the patent spending about $5k to $7500 defending their original application.  Other independent professionals confirmed this scenario. 

Possessing full Patent after it is granted does not, by itself, protect IP.  If/when someone cheats and steals the protected IP for profit, the Patent holder must first find out, then decide whether to ignore it or sue the individual/industry committing the violation.  Patent attorneys cost about as much as any other attorney, maybe more.  At the end of the day, the IP holder is unlikely to recover the fees associated with the required legal action.  If the violators are overseas, forget it.   


Quote
I realize that a good demonstration has been achieved, and those that heard it were impressed, but anyone experienced in the industry knows that the number of external variables involved in show demonstrations is enormous.

That said, I will keep an open mind and pursue further analysis.  Frankly, the main reason for doing so is based on my respect for your (Duke’s) understanding of which parameters impact loudspeaker sound quality and the assumption that he has studied the concept adequately to have uncovered some achievement that cannot be duplicated, or approached, with prior art technology.

At least, it is always entertaining to have a new item that generates excitement by tapping into that part of us that wants to believe there is something that can come along and transcend anything we have experienced before.

It could happen…

All the best,

- Jim

I very much appreciate your professional input and attitude and look forward to your future comments on MVW cabinet loading.


Duke,
I humbly suggest you mention respective cabinet weights/volumes/dimensions: your TC15 reflex cabinet and MA85 (MVW 8x 5").  Also, just to confirm: all else being equal, at 1k Hz, actual MA85 output is about 2.5dB < TC15?     
« Last Edit: 28 Mar 2014, 11:21 pm by James Romeyn »

JICRO

  • Jr. Member
  • Posts: 16
Jim! Classy post! Much appreciated  :thumb:

I'm not technically literate in loudspeaker design, but interested in these designs and hoping the dialogue remains productive among those of you with expertise.  :)

Thank you for the nice reception. 
Hopefully there will be the opportunity to come to a full understanding of the MVW concept and how it relates to the prior art, and if that is the case, I'm sure this will be one of the primary locations to be able to read all about it.
Cheers,
- Jim

JICRO

  • Jr. Member
  • Posts: 16
Not my place to answer for Duke, but I do feel compelled to respond to just one item asked for in the patent by Jim.  I don't know why it jumps out at me from all the other pertinent questions, but it does.  I do have more experience in running multiple transducers in this design. 

T/S parameters have very a small impact on the loudspeaker cabinet.   They're incredibly flexible as to driver choice.  I can take a dual 8" PA system top, drop 2 8" subwoofer transducers into it and it will perform admirably, better than a sealed or ported box.  That's true of all of the dual driver designs, and to a great degree of all the of single driver subwoofer versions.  The only T/S parameter we've defined as very important is F/S.  It needs to be minimum 80hz, 60-70 is optimum,  for a limited high range cabinet like a PA top.  As low as possible if a full range loudspeaker is desired.  For subwoofers the lower the better, depending on the application and sensitivity in the passband required.  QTS between .4 and .5 seem to be best also, but we've found many exceptions to that.     Those are the two starting points we use when selecting appropriate transducers.


Hello Leland,

I would not be so bold as to argue with someone that is actually building and testing these devices, when I have not yet had any direct experience with an MVW loudspeaker.  But, I would say that optimized T/S parameters almost always provides an opportunity to maximize performance over random, or wide ranging T/S parameters.  Historically, there has always been an optimal T/S combination and relationship that will optimize performance to a theoretical maximum capability relative to efficiency/bandwidth/enclosure volume for a given system architecture.

One aspect that can fool one into thinking that a system is relatively impervious to T/S parameter variations, is that one can often find that a system can utilize a wide range of Qt values, but this is usually only the case if one also alters Vas and Fs in a compensating manner.  If one follows this formulation in an optimal fashion, one can create a table that appears to have widely varying T/S parameters, but in actuality, it is a very specific T/S parameter 'balance' that is important for maximizing performance.

One excellent example of this is expressed in Keele's AES paper "A New Set of Sixth-Order Vented-Box Loudspeaker System Alignments" presented in 1974 AES 49th Convention and in the June 1975, Vol. 23 No. 5, wherein Qt values were altered from 0.150 to 0.598, while maintaining the same performance, by way of maintaining precisely corresponding variations in Fs and Vas.

This may be an effect you are observing with the MVW systems.

If it is the first system ever to be independent of T/S parameters, that will make for a very interesting study in itself.

All the best,

- Jim

JICRO

  • Jr. Member
  • Posts: 16
Thanks for your thoughtful and professional post, Jim.  I apologize for this reply being slow; my internet connection has either been timing out or non-existent. 

My understanding is that the modern patent law protects the first to file, not the first to invent, assuming the patent is granted, so there is pressure to get something filed quickly.   If it were me, this would be among my concerns:  If the patent isn't granted and you've disclosed all of your trade secrets in the application, you've just given all of your intellectual property away for nothing in return.  The inventors have told me that their wording is deliberate, that they have followed the advice of their patent attorney, and that their intention is not to mislead customers, but rather to avoid assisting competitors who would rather be given the fruit of their labors for free instead of licensing it.   

They play things close to their vest.  It has only been since my last post here that I learned they do in fact have and use math models and a computer model.  Again, this is not something they are inclined to give away.

As I understand it, the intent of the inventors is to patent their basic alignment, rather than a specific loudspeaker design, and the figures are the starting points for the different embodiments of their alignment.   Using those figures as guides, a person could build a working model.  It would not be optimized, but it would be functional.   

Hey Duke,

I won't put everyone to sleep with an extensive discussion of patent law and strategy, but there are just a couple points;

I must admit, my first concern was that my BS detector went off when reading the patent and finding it using similar language and presentation that I had seen on this site and the BigE site.  Usually, even if one wishes to use a marketing-smoke-screen to impress, and/or maintain secrecy, the patent application usually provides a more serious and thorough disclosure of a new invention, assuming there is actually something of value to disclose. 

In this case the patent was essentially a mirror of what has been mentioned to date in the forums.

So, if I were to assume that what is being disclosed is new and valid, I would shift my commentary on the patent to be that I believe the inventors may be putting themselves at risk of their patent being invalid, in that the requirements are such that one must teach their "best mode" version of an invention.  One can't teach substandard versions and attempt to keep the best versions as a trade secret and still expect to have a robust patent if challenged in court.

Relative to one of your comments, it would seem to me that they would have very little risk of not getting their patent granted if their invention is as novel as suggested by the inventors.

That said, they and their patent council have determined a strategy that they believe is the best approach, so I can only wish them well, with the result, hopefully, being that of an effective patent application and successful business.

Cheers,

- Jim

JICRO

  • Jr. Member
  • Posts: 16
USPTO granted a friend of mine full patent for waveguide used for planar loudspeaker drivers.  I can't remember the exact costs associated with the process, but the total was in the neighborhood of $10k or $15k USD.  The first half of the cost goes toward the original application itself, the second half goes toward defending the request against persons who spend their life searching out and contesting every application request.  They contest and contest until they are convinced there is no further hope in contesting the patent, and the person requesting the patent intends to fight to the end.  In this case the "end" comprises the person requesting the patent spending about $5k to $7500 defending their original application.  Other independent professionals confirmed this scenario. 

Possessing full Patent after it is granted still does nothing to protect one's invention.  If/when someone cheats and steals the protected IP for profit, the Patent holder must first find out, then decide whether to ignore it or sue the individual/industry committing the violation.  Patent attorneys cost about as much as any other attorney, maybe more.  At the end of the day, the IP holder is unlikely to recover the fees associated with the required legal action.  If the violators are overseas, forget it.   


I very much appreciate your professional input and attitude and look forward to your future comments on MVW cabinet loading.


Hi James,

I agree that the nature of our legal system is such that it is difficult for the small entity to justify the cost of patent prosecution and defense.  I often find that individuals and small audio companies file patents to be able to use the USPTO as a marketing validation of their invention, and they ultimately have no intention of every challenging any infringers, which can reach cost levels that are easily ten times that of the cost of the patent itself, even if they prevail in the court battle.

Unfortunately, patents tend to offer the best protection to those companies that are so large, and with such deep pockets, that most competitors would be too afraid to ever risk infringement.  The small guy seldom has the ability to scare-off infringers to any great degree.  It used to be that large companies were concerned about negative PR if seen beating up a small company, and the courts favored the small guy to a degree that the large corporations would think twice before challenging a small inventor, but that does not seem to be the case these days.

That said, I've also found that some large, deep pocket organizations are afraid of taking infringement risks, even against a little business, because there are many "ambulance chaser" attorneys that will take up the cause for a little guy to go after a big deep pocket settlement if they can keep 50% of the 'winnings'.

So, it's a gamble from either direction.  If an individual has a significant invention, I usually recommend getting a patent, and then licensing or partnering with a large organization, such that any company that might consider infringing your patent will see the 800 pound gorilla standing at your side, ready to support your defense. It tends to be a good approach to both earning a good income from the invention and provides an effective deterrent to infringers.

In terms of further analysis of the MVW, I will be glad to share my findings as I continue to explore the rather interesting design. 

I have explored the structure and have found the apparent changes in cross sectional area, vs. position along the length of the waveguide, consistent with other work that we have done to smooth the response in wide-band, multi-resonant quarter wave systems and transmission lines, without using any damping materials. 

Much of the effort is to smooth the pass band, while avoiding any sacrifice in efficiency, and effective minimization of diaphragm excursion, at the system low-end cut-off frequency.

I must mention that I am at a loss as to understanding how the system would act as a dynamic range expander, as has been suggested.  I also question whether that is something to strive for, as it implies a non-linearity in the system, which is not a desirable attribute if one is aiming to create a neutral device.

But, as with all the observers that are attempting to opine from the bleachers, I may very well have a significant gap in my knowledge about the actual structural and functional elements that are incorporated in an MVW system.

Best regards,

- Jim


James Romeyn

  • Industry Participant
  • Posts: 3294
  • James Romeyn Music and Audio, LLC
    • James Romeyn Music and Audio, LLC
Jim,
I'd be indebted for your comment on the following.  Maybe 15 years ago Bob Carver (yes, that BC) told me that listening tests support the conclusion that human hearing sensitivity to THD in the bass range is so low that humans perceive little if any difference between 1% and 30% THD. 

I posted the above many times and shockingly, no one ever contradicted it.  (Conversely, I presume there is similar agreement that human sensitivity is extremely high to mid range phase and THD.  John Krutke of Zaph Audio posted that humans have little sensitivity to large FR aberrations in the top most octave, IIRC, windows as large as 6 dB.)

Back to bass THD: What's critical about Carver's point is that any money spent reducing THD below the threshold of audibility is wasted.  IOW, THD spec below the threshold of audibility is, in effect, nothing more than window dressing.  I don't know how true or false is Carver's statement, but my experience indicates a resounding yes.

A friend of mine used to build 400+# floor to ceiling line source subs with four or six active 12s.  Over the years I heard several similar sub systems, including IRS III in dedicated sound room.  Every time I heard them I was impressed.  I became convinced their most attractive quality was exceedingly low THD, you know, woofers barely moving except for canon shots, etc.  Now, with further experience of other sub systems with higher THD but natural mode damping features, I'm convinced the most audible feature of the line source subs was their natural mode damping for one of the most audible modes, being floor to ceiling bounce.       

I think the only spec I've ever seen re. modal effects is FR graph or simple numeric dB.  Considering that modal effects are 100% synthetic bass notes generated by distinct numeric relationships (listener or mic location, boundaries, speaker locations) I have always thought that modes expressed as THD can easily be well over 100%.  Please LOL at my guess and correct at will.

But the most critical defect about modes is their effect on timing.  I think of modal effect as a synthetic note only indirectly related to the original note in the music score, and this unrelated note continues playing over the next note appearing in the score. 

I suspect MVW has natural mode damping quality, and this may be among it's best, most audible, and most desirable features.