[Russell Dawkins]

By the way, that formula that Ribbonspeakers.net alludes to has interested me over the years, but I never had the chance to experiment with it.

Apparently it came out of Bell Labs. The formula is simple: LF roll off times HF roll off should equal 400,000 to sound balanced. For example if your LF -6dB point is 40Hz, your HF -6dB point should be 10,000Hz, according to this formula. So 20Hz - 20kHz works, as does 80Hz - 5kHz.

This explains why telephones sound fairly natural in tonal balance with a 200Hz - 2KHz range.

In Hi Fi News around 1975 they published a "variable window" circuit with which you could continuously vary the width of the window while maintaining the 400,000 rule.

I wonder if, with my new super tweeters flat to 100,000Hz, I now have to find a way to extend my LF to 4Hz.

[James Romeyn]

Not much audio at those two extremes, production-wise, reproduction-wise, or perception-wise......as a matter of fact, none!

[dcloomer]

I'm still attached to my old (it's all relative) Tower IIR's:  I assembled them myself and ate spam and cereal for two months to afford them while in college.  Are these "Wave Guidable?"  Is it even an appropriate use of the technology?  Will Brian trade them in on some new RM40's that are just in his way?

[James Romeyn]

I'm still attached to my old (it's all relative) Tower IIR's:  I assembled them myself and ate spam and cereal for two months to afford them while in college.  Are these "Wave Guidable?"  Is it even an appropriate use of the technology?  Will Brian trade them in on some new RM40's that are just in his way?

Brian's particular waveguide technology is aimed specifically at the ribbon products, for a long list of reasons.  I can't speak for him, but would take an even bet he's not going to offer it for your model or any non-current model.  It is, IMO, impossible for it to be adapted to the TII's that have the mid/treble array in a horizontal arc.  The technology requires all drivers above the bass range to be in a straight vertical alignment.  For instance, none of old SRE towers with the tweeter in the bass tower & the ribbon mid beside, can be adapted.  (BTW, the arc is the only known difference that appears to make the old TII sound better to me than the later SE models having all drivers vertically aligned; either that or xo differences).  I've heard several of both models in many different venues.

[Butterfly]

Hello everybody,

It is exiting to read about the new baffle BC claims to have invented. However, he has not.

Year 2005 we received the patent of a new technology to implement ribbon speakers. The priority date of the patent is Jan 2004.

The constant width baffle is a part of this design. This is correct that it works excellent and many of its benefits has been described.
 
Today, the patent can be downloaded from the European Patent Office Database.
Here is the link: http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO2005074318&F=0

Year 2006 the patent will also cover North America.

You can see speakers with the constant width baffle made of diamond glass (equal to crystal glass) on my company website.

BTW: It is possible for other manufacturers to license the new technology, which has been named Q-ART.

[JohnR]

Great. Thanks Peter.

[woodsyi]

Having taken a cursory look and I am not a patent lawyer, there seems to be a wiggle room for both of these to be patented.  Peter's system costing $25k seems to generate CD by ACTIVELY guiding the sound wave by means of an integrated transducer/waveguide.  Brians' system costing $650 as an easily implemented add-on to an existing speaker generates CD by PASSIVELY guiding the sound wave through a slot.  It will be interesting to see how this all plays out but I am glad I have one.  By the way Peter, your 1001s are doing great in my system.

[CornellAlum]

I looked at the pictures on the site as well.  They look nothing alike at all.  Just visualy speaking of course.

[ctviggen]

Under US patent law, there's an "all element" rule, meaning that all elements of a claim are necessary for infringement.  Claim 1 of the Thomson patent reads as follows:

"An acoustic transducer comprising a frame holding at least one magnet for generation of a magnetic field, and a ribbon comprising a material that is attracted by the magnetic field and having at least one electrical conductor, and wherein the ribbon is attached to the magnets by means of the attraction of the ribbon by the magnetic field for generation of sound by interaction of the magnetic field and a current flowing through the at least one conductor" (emphasis added).  

I do not believe Brian's CDWG has a frame including a magnet for generation of a magnetic field.  Therefore (under this extremely cursory analysis), there would be no infringement by Brian's CD of Thomson's claim 1 and its dependent claims.  

Thompson also claims the following in claim 15:  "A ribbon for generation of sound waves comprising a material attracted by a magnetic field, and at least one electrical conductor".  As Brian's CDWG does not use a ribbon having a material attracted by a magnetic field, his CDWG does not appear to infringe this claim.  

Now, if the disclosure of Thomson's patent discloses something that could be construed as similar to Brian's CDWG design, then there could be a problem for Brian in terms of patentability (depending on what the Thomson patent discloses and what Brian's application claims).  However, based on the claims of the Thomson patent I've reviewed, there does not appear to be any infringement by Brian's CDWG of Thomson's claims.  Naturally, this was a cursory analysis and it would take additional analysis to be completely sure (particularly since I don't have a CDWG as of yet), but there does not seem to be an infringement problem.

[wshuff]

The real question is, why is Peter now going by the name Butterfly?

[csero]

Couldn't we just call this whole thing by it's name - diffraction slot with a damped chamber (bandpass) behind and forget about patents. AFAIK the obvious can not be patented.

[fredgarvin]

Ctviggen, nice post, thoughtful information is always refreshing. From what I have read thusfar, the new waveguide may be huge for VMPS. The one factor that I always felt needed improvement was the vertical dispersion and off-axis response. A planar phenonema that one has to factor in when purchasing such. Sonically the new models, with waveguide, will be hard to match.

[Butterfly]

Hello everybody and sorry for interrupting

I wish BC good luck and I appreciate new inventions. However, I really can't see any new invention here, I can only see known improvements. There is no new technology or invention.

I believe BC will be able to receive a design patent to his own speakers, due to this is extremely easy to obtain. But when we talk about a real patent, this is FAR more difficult and VERY expensive.

Regarding the design, this is a wave guide that should be on all good quality speakers. The main difference here is that this is a wave guide to ribbon speakers due to their very bad dispersion. Because the neo8 is a planar magnetic transducer it has no acoustic shorting itself, which all real ribbons have. When making a long hole in an extra baffle the speaker will now begin to have some of the advantages that a line source speaker is born with. However, no new invention here, and no new line source.

I know it works and should have been on the wmps many years ago, but there is no new groundbreaking invention.

Regarding the patent I posted a link to, claim 14 is having a baffle with a similar advantage. However, to the new ribbon technology, where there is no cluing, but the planar magnetic ribbons can be changed in a snap by the customer himself. The reason is the ribbons are magnetic itself.

I believe the wmps waveguide baffle to wmps ribbon speakers is excellent to marketing and it will improve the sound, but there is no new technology, it is only a different design.

[warnerwh]

Waveguides apparently go back to the 70's. This one appears to have a 180 degree dispersion.  Are there other waveguides that will do this?

[Butterfly]

The advantage of 180 degree dispersion comes with the change similar  to a line source, due to the narrow hole in the baffle, which must be approx. 50 times longer than the width of the cone/ribbon.
Now, the infinite numbers of points (of the source) will begin to radiate the sound in cylindrical waveforms. A flat baffle will close off acoustical shorting. Both a baffle- and a cabinet  design will use its baffle to repeat the circular dispersion from the driver itself. Now you begin to have 180 degree dispersion...

May be too technical, sorry, it is too late here, I have to stop posting for today.

[woodsyi]

Thanks Peter for your comment and wishing Brian well with his CDWG.  I thought for a moment that there might be an interesting verbal firework with Brian and Peter.   As for patents, I am not sure that every patent necessarilly has to be a NEW invention.  A friend, who is a patent examiner (USPTO) was telling me about all these application on hinges and nuts and bolts -- how many "original" way can a joint hinge?  I dont' think a patent has to reinvent the wheel: it just has to incorporate a new implementation of known things.  I don't know if Brian's CDWG is patentable or not based on my very limited knowledge in the history of acoustic speaker industry but his lawyer certainly thought so.  I will say that it has one element common with other great ideas in history.  Looking at it,  I am thinking it's quite a simple and elegant solution.  Why didn't somebody do this before?  

[ctviggen]

A patent has to be new and non-obvious under US law and have novelty (akin to "new") and inventive step (akin to "non-obviousness") in European law.  That means that a unique combination of elements that are old can be both new and non-obvious.  As for waveguides being old, one has to determine what those waveguides were used for, what function they served, and what the disclosure says about them.  A waveguide for microwave radiation may not be applicable to a waveguide for creating improved dispersion from a speaker.   I could go on for hours about the nuances of patent law.

[Brian Cheney]

The diffraction slot is just one part of the wave guide of my invention.  The others are a planar baffle and damping for both the slot and the underside of the planar portion.

I read Peter Thompson's web site and his approach is quite different.  

A benefit of my invention is that it makes all drivers in the array into a true line source with all its advantages.  No lobing, no line-source-to-point-source anomalies, 180 degree dispersion  full range.

Yes, the approach is novel and inventive, quite enough for a letters patent.  I have worked in the field and know what it takes to get a patent.

Anyone who heard the RM 30 CDWG at CES knows how well my invention works.  I doubt anyone will want a speaker that is not CD once they hear any of our new CDWG-equipped systems.

[CornellAlum]

How was the cdwg perceived overall at CES?  Did you win any more awards or anything like that?

D~

[zybar]

How was the cdwg perceived overall at CES?  Did you win any more awards or anything like that?

D~

I haven't seen any comments or pictures yet in all the usual places:

AA
Soundstage
Enjoythemusic
Hometheaterhifi

George