A little working miracle?

[moray james]

Came across this patent application US2004/0251079 A1 which is also backed up by a functioning company actually building product. This might be a more fruitfull design to look into (as opposed to the Holliman Infrabass). Here is a link to the company's site though you will not find much info there with respect to how or why the design works. They do however have a number of products with measurements. The working principal may be of interest if you can figure it out. I have only skimmed the patent application an it does look to be kind of interesting. I just thought that some here might find it of interest. Regards Moray James.
Patent Application http://aiw2.uspto.gov/.aiw?Docid=200...y=389ED53DA4F0

Company link http://www.tbisound.com/index.asp

[BAM]

Your link doesn't work. Can you just give us the application number so we can search for that?

[moray james]

nt.

[moray james]

United States Patent Application 20040251079
Kind Code A1
Plummer, Jan Princeton December 16, 2004

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CLOSED LOOP EMBEDDED AUDIO TRANSMISSION LINE TECHNOLOGY FOR LOUDSPEAKER ENCLOSURES AND SYSTEMS


Abstract
An acoustic impedance matching enclosure is provided having a driver loaded into a chamber buffering the throat/mouth of a closed loop transmission line. Transmission line consists of a termination member, outer and inner enclosure walls, high-density lining and throat/mouth area. Transmission line eliminates internal random standing waves while providing variable-frequency standing waves that through superposition of the waves compensates for mass-acceleration loss of the high-end of the driver output while damping the resonance of the driver. Alternative application of the acoustic impedance matching enclosure is that of compression loading the driver directly into the closed loop transmission line and using an acoustic low pass filter to translate the output into low frequencies only through a port. Both applications of the acoustic impedance matching enclosure are to insure that the drivers' diaphragm is clear of disruptive internal standing waves, properly loaded at all frequencies and not easily affected by room reflections.


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Inventors: Plummer, Jan Princeton; (Marietta, GA)
Correspondence Name and Address: JAN P. PLUMMER
341 ENGLAND PL NE.
MARIETTA
GA
30066
US


Serial No.: 709538
Series Code: 10
Filed: May 12, 2004

U.S. Current Class: 181/199; 181/156
U.S. Class at Publication: 181/199; 181/156
Intern'l Class: A47B 081/06

[djk]

http://www.freepatentsonline.com/20040251079.pdf

[moray james]

I forgot about these guys. They would seem to be the easiest way to down load the patent and drawings in one easy proceedure.
So I will assume that you had a look at this idea, do you have any thoughts or comments on it? I appreciate your ability to get to the heart of a design and so clearly explain its workings.
The internal sealed line must increase the radiation resistance that the driver sees over a wide band. This very much reminds me of the Eliptoflex (see attached) method of vent loading similar also to the JR reflex loading principal. I guess that the bends in the line generate turbulence which helps to increase the load of such a small line. How well this idea works is hard to say not having heard one but they exist and are being sold. The 6 moons review was of interest. I also see physical similarities to the S.A.F.E. loading method which had a series of vertically stacked plates with small spacing forming a kind of transmission line.
Any and all comments would be welcome. Regards Moray James.

[johninCR]

I like that Eliptoflex. I always wanted to try something like that after holding an 8" driver over the driver hole for a sealed 12" and hearing a lot of bass.

[moray james]

have a look at the two JR loaded designs in the Supra Vox download section. Wonder if this could be incorporated into an Oken style cabinet?

[just a guy]

I have both of the patents now and the one main difference is that the sealed "transmission line" is open ended in the older patent and closed at the end in the newer one. There are other differences too, but that is the most significant. The diagram in figure 6 of the newer patent, which is most likely to be the commercial subwoofer only model, (but in this case without the side length extensions) is almost identical to the older patent model; again, the difference being the open ended "tl" terminus on the older one.

The 6moons review is extremely positive, as far as I'm concerned, especially with regard to the subwoofer unit. The one they reviewed is the one designed from the old patent. You can see the open mouth along the edges in the bottom view picture of the unit. Unfortunately, the newer unit was not reviewed because of complications with the inventor's new and old affiliates. This leads me to question whether the new unit is actually an improvement over the older one or if the inventor just needed a new product for his new company. Either way, at least the old one (subwoofer module) got a great review.

Figure 6 could probably be used to copy the new commercial model, unfortunately there are no measurements and there are a lot of unknown factors - the volume of the resonant enclosure, which side of the baffle the driver is mounted on, driver parameters, exact dimensions of the "tl" section, thickness and density of the absorbtion material and the final output port length are all relatively unknown.

From the commercial model we know exterior dimensions, output port diameter (2 inches) and average sensitivity in the range of 87 db/1w/1m. By all indications this box goes incredibly low considering it's size and the driver in it, but not incredibly loud.

Overall, it might be fun to try to make a box based on the new commercial unit's measurements and the diagram in figure 6 of the new patent and then try auditioning drivers. But other than that, there is just not enough information. I would be wary to scale all measurements by cone size difference.

A stereo or quad set of these might do the trick very nicely, (and dirt cheap) possibly as a base for an OB baffle.

[johninCR]

Originally posted by just a guy
A stereo or quad set of these might do the trick very nicely, (and dirt cheap) possibly as a base for an OB baffle.

This is what goes at the bottom of my latest OB baffle, a 15's pushed up behind the holes still to be cut in the baffles pictured. I'd never give up OB bass.