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Old 21st March 2007, 03:19 AM   #11
mamboni is offline mamboni  United States
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Thomas and Bud:

I'm reading your discssion with great interest. By the way, I am a physician by trade and training and not as proficient as you guys in the technical and engineering aspects. I would most interested in what you guys come up wiht and hope you will post some photos.

Thomas hit on all the key features that determined selection of the 10" Pioneer woofer. The thing is, as you guys have noted, loudspeaker manufacturers experiment with all manner of exotic materials and coatings in an effort to eliminate boundary effects/cone resonance. But, the technique we are using here requires no exotic materials, just a modicum of engineering and design. And in the bargain, one has converted an inexpensive woofer into one that can match or exceed the expensive exotics with the fancy composite cones and proprietary viscoelastic coatings. Now I do not have the setup to do detailed frequency reponse and waterfall plots, and I suspect Bud does; but, based on my hearing the felt-treated woofer sounds amazing clean and delicate, as if all manner of energy storage has been eliminated. But, one would need measurement of a treated woofer to prove this. If this is true, then these post-production mods might have a market, either as ready-use modified woofers or kits for the user to apply the treatment himself. Imagine the advantages: a woofer that is non-resonant and resistant to cone breakup would require no crossover, and would sound superior to almsot any "coventional" woofer. It could be a boon to hobbyists who want to build a phase and time correct loudspeaker and eliminate the crossover.
 
Old 21st March 2007, 05:22 AM   #12
BudP is offline BudP  United States
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Utopix,

Ummm.... acrylic floor wax.... industrial strength. I buy mine from Micro Scale Products, called Micro Gloss. The real deal is that it needs to exhibit transverse wave energy transfer at speeds faster than that of sound through air. Most varnishes and lacquers will not do this and you can clearly hear the difference, but I have never found a way to measure it.

The paint I use to letter the blocks onto a driver surface is made by Poly Scale corp. Flat Finish #404106. Both of these materials will be in any decent hobby shop that sells plastic models and some HO scale train items.

Mamboni,

I am delighted to see the interest you have stirred up. Have you thought about using your process on more conventional speakers? Still placed on the non free air emitting surface, I suspect that a considerable improvement in midrange driver clarity might result. We may be stuck with just the EnABL process for dome, cone and linnaeum style tweeters... though I have seen the odd Walsh based tweeter show up. Not a drawback. Certainly a conventional speaker setup, with your pattern on the back of woofer and cone midrange, my pattern on the front to lightly correct whats left over, and an EnABLE'd tweeter, will rival the Ohms for clarity, depth of field and sheer musical beauty. And that is saying something!

While it has taken some number of years to accomplish I have a conventional system that will easily outperform my original treated Ohm F's in all of the categories you would care to list, so I am sure your idea can be so applied and between us we may just get as close to perfection as humans in the real world can accomplish.

Bud

I am still very intrigued to try both processes together, I do sense a possibility of synergy.
 
Old 22nd March 2007, 03:51 AM   #13
BudP is offline BudP  United States
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Default Getting you some tools

Mamboni,

I have to reinstall Auto Cad 14, after that herculean task is accomplished I can plot a set of patterns based upon large end diameter, small end diameter, height of cone and thickness. This plot will be on a flat piece of paper that you can then roll up into a cone.

Many years ago I wrote a lisp program for taking this data and creating this flat drawing , with all blocks, and proper spacing from edges included.

If there is interest I will make the lisp program, which runs in Auto Cad 14 and possibly later versions, available for free. With that and a Corel file I can provide you can make cone templates that will show you where to put the blocks and scaleable Corel circular templates, to guide your placement of blocks for a given pattern. There are always two patterns for a cone surface and the smaller pattern can be merged with one that will be applied to a center dome for a three row pattern with the first and third rows on the dome and cone respectively and the middle row in the joint between.

This process will take a day or so to get up and running again and I will then ask you for dimensions for a cone that interests you, though I may not be able to plot the file, as I no longer have a large format plotter. I am sure you can find someone to help you with this. The Corel file does require Corel 6 or newer to allow you to open and scale the circles of blocks to a useful size, but, again this should not be hard to obtain as most printing companies can print from both Corel files and Auto Cad DWG files.

Bud
 
Old 22nd March 2007, 06:52 AM   #14
BudP is offline BudP  United States
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Mamboni and all,

Here is a sample cone you can cut out and make into a cone, either an innie or an outie. As you can see the block size in a ring set changes with the actual diameter that it must cover. The lisp program that I have performs all of these calculations and draws the resultant conic section as a flat surface. I have converted it ot a jpeg format for your convenience

The specifications need to be for:

The large cone opening diameter, or the diameter just at the lowest edge of the surround where it overlaps the cone.

The small cone opening diameter, or where the center dome actually touches the cone surface.

The material thickness, a guess will do.

The length down the cone surface from the surround lower edge to the top edge of dome attachment, on the cone.

Obviously these dimension call out specs are aimed at the normal face of a cone speaker, but I am sure all of you can see how to use the dimension call outs for the backside or Walsh side of the cone.

Dr. Mamboni, when you have a set of dimensions you want to experiment with, and I would strongly suggest a small diameter cone, like a 6.5", so we can keep the conic lay out sheet on a letter size piece of paper, I can provide another of these, close to correctly sized and the Corel block rings that you would use as a location template, to actually letter the blocks in place on the cone surface.

This is not as complicated as it sounds here. The teenagers I have taught this to take about 30 minutes to completely treat a cone, on both sides, with blocks and conformal coat.

Bud
 
Old 23rd March 2007, 03:24 AM   #15
BudP is offline BudP  United States
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Hi Mamboni.

I did not really intend that one as a stencil, cutting all of those squares would take at least three times longer than just drawing, or "lettering" the blocks in place using the traditional method with a calligraphy pen and a circular chart of block placement, based upon the diameter and size found in the type of "stencil" you have now seen.

Thomas and I are converging on a method for stencil making with either etched block pattern circular strips, that wrap half way around the cone for one set of block rows, with a 3M tack adhesive on the back and a sponge to dab the openings with, or a laser cut vellum stencil, with the same tack adhesive and 1/2 cone circumference strip scheme.

I am proposing just what you portray, EnABL on the outside and Mamboni on the inside, just how and where you place it now. I do not think that a heavy application of EnABL control will be needed at all. You will almost certainly see benefits in extended high frequency range, roll off smoothness and quite possibly a 3 dB increase in overall efficiency, though that is never a given, unless you do not want it to happen.

I have attached a sample flat block guide that would be used to guide placement of the blocks with a lettering pen.
 
Old 23rd March 2007, 05:05 AM   #16
Utopix is offline Utopix  Canada
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BudP

May I make a suggestion for the stencil for large diameter woofer(like the 10" woofer that mamboni already made). You can print on a single sheet of paper only a small portion of the stencil, not the complete cone. (See attached picture).

As you can see, we this new stencil we only have to paint the blocks from 1 to 10(big blocks and small blocks) on the woofer cone, after that we just move the stencil to the right and align the 1-2 holes of the stencil on top of the already paint block number 9-10 (for alignement). And we move on until the entire woofer cone is done. Unless the block alignement must be precise within a 1/100 th on an inch, I think that this method is valid.

With that in mind, it is easy to imagine that you can generate (with your program) on a single sheet of paper many different template for different woofer.

Just a thought!
 
Old 23rd March 2007, 07:43 AM   #17
BudP is offline BudP  United States
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Utopix,

Quite an excellent thought. Are you ready to give it a try?

Using your method we can make a flat pattern that sits just below where you will letter the pattern. A good convention is that the blocks closest to the cone describe the blocks right next to them and then you use the lower blocks already on the cone to describe the length of the whole upper block set and just get as close as you can for the correct space between the upper blocks. I usually do two lower blocks and then the upper between them so I am able to clearly see the pattern I am creating. This will be good enough, I assure you.

We might still want to have the upper, or smaller diameter pattern be a full circumference, with perhaps a single slit so you can get it on to the cone and then tape it back together and let it settle.

Just as with Mamboni's treatment there is a lot of forgiveness for small errors.

If you have access to a copy of Corel 6 or newer, and I am certain it is available on eBay, I can post the latest flat twin ring file and you can size it to fit your needs exactly and print out a full sheet with as much of the diameter of the cone you want to work with, or as much as the letter size paper will hold. I do believe you have found the key, thank you.

Bud
 
Old 23rd March 2007, 03:17 PM   #18
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Has anyone thought of looking at the ripple pattern produced by the Enable array when used at the far end of a shallow water ripple tank? Remember these simple analog/mechanical devices used before computers?

Although the claim of performance is not in question here at all I think it would be interesting to see the way it works. While at it a triangular edge could be tested as well.
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Old 23rd March 2007, 05:46 PM   #19
BudP is offline BudP  United States
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Utopix,

Sorry, I was so tired last night that I did not notice how far I had strayed from your idea, until this morning, when I awoke from a dream about being lectured for short sightedness.

The one piece panel that you are talking about will work. I suspect it needs to be made from vinyl and might best be made with a sign makers vinyl cutting machine. although I have never even seen one of these to know if it will cut rectangles in the middle of a space, rather than have it slice to the spot and then cut the rectangle.

I am willing to provide a specific pattern size for you to experiment with. Because of the number of times that you will have to peel and reattach you may need more than one application of the 3M tack adhesive Thomas was talking about.

Again I apologize for stomping all over your idea last night, I will probably do it again though.

Bud
 
Old 23rd March 2007, 06:33 PM   #20
BudP is offline BudP  United States
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rcavictim,

I did perform an ad hoc wave tank test many years ago, and made simple line drawings of the results. If you would like to analyze them I will dig them up and put them into a pdf for you to look at. I will caution you that the effect they portray caused my high energy physicist friend who witnessed them, to claim they were the same as magic... something happening in front of his eyes that he not only did not understand but could not believe he was seeing.

A short description is a set of blocks, meaning two from one ring and a center set from the adjacent ring were cut from two pieces of 3/8" thick wood, as fingers sticking out from the edge about 1/2 inch. In other words every thing but the fingers was cut away and the resultant blocks followed the pattern array dimensions shown in the patent.

These block holders were sized to fit stiffly between the narrow walls of a 8 inch by 4 foot fish tank, half filled with water, about 6 inches deep Fluorescent lights were positioned underneath, lengthwise, and a piece of white cardboard was hung a couple of feet above the tank, to show the shadows of any wave action in the tank. A 6 inch wide dipping paddle was used to agitate the water at one end of the tank and the pattern holders were positioned six inches away from the dipping end of the tank, with the fingers into the water about a quarter of an inch. I make no claims about scientific rigor being used here, I just wanted some idea of what the heck was going on!

When the dipper was agitated, mostly up and down, without the pattern blocks pushed down into the water the expected choppy surface with waves that eventually became quite chaotic in direction arose after a few moments of agitation and took a few tens of seconds to completely dissipate and allow the water to become calm again.

When the pattern was shoved into the water that quarter inch and the dipper agitation restarted, a checkerboard pattern arose between the pattern and the dipper and from the other side, seemingly in perfect sync with each of the dipper strokes, a smooth, straight line of wave appeared from the pattern edge shadow, flowed to the end of the tank and dissipated without any obvious reflections. This pattern of activity held until you stopped dipping and the last wave occurred with the last dipper stroke and the water surface quickly became calm again.

All of this was clearly shown on the white cardboard surface as shadows. There was a pretty wide range of dipping cycle speeds that provided this effect, as the dipping was done by hand. I did not explore the out of range effects at the time so I cannot report on the failure modes.

Round pattern dots work fine, down to about 4 kHz and out to beyond my ability to measure. Below this vague cut off point the square edged shape begins to become necessary, though these "square" edged blocks usually are not all that square edged, but definitely not round either. I am quite certain, through some experimentation, that many "shapes" will work, some better than others at certain frequency ranges on certain materials, other than paper.

The rectangular in spirit blocks seem to work across the frequency band though at this late date I no longer try to make rectangular shapes on small high frequency drivers. Round dots, thankfully, work here very well. In fact I just treated a set of Pioneer piezio electric film tweeter to use to top off the high frequencies from the Radio Shack Linnaeum, baby cheek, soft horn wall tweeters I use. These only provide signal out to 13 kHz and the Pioneer half round "can" shaped devices are on a 0.22 mfd induced slope to match and extend out to 30 kHz or so..

Bud
 

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