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Old 19th March 2007, 05:48 AM   #61
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Quote:
Originally posted by rcavictim
I have not removed a driver from it`s cardboard tube cabinet yet to look at the underside of the cone.
Be very careful if you try. The last set i tried to dissassemble had the cardboard tube glued to the edge of the surround (where you would find the cardboard gasket on a normal woofer) and the surrounds were destroyed when i attempted separation.

dave
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Old 19th March 2007, 07:39 PM   #62
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Quote:
Originally posted by planet10


Be very careful if you try. The last set i tried to dissassemble had the cardboard tube glued to the edge of the surround (where you would find the cardboard gasket on a normal woofer) and the surrounds were destroyed when i attempted separation.

dave

Thanx for that potentially day saving advice Dave! I`d hate to damage these.
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Old 19th March 2007, 08:00 PM   #63
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Default Walsh termination

Just in case you folks would like to step outside of the normal mass loaded cone termination regimen, please read this.

http://www.positive-feedback.com/Iss...ndingwaves.htm

The entire process was developed on a pair of Ohm F's and turned them into point source radiators, in a spherical sense. Also eliminated the reflections from the materials joints.

Bud
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Old 19th March 2007, 09:55 PM   #64
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Hi Bud

Any idea on how the pattern was applied and what material was used? Conformal coating should not be a big problem but gluing on all of those little squares is really going to take some time!!

How in the world did they do it?

Could not find any other development of the concept - did / has anyone employed the design?

Interesting idea (the pattern) - but I think that mamboni has allowed for this with his design of the felt pads applied to the cone material - but he is the one to pose an answer to that question. His design looks doable in the DIY sort of way - so I'm headed that way 1st.

But the science looks very interesting! I can feel my mental gears turning - but then there is a lot of rust there!
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Old 19th March 2007, 10:48 PM   #65
BudP is offline BudP  United States
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Default Secrets revealed

Crank up the WD 40 machine... here we go.

The first thing done was to remove all of the internal foam damping material. Second was to "letter" this block pattern , on the inside, using a flat acrylic model paint, right out of the bottle . This paint was applied directly to the titanium surface, aluminum surface and the bottom edge of the paper using Speed Ball A series, 1 to 5, calligraphy pens (the ones with a bent tip). The pattern template is supplied by printing on a sheet of paper, with printing and scaling provided by Corel Draw 4 or later. Cut the round pattern out, apply it to a thin cardboard stiffener and you are ready to "letter". The scaled pattern needs to be a bit smaller than a direct size, so it settles deeper into the top of the cone than where you are going to apply the pattern. This pattern application location is the bottom edge of each material stage. The same process is applied to the outer surfaces, in the same places, though moved up a bit due to the glue overlap. In this case the ring printed by Corel needs to have the center cut out and it needs to be slightly larger than the applied pattern so that it will sink towards the bottom, underneath where the pattern is to be lettered.

The pattern does not need to be particularly precise so skill needs are rudimentary and if you can hold a calligraphy pen you can perform the needed activity. Best to learn on cheap paper speakers first. And, you will be amazed by how good these things really are.

Application of the conformal coating, on metal surfaces is only over the pattern, not the entire metal surfaces. For the paper you can apply it over all of the cone material, for much deeper bass as it will stiffen the paper, or just over the pattern for what has always been available.

Since this process adds mass only on the transverse wave boundary layer, the amount of mass needed is infinitesimal compared to what is needed to mass damp the entire driver surface. This is true regardless of materials or frequencies being controlled and works as well in infrasonic as it does in ultrasonic, though the pattern is comprised of really tiny blocks of printed material in the ultrasonic realm.

To experiment with dome tweeters and other small radiators you will need to acquire a range of technical lettering pens from the days of yore when mechanical drawings were done by hand on vellum paper. Since this is a scalar architecture, with the same number of blocks for any given ring diameter you will need some pretty fine points and to cut the acrylic paint with water by 10% or so.

Yes, I am the mad fool who developed this, so I can provide you with a Corel file should you be interested in experimentation.

The claims I can make are quite extensive but the one that I really like the benefits of the most are the resulting infinite resolution of micro dynamic signals and the addition of many dB of headroom before compression sets in. All of the information revealed by the process has always been there, just unintelligibly presented as noise, due to corruption by standing waves.

Also, what is really being done here is to speed up, or slow down, the wave front speed over the entire surface, to exactly that speed needed to emit a coherent wave front into the air, as the impulse traverses the driver surface. The white paper tests, shown on the last two pages, clearly indicate that more energy is getting off of the driver surface, before the final terminus of the tweeter in use.

Bud
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Old 20th March 2007, 12:08 AM   #66
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Hi Bud

Thanks for the info - and I personally would replace the phrase "mad fool" with "mad scientist". I'm a bit familiar with standing wave theory in airfoil designs - but that is a different application. In electronics and waveguide theory there are some applications especially used in phased array radar systems the traveling wave tubes - again a different application. But air can be considered as a "fluid" when considering the physics involved with compression and resistance to flow. The added problem with air is that it can be compressed where most fluids cannot. I understand your theory on the break-up of the standing waves with your EnABLE pattern which you have patented and I have taken the time to look over your patent at the USGPO. I took particular interest in the application of the pattern around the baffle of the speaker and on the surface of a dome shaped speaker - which might be of use in this type of project. I also took note of the math calculations used in the patent and considered doing just what you said when you stated to draw it up Coral Draw (or something of that sort). I was considering printing it out on a thin sheet of vellum and adhere it to the speaker cone but I was unsure as to what type of material was being used to perform the actual mechanical breakup of the standing wave. I was considering using some speaker dope and powered felt as a place to start and was also considering material to use on the speaker baffle - perhaps some cut up sections of felt pad. But 1st things 1st - I think Covey said that - Build a reference speaker as a base from which to work and compare and mamboni's design seems to be a very good starting point. I should also point out that I haven't been fooling around with audio since the mid 70's when I used to repair them. I used to have a complete set of those nice pens when I designed PWB's the old fashioned way - with Bishops red & blue tape on a precision grid - then I touched up the photo dropouts with the pins.

Isn't something similar to your EnABLE pattern being used to breakup rip tide currents? I seem to remember something like that in Popular Science. BTW - have you ever looked into an application for use with SONAR - might be something there.
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Old 20th March 2007, 12:59 AM   #67
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Default damping vs damping

I have not used any materials except the acrylic paint to create the blocks with. I suspect others will work as this does seem to be a local mass interruption, in an area that is inherently low mass and high energy per sq CM. The paint has always performed well on every surface I have tried, and since I have been fooling around with this since 1973, there are a lot of treated surfaces by now.

That it works on incident surfaces is also quite interesting. Relieves the normal diffraction at the edges of boxes and other deflection plates. Use in horns and drivers is quite noticeable with more energy density in the air, very few reflection artifacts in the horns and a general lack of horn "cry" due to the standing waves that populate most horn flares.

With the average speaker box treated and all drivers also treated the box disappears from the sound field and no artifacts give rise to it's reappearance, and the perceived sound field is immense. Done properly there are no "hot spots" at any frequency and images with multiple frequencies or a range of frequencies extending across more than one driver are pin point in their placement, with respect to our ear / correlator / conscious comprehension, and do not wander due to frequency changes, even across differing types of radiators.

This is of course some kind of "speaker holy grail" too good to be true and you can be sure that Not Invented Here has been the only response I have received from those very knowledgeable folks practicing their own form of this black art. To very good results by the way as the EnABL process has far less effect upon modern speakers than it did 30 years ago. Now it pretty much just accomplishes the original goal of eliminating transient standing waves, by making it impossible for them to form in the first place, without altering any of the other tonal and transient events in any way I have been able to measure. Certainly distortion plots and the included traces of various even and odd order HD are not visibly altered.

I was cautioned many year ago by a naval engineer not to mention Sonar in conjunction with this process as the government would and easily could co opt it, without paying me a penny and enforce my silence about the process and it's benefits.

Thanks for your thoughts, it is refreshing.

Bud
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Old 20th March 2007, 02:10 AM   #68
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Hello Bud:

You're EnABL approach to transverse wave termination is ingenious. Forgive my simplistic analysis, but your pattern of squares is behaving like a virtual diffraction grid, cause optimal phase cancellation in as much as the speed (and phase) of the wave are shifted as it traverses the stiffer lower impedance square-treated cone surface. Now, this in effect blurs the virtually cone-surround boundary, making the cone appear as an infinitely long transmission line. Your solution is elegant and simple. And I think I would be most interested in utilizing it in a future Walsh driver. I admit that I do not understand how the distribution of the squares is calculated for the woofer cone however.

I wanted to discuss the felt approach I implemented vis-a-vis a comment you made about it being mass loading. When I conceived the felt approach, the idea of adding progressive mass to the cone to achieve wave termination and simulate an infinite transmission line was the intuition. However, I discovered something unexpected - the felt fabric is incredibly light. In fact, after the felt treatment the Fs of the woofer is lowered no more than 1-2 hz. Yet the wave terminating ability of the felt is extraordinary. I believe there is something else at work here, far more important than mass: the felt consists of thousands of fibers. I believe the fibers are acting as a huge surface and providing for a much more efficient coupling of vibrating cone surface with air. Normally, the cone-air interface is a very inefficient due to the very different acoustic impedances of solid paper and air. The felt dramatically increases the effective surface area of the cone - many tines over. The best analogy I can think of is the small intestine, which to the naked eye is lined my a smooth pinky mucosal surface. But, under the microscope the surface is covered by billions of tiny hairs (villi), and ultrastructurally, each of these villi have thousands of microvilli. The result is that the effective absorption area of the small intestine is increased over 100-fold.

One might ask: if the felt is increasing the efficiency of acoustic radiation from the cone surface, why does the woofer not become louder per input watt? The answer is that all these thousands of fibers each cause random sound cancelling phase shifts and are behaving more as a low Q reactive impedance. In a way, the felt fibers are acting as thousands of tiny versions of your EnABL squares. Of course, the low Q results from the fibers coupling well with air and efficiently wicking acoustic energy away from the cone into the air.

Based on listening, the felt surface treatment seems exceptionally selective in damping out the resonant stored energy and perceived white noise that normally plagues the paper cone in its upper pass band. The felt has little effect on the woofer when operating in it's lower pistonic band. The result is an incredibly quiet soundstage and exceptional clarity of midrange separation. Of course, this must be heard first hand to be judged for oneself. Do you per chance live near Pennsylvania?
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Old 20th March 2007, 02:20 AM   #69
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Hi Bud

Reading your bio I see that we share magnetics in common - but thread isn't about those sort of things. Perhaps I will PM you about a couple of thoughts there. I was thinking about baffles and the use of some paint mixed with fine sand silk screened on with a finish similar to fine sand paper. Silkscreen might also be a method with which to apply your pattern onto a speaker or other surface. I can feel the old mental rust beginning to break free. Retirement - I love the freedom - but it's a bit of a drag to not have all of my technical toys around to play with.
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Old 20th March 2007, 02:44 AM   #70
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Default Mamboni / EnABL

I have no doubt that you are actually providing what my EnABL process simulates, an infinite boundary to a cone terminus, by actually providing an essentially infinite boundary layer.

Very clever, and the first specific instance of the use of this powerful lever, an effective control of the boundary layer, to enforce this effect I have seen other than the process I worked out so long ago.

Hooray!!!!!.

A number of folks around the commercial side of the speaker industry are becoming aware of the problem with boundary layers and that the boundary layer is the only place to control it. As an example Dynavox uses filled polypropylene cones in their large diameter voice coil woofers. Of course this solution just eliminates any sort of boundary layer active control without actually eliminating the transient ringing, just it's duration.

I suspect that a combination of our processes would either be a spectacular success or an equally spectacular failure. I think we should collaborate.

Your description of the silence of the sound field around instruments, with no loss of reverberant information nor micro dynamic detail is very familiar to me. I listen to it almost daily, as I work with speaker cables and interconnect cables that can be tuned for how much dynamic color they preserve and, with excess, add to the energy passing through them. Both of these tools aid greatly in the design and vetting of the audio transformers that I am currently in the middle of the third round of R&D activity on.

Should we ask for a separate thread to continue this discussion on? I suppose we will have to have some private communications also.

I live in the Seattle area and am elderly enough that I do not travel much, so we may never meet. But what fun!

Bud
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