I 'm learning a whole lot of stuff. Whether it's correct stuff is another matter.
If I summarize, I’d appreciate it if perhaps someone will take it apart.
If sound exported into diaphragm is not totally damped by its material, then it travels as a bending wave to the surround and reflects from it back to former interface and continue thus, until it is damped by diaphragm material. Under these conditions the diaphragm radiates modally.
And under these conditions, if I understand Ronc's recent posts about the nature of the radiation, very small (molecularly small?), parts of surface of the diaphragm will "kink' and "un-kink" and these "molecular" movements push air molecules, causing radiating sound we hear. Neat! (Same process allows badly built speaker box panels to radiate). I think an incorrect analogical experience is the subjectively loud white noise emitted from the surface of water in a kettle before it starts to boil. (unscientific measurement with Ratshack meter ~60 dB at @ 1ft, but there is a column of air above trapped by the sides of the kettle so lets say, ~ 50 dB).
Further, following Ron's posts, because shorter wavelengths find it easier to travel in the surface -the skin - then audible radiation is the higher frequency components of the signal that is originally exported into the diaphragm via former.* Longer wavelengths travel further inside the material and either dissipate or reflect between surround and former and, in doing this oscillation, perhaps even distort shape of the cone.
EnABL. The acrylic patches to the degree they work, bring four characteristics to the game: stickiness, density, stiffness, and pattern of distribution.
Stickiness. Acrylic certainly will form an intimate layer with a lot of things, paper for sure.
Stiffness. Acrylic is certainly stiffer than paper. Over the area of its coverage it will, to some degree, dampen skin effect radiation.
Density. Acrylic is denser than paper. Over the area of it's coverage, it will to some degree, dampen skin effect radiation.
Distribution. See below.
What happens when former bangs an impulse into diaphragm material:
Looking at the enABL patch from cross section view of diaphragm , its effect on the wavelengths traveling through the skin looks three fold: they push patch in their travel direction but because paper is viscoelastic, patch returns to position; they transfer into patch and find a much thinner, stiffer skin to "kink" and shorter wavelengths travel in it to create audible sound,** their longer components detour under patch. Energy is lost at each stage including impedance losses entering and leaving patch.
In plan view of diaphragm, following traveling direction of waves. Immediately behind patch there is area of lesser skin excitement, and wavelengths going through the gap between patches expend energy exciting that area, and then these wavelengths are processed by the patch in gap, and the process repeats for ensuing rows of in-the-gap blocks.
If the pattern of enable patches is arranged correctly, and their specific gravity and stiffness are sufficient, then it’s likely the area of the pattern could be a zone of great attenuation, or even a “black hole”, for some range of wavelengths.
I got curious about this and ransacked Google for a bit and found phononic, or sonic, “crystals” – periodic structures depending for their effectiveness on impedance mismatch in their materials. They generate bandgaps in the same fashion as solid state and optical crystals do. Phononic crystals operate in all kinds of dimensions and media and can be constructed of a huge variety of materials and can have application in the audible range. Looks like real science, unlike what I do.
http://www.google.com/advanced_search?hl=en
I think ronc probably hit it bang on.
I suspect folk with enABL'd diaphragms could check for bandgaps. This would be particularly cute if they have another unenABL'd speaker of same type.
………………………………………………………………………..
**This audible sound will be in concert with coincident universal radiating movement of the whole speaker cone. I believe this is the part of the process Bud refers to as lofting the wave into the air. I don’t think this has to with air flow - it has to do with redirecting bending waves so they either convert to heat or to planned audible sound or they divert into “depths” of material, traveling further and attenuating.
*Do these HF waves also act as carrier wave of LF? Are they modulated in some fashion?
If I summarize, I’d appreciate it if perhaps someone will take it apart.
If sound exported into diaphragm is not totally damped by its material, then it travels as a bending wave to the surround and reflects from it back to former interface and continue thus, until it is damped by diaphragm material. Under these conditions the diaphragm radiates modally.
And under these conditions, if I understand Ronc's recent posts about the nature of the radiation, very small (molecularly small?), parts of surface of the diaphragm will "kink' and "un-kink" and these "molecular" movements push air molecules, causing radiating sound we hear. Neat! (Same process allows badly built speaker box panels to radiate). I think an incorrect analogical experience is the subjectively loud white noise emitted from the surface of water in a kettle before it starts to boil. (unscientific measurement with Ratshack meter ~60 dB at @ 1ft, but there is a column of air above trapped by the sides of the kettle so lets say, ~ 50 dB).
Further, following Ron's posts, because shorter wavelengths find it easier to travel in the surface -the skin - then audible radiation is the higher frequency components of the signal that is originally exported into the diaphragm via former.* Longer wavelengths travel further inside the material and either dissipate or reflect between surround and former and, in doing this oscillation, perhaps even distort shape of the cone.
EnABL. The acrylic patches to the degree they work, bring four characteristics to the game: stickiness, density, stiffness, and pattern of distribution.
Stickiness. Acrylic certainly will form an intimate layer with a lot of things, paper for sure.
Stiffness. Acrylic is certainly stiffer than paper. Over the area of its coverage it will, to some degree, dampen skin effect radiation.
Density. Acrylic is denser than paper. Over the area of it's coverage, it will to some degree, dampen skin effect radiation.
Distribution. See below.
What happens when former bangs an impulse into diaphragm material:
Looking at the enABL patch from cross section view of diaphragm , its effect on the wavelengths traveling through the skin looks three fold: they push patch in their travel direction but because paper is viscoelastic, patch returns to position; they transfer into patch and find a much thinner, stiffer skin to "kink" and shorter wavelengths travel in it to create audible sound,** their longer components detour under patch. Energy is lost at each stage including impedance losses entering and leaving patch.
In plan view of diaphragm, following traveling direction of waves. Immediately behind patch there is area of lesser skin excitement, and wavelengths going through the gap between patches expend energy exciting that area, and then these wavelengths are processed by the patch in gap, and the process repeats for ensuing rows of in-the-gap blocks.
If the pattern of enable patches is arranged correctly, and their specific gravity and stiffness are sufficient, then it’s likely the area of the pattern could be a zone of great attenuation, or even a “black hole”, for some range of wavelengths.
I got curious about this and ransacked Google for a bit and found phononic, or sonic, “crystals” – periodic structures depending for their effectiveness on impedance mismatch in their materials. They generate bandgaps in the same fashion as solid state and optical crystals do. Phononic crystals operate in all kinds of dimensions and media and can be constructed of a huge variety of materials and can have application in the audible range. Looks like real science, unlike what I do.
http://www.google.com/advanced_search?hl=en
I think ronc probably hit it bang on.
I suspect folk with enABL'd diaphragms could check for bandgaps. This would be particularly cute if they have another unenABL'd speaker of same type.
………………………………………………………………………..
**This audible sound will be in concert with coincident universal radiating movement of the whole speaker cone. I believe this is the part of the process Bud refers to as lofting the wave into the air. I don’t think this has to with air flow - it has to do with redirecting bending waves so they either convert to heat or to planned audible sound or they divert into “depths” of material, traveling further and attenuating.
*Do these HF waves also act as carrier wave of LF? Are they modulated in some fashion?
H Frank,
Yes - still much more to think about - for all of us; including the 'nay-sayers' !
Hi Dave,
B200:
So your red trace is after driver treatment here, with fractionally lower cone resonance and fractionally lower impedance at higher frequencies.
By far the greatest change however appears at about 11.5kHz, where resonance behind the dust cap has been replaced by a slightly shorter path phase plug reflection of transverse waves.
Personally I find that high 'Q' behind-dust-cap resonance seriously obnoxious, and it can be damped by holding something soft but free to move against the centre of the dust cap.
I will shortly measure cap to pole face distance by making a mark on a needle pushed through until it hits the pole face.
It has been my (suggested above) observation that already activated air-side energies react against the cone in series with voice coil impedance and on-going output drive, and that that reactivity may be damped either by using something like a tube amp (SE), or a low value resistor in series with a SS NFB amplifier. The damping due to a series R between 1 and 4.7 ohms with a SS amp can very much improve mid-high reproduction clarity (where the dynamic voice coil impedance is rising anyway) without notably impairing transient capabilities, and I have found this with other drivers too, not just the B200.
Do Fostex drivers with a central dust cap hole have this same peak - I don't know, but I very much doubt it ?
For me the resonant chamber behind the B200 dust cap is a chronic affliction requiring irreversible corrective surgery, but have not yet decided upon which procedure to try first.
Maybe if a phase plug was elliptical such that it's dimensional relationship with the cone edge does not remain (reactively) constant ?
Also noted between your blue/red plots is improved damping about 400Hz - is that the blue tack frame damping, or cone treatment I wonder ?
Cheers ........ Graham.
Yes - still much more to think about - for all of us; including the 'nay-sayers' !
Hi Dave,
B200:
So your red trace is after driver treatment here, with fractionally lower cone resonance and fractionally lower impedance at higher frequencies.
By far the greatest change however appears at about 11.5kHz, where resonance behind the dust cap has been replaced by a slightly shorter path phase plug reflection of transverse waves.
Personally I find that high 'Q' behind-dust-cap resonance seriously obnoxious, and it can be damped by holding something soft but free to move against the centre of the dust cap.
I will shortly measure cap to pole face distance by making a mark on a needle pushed through until it hits the pole face.
It has been my (suggested above) observation that already activated air-side energies react against the cone in series with voice coil impedance and on-going output drive, and that that reactivity may be damped either by using something like a tube amp (SE), or a low value resistor in series with a SS NFB amplifier. The damping due to a series R between 1 and 4.7 ohms with a SS amp can very much improve mid-high reproduction clarity (where the dynamic voice coil impedance is rising anyway) without notably impairing transient capabilities, and I have found this with other drivers too, not just the B200.
Do Fostex drivers with a central dust cap hole have this same peak - I don't know, but I very much doubt it ?
For me the resonant chamber behind the B200 dust cap is a chronic affliction requiring irreversible corrective surgery, but have not yet decided upon which procedure to try first.
Maybe if a phase plug was elliptical such that it's dimensional relationship with the cone edge does not remain (reactively) constant ?
Also noted between your blue/red plots is improved damping about 400Hz - is that the blue tack frame damping, or cone treatment I wonder ?
Cheers ........ Graham.
soongsc said:
Sorry, Soongc. That is not at all what the theory indicates. But this isn't a classical boundary layer in the first place. This is a highly complex, oscillatory, transient, ever-changing BL which results due to the complex driver motion in response to the input signal.
In the most general terms a boundary layer is a fluid layer at an interface where there is a deviation in the behavior of a real fluid from that of an ideal, frictionless fluid. I will agree that the BL on a cone will make no difference here. The velocities are too small to alter the acoustic properties of the fluid, hence the propagation of wave through a boundary layer. If Bud's statement that the enabled patches are 0.015" thick, and that this is thicker than any BL, then even at 20 k Hz the wave length in air is some 45+ time BL thickness. That should ring some bells to anyone who understand propagation of acoustic waves.
AAAHHHH, finally, we have found the true path, a combination of mystic science (thank you dlr) and phonic crystals (thank you FrankWW). Not that I am objecting to either concept, they both work for me.
There ya go AJ, a freebie.
Bud
There ya go AJ, a freebie.
Bud
BudP said:
True path? Oh, please. Call it esoteric or something else if you want, that's just semantics.
The problem remains, there's no proof of any of it whatsoever. Any effects are fully consistent with classical driver theory. Inventing some new mechanism is unneeded to explain it and, so far, still just conjecture. John's posts are consistent with driver thoery and its not a little enlightening that you essentially ignore that part of the discussion.
Absent any proof (the situation as it stands today), would a reasonable person accept that which is consistent with the known physics that explains it or the conjecture that has no evidence? I know my answer.
Someone needs to provide some real data, not just increasingly complex conjecture. Certainly more than anecdotal evidence needs to be made available.
dlr
dlr said:
I was thinking about this the other day ... in general if you take a range of really good loudspeakers, there is no way to provide proof that one is better than another. This with the tools we have available to us. This with the tools available to some companies with pretty deep pockets and pretty good tools.
That every single person in blind or sighted tests (in my direct experience) has displayed non-verbal positive response to EnABLed drivers indicates to me that something positive is happening*. 30 years of watching people respond to hifi (and part of that my livelihood for a while) That is proof enuff to me. What tools & speculation we can apply to the problem to try to figure out exactly what is happening is an aid to figuring out how to make it better.
I would not dismiss Ron's sim so readily. His is a tool that (as far as i can figure -- ron can correct me) is as capable of simulating a real-world event as any (except maybe some of the really advanced stuff at Lawrence Livermore & similar)
And another point... the classical tools we have been asked to use to "prove" the issue are a development of the 5% of math that is "easy". As complexity theory has clearly shown, the other 95% can provide incredibly simple solutions to amazingly complex issues (and shown us just how complex others are)... the loudspeaker in the face of music certainly falls into this part of the complexity spectrum. It would be nice if classical techniquies can solve the problem of what & how )(and certainly the 1st place to look), but one needs to keep the mind open to the rest, because the more science looks at things the more they find that when you look really closely, classical just doesn't describe what is happening.
dave
dlr said:
Not to dispute your logic, but "known physics"?
Have the boundaries of "known science" (as understood in the classical sense of our current civilization) never been known to change, sometimes by pure serendipity?
I might also conjecture that regardless of the outcome of the raging debate regarding attempts at explanations for how/why EnABL "works", there is plenty of margin for error on the part of those hastily attempting to apply an abbreviated version of any the multi-stages of the treatment process. Interpretations of listening and measurements taken under those conditions are not likely to be representative.
Driver modification is to say the least a blend of "art" and "science", that many find a questionable pursuit - i.e. "just buy the right driver for the job in the first place".
It's certainly easy to understand that unsuccessful attempts can add momentum to the argument that it's a fool's game. I've heard drivers myself with which I'm familiar, that have been seriously compromised due to "one step too many".
dlr,
I couldn't agree more. As I understand it SY still plans to tear into this, from both tests based upon standard techniques and a double blind listening test. I haven't had anything to do with either the drivers chosen nor any of the parameters. MJK appears to have a set of treated and untreated drivers and is perhaps going to look into them. Again, I have had no part in this either.
At one point Dan Wiggins said he intended to provide both an anechoic lab and himself, to explore what is actually going on. However, after emailing me a eureka note from China, concerning using a pattern claimed to be very similar to mine, but left as an unscreened set of extruded blocks on the cone back side, at the main nodal resonance dispersal location, first discovered, or perhaps, first reported by Soonsgc, Dan has stopped answering any of my emails. I can only conjecture what this might mean, but I am assuming testing is no longer on offer.
Actually I rather like your "Mystical Science" moniker. It resonates well with other advanced concepts like cryogenic immersion. Might just as well be prepared to be tarred by the communal brush, accept my load of feathers and prepare for a brisk event with shinning steel rails.
Bud
I couldn't agree more. As I understand it SY still plans to tear into this, from both tests based upon standard techniques and a double blind listening test. I haven't had anything to do with either the drivers chosen nor any of the parameters. MJK appears to have a set of treated and untreated drivers and is perhaps going to look into them. Again, I have had no part in this either.
At one point Dan Wiggins said he intended to provide both an anechoic lab and himself, to explore what is actually going on. However, after emailing me a eureka note from China, concerning using a pattern claimed to be very similar to mine, but left as an unscreened set of extruded blocks on the cone back side, at the main nodal resonance dispersal location, first discovered, or perhaps, first reported by Soonsgc, Dan has stopped answering any of my emails. I can only conjecture what this might mean, but I am assuming testing is no longer on offer.
Actually I rather like your "Mystical Science" moniker. It resonates well with other advanced concepts like cryogenic immersion. Might just as well be prepared to be tarred by the communal brush, accept my load of feathers and prepare for a brisk event with shinning steel rails.
Bud
planet10 said:
The discussion is not about good and bad. Indeed there can be no proof of that whatsoever. "Better" has to be left to each individual. That is as subjective as anything can be.
Again, purely subjective and providing nothing with regard to the mechanism involved, the point of the discussion. This is a moot point and shouldn't be in any of the discussion on mechanisms. Once more, I and any other skeptics have always said from the beginning that change may occur. The attempts to define the mechanism are at issue. That is where evidence is needed.
Proof of what?
We all aspire to that goal. The tools are available for that now.
Dave
Well, for my ears ... enabl produces no audible fr changes (our hearing is very sensitive to these). This is what makes auditioning amps more difficult than speakers - fr is so similar.
It appears to remove (greatly reduce) something that is many db down from the main signal. (who called it fricative hash?).
So what technology can measure that? Would laser inteferometry at higher frequencies show what is causing this? I suspect it would look slightly different, and we would then argue bitterly about whether the differences seen were sonically significant or not.
And I can't see it in the cascade plots. The differences I see there just don't look big enough.
How about some sympathy for our poor long-abused cable-obsessed brothers over at the cable asylum. Why does resistance / capacitance / inductance not explain all cables? Similar problem.
(Perhaps too much McGuigan's Chardonnay tonight but what the heck).
It appears to remove (greatly reduce) something that is many db down from the main signal. (who called it fricative hash?).
So what technology can measure that? Would laser inteferometry at higher frequencies show what is causing this? I suspect it would look slightly different, and we would then argue bitterly about whether the differences seen were sonically significant or not.
And I can't see it in the cascade plots. The differences I see there just don't look big enough.
How about some sympathy for our poor long-abused cable-obsessed brothers over at the cable asylum. Why does resistance / capacitance / inductance not explain all cables? Similar problem.
(Perhaps too much McGuigan's Chardonnay tonight but what the heck).
Hi all
About a month ago I decided that i had to try this Enabl thing. Not wanting to betatest on my main speakers I went to my local recycling shop and found a pair of Philips speakers from the last mellenium.
These FR speakers sound surpricingly nice and has a much better soundstage than expected. Eager to get started I went and got some acrylic wall paint and a small brush. I know that this is not the prescribed medication, but other people seems to be doing fine with these.
I went ahead and painted the first rings on one speaker. Then I listened for a long time.
Then I painted some more. More listening ... More paint ... more listening.
Then I decided that maybe the paint had to dry for a few days.
Here one month later I pulled the speakers out again and gave them a good listening session.
The thing is that I can't say that there is much difference between the treated and the untreated speaker. Maybe a tiny, tiny bit and that wouldn't be for the better.
Im really hoping that I did something obviusly wrong and that you can point it out so i can try the other speaker.
Here is a few pictures:
About a month ago I decided that i had to try this Enabl thing. Not wanting to betatest on my main speakers I went to my local recycling shop and found a pair of Philips speakers from the last mellenium.
These FR speakers sound surpricingly nice and has a much better soundstage than expected. Eager to get started I went and got some acrylic wall paint and a small brush. I know that this is not the prescribed medication, but other people seems to be doing fine with these.
I went ahead and painted the first rings on one speaker. Then I listened for a long time.
Then I painted some more. More listening ... More paint ... more listening.
Then I decided that maybe the paint had to dry for a few days.
Here one month later I pulled the speakers out again and gave them a good listening session.
The thing is that I can't say that there is much difference between the treated and the untreated speaker. Maybe a tiny, tiny bit and that wouldn't be for the better.
Im really hoping that I did something obviusly wrong and that you can point it out so i can try the other speaker.
Here is a few pictures:
Attachments
Alan Hope said:
Because RLC is a very useful measure of cable electrical parameters, but a very useless measure of insanity.
cheers,
AJ
Constrained Layer Damping?
I have been reading this post with some interest and would like to chime in and propose that the ENABL treatment might be a form of constrained layer damping.
I have used a commercial constrained layer product designed (marigoaudio.com) and a DIY version made from cutting 3M damping sheets (available at amusicdirect.com) into squares of a few mmm in width on three different speakers. These have been placed near the edge termination a shown at the Marigo site. I have only used two, or four spots of constrained layer material on a cone. This modification has brought great increases in clarity, imaging, etc. However, Bud has mentioned one thing that struck me. That is the increase in measured and perceived sound level with ENABL, I get a noticeable increase in loudness on a constrained layer damping treated cone. I didn’t measure it, but treating one speaker of a pair let me tell quite clearly that the treated speaker was louder when both are playing.
The Marigo and 3M products consists of two outer stainless steel skins sandwiching an elastometer layer. However there are other products such as Dynamat which is typically used to damp car doors and floors that have an elastomer constrained by on only one surface.
For the typical ENABL treatment, I propose the possibility that the elastomer is cone material itself and the constraining layer is produced by the painted on layers. This is not a difficult picture in the case of soft cone drivers. However, Bud has mentioned success on metal cone drivers and I am not sure if constrained layer is produced in that case.
So, the point that I am interested investigating is whether the ENABL process could be a method of producing constrained layer damping that suppresses the transmission of transverse waves along the cone.
Constrained layer damping itself, is, from what I have seen, used industrially in noise and vibration suppression and I hope someone with some experience in its theory can provide some comments.
I have been reading this post with some interest and would like to chime in and propose that the ENABL treatment might be a form of constrained layer damping.
I have used a commercial constrained layer product designed (marigoaudio.com) and a DIY version made from cutting 3M damping sheets (available at amusicdirect.com) into squares of a few mmm in width on three different speakers. These have been placed near the edge termination a shown at the Marigo site. I have only used two, or four spots of constrained layer material on a cone. This modification has brought great increases in clarity, imaging, etc. However, Bud has mentioned one thing that struck me. That is the increase in measured and perceived sound level with ENABL, I get a noticeable increase in loudness on a constrained layer damping treated cone. I didn’t measure it, but treating one speaker of a pair let me tell quite clearly that the treated speaker was louder when both are playing.
The Marigo and 3M products consists of two outer stainless steel skins sandwiching an elastometer layer. However there are other products such as Dynamat which is typically used to damp car doors and floors that have an elastomer constrained by on only one surface.
For the typical ENABL treatment, I propose the possibility that the elastomer is cone material itself and the constraining layer is produced by the painted on layers. This is not a difficult picture in the case of soft cone drivers. However, Bud has mentioned success on metal cone drivers and I am not sure if constrained layer is produced in that case.
So, the point that I am interested investigating is whether the ENABL process could be a method of producing constrained layer damping that suppresses the transmission of transverse waves along the cone.
Constrained layer damping itself, is, from what I have seen, used industrially in noise and vibration suppression and I hope someone with some experience in its theory can provide some comments.
Seems that you are the only one that pointed out this error.🙂john k... said:
I agree that the movement of air is small such that any boundary layer cannot fully form, however the change in shear characteristics and it's effects on sound wave transmission might be of value to study when the lower magnitude effects and it's audibility are not masked by other forms acoustic energy of higher amplitude. I think it would be interesting to look into when I get to wave guides.
The dimensions of the pattern and spacing between the rectangles are not nearly as specified. Spacing between the rectangles are important! Slightly wider spacing might be better than too close.kaan said:
Re: Constrained Layer Damping?
Normally a properly treated one should sound cleaner, and like it has a darker background. Percussion instruments have more controlled timbre. The sound would still be quite relaxed even if you turn the volume up.
In my experience, if the treated one sounds louder, then there must be shifted resonance to a different frequency range.steely3 said:
Normally a properly treated one should sound cleaner, and like it has a darker background. Percussion instruments have more controlled timbre. The sound would still be quite relaxed even if you turn the volume up.
Could you show some so called cascade plots within the first 0.4ms range or so or whatever the smallest range you can get?Alan Hope said:
AJinFLA said:
Without doubt! And, rats, just as I was finally cured of my cable-insanity I'm suffering a severe bout of enabl-insanity!
Hi Kaan,
With respect, although the process is reputed to be forgiving in terms of technique, I do wonder a bit at your application. I used a smaller brush, giving more linear strokes aiming for the 2:1 ratio for each 'blob'. They did end up a bit round cornered, but pretty close in appearance to this guy's photographs.
Replikon photos
And there is no fr change I can hear, so your speakers WILL sound the same. The basic music signal appears to be unchanged - just the removal of some sort of low-level hash. And the feeling that - at a distance of a few feet, the sound is now coming from behind the speaker.
(Hmmm, all sounding very psycho-acoustic now!)
Alan
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