John,
I like it. May I use it? Can you fix one up utilizing a bull? Perhaps with raised tail?
Bud
I like it. May I use it? Can you fix one up utilizing a bull? Perhaps with raised tail?
Bud
Re: Re: Ear EnaBulled
Dang!
I just had that tattooed on!
Too late now, I guess... 🙂
planet10 said:
Dang!
I just had that tattooed on!
Too late now, I guess... 🙂
hopefully the tat is raised approx 0.0070" from surface...
i believe the patterns work for output devices...maybe you should tat your lips...might help your tone...
i believe the patterns work for output devices...maybe you should tat your lips...might help your tone...
Most of the time when I look at measurements, I like to see significant differences and understand the relationship with listening. Normally, but not always, you can distinguish between an improvement and just difference by looking at data.doorman said:
Alex,
I am not absolutely certain I am following your thoughts about fig 3. As I understand the shape, it is two baffle widths and four baffle heights (two per side). You could just make a box around the driver I suppose. Somehow that offends my sense of what works.
I do like fig 2. Quite seductive looking. If you make the blocks all the size that comes from the baffle width madness, it will work just fine, even thought the distance is rather more. I really do not think there is much diffraction horizontally from the two sectors, outside of the rectangle around the driver. You might obtain a slightly more transparent sound field, but I would wait to see what happens with the rectangle on the baffle, the patterns at the ends and the driver being EnABL'd. It may take you a year or more of upstream work, to begin to "run out" of ability to reveal electronics improvements.
Bud
I am not absolutely certain I am following your thoughts about fig 3. As I understand the shape, it is two baffle widths and four baffle heights (two per side). You could just make a box around the driver I suppose. Somehow that offends my sense of what works.
I do like fig 2. Quite seductive looking. If you make the blocks all the size that comes from the baffle width madness, it will work just fine, even thought the distance is rather more. I really do not think there is much diffraction horizontally from the two sectors, outside of the rectangle around the driver. You might obtain a slightly more transparent sound field, but I would wait to see what happens with the rectangle on the baffle, the patterns at the ends and the driver being EnABL'd. It may take you a year or more of upstream work, to begin to "run out" of ability to reveal electronics improvements.
Bud
planet10 said:
Planet10, I agree with you to a degree 🙂
Nobody should stop speaking about it, since it seems to be alot of fun doing this discussion. Well, i dont agree when you say one cant validate the performance scientifically. Objectively one can, subjectively one can not. You speak from a subjective point of view, i try to take an objective one, so we can never agree here, but i think thats fine as it is 🙂
Maybe i just would have liked to see some math backing the whole thing up. What i have learned in my studies is, that working theories in engineering or science in general are all math and a little bit of words to connect the math. here we have only words. thats why i think this theory is not usefull, its rather philosophy or an equivalent play of words than engineering.
I think, finite element simulations would be the way to go to see if this really works on a purely mathematical point of view. beyma have simulated their new cone technology this way, claiming a better performance because of it.
And as long as there is no math, which at least makes my head hurt while learning it (which is quite easy for the math to achieve), i agree with magnetar:
Magnetar said:
MaVo said:
Finite element analysis will only address the issue of the diaphragm itself, not the basis of the claim relating to the boundary layer.
The problem is that the entire hypothesis with regard to boundary layer is without merit. John k alluded to the key point that it seems that everyone missed altogether, not surprising given the lack of rigor in studying this situation and the desire to believe in it regardless of valid objective data. The key is in the basis of a boundary layer. I did a bit of on-line research to see just what is involved. The picture below graphically represents the situtaion with a boundary layer.
A boundary layer is only an issue when there may be a change in it due to flow of a viscous material over a boundary (a wall here or the surface of a driver). The boundary layer is where the viscous flow changes from free stream to laminar to turbulent. Any material that makes the surface not flat, as EnABL does, would make it more turbulent. As John said, turbulence is bad and makes for more chaotic air movement beyond said material, increasing distortion components, IF that was the effect.
The boundary layer alteration we're concerned with would occur if, and only if, there were air flow across the surface of the diaphragm. EnABL supposedly skirts the issue of the boundary layer, improving the driver's response to the signal. The problem, and the basic error in the hypothesis, is the assumption that there is any significant air flow over the diaphragm. There may be some tiny movement of air laterally over the surface, but the primary and overwhelming movement is that of the driver outward or inward as the transverse wave in the diaphragm material causes it to create a compression wave in the air, not air flow. The transverse wave in the diaphragm, excited by the coil movement, moves far faster in the diaphragm than in the air, so whatever signal is exciting the air at any point at the surface of the diaphragm would pass as a compression wave through the air and arrive at successively father points along the diaphragm much, much later than the compression wave generated at those farther points, even if it were a flow. But it's not a flow, it's a compression wave and it's also periodic.
Also, remember that the diaphragm is close to, but not absolutely, pistonic in that the deflection of the diaphragm is not significant until it is in the breakup region. But even that is not necessarily bad. Driver manufacturers have for years used and still do use this to advantage. The older, softer diaphragms used a combination of material, damping, geometry and flex to extend the response of a driver. Soft dome tweeters do so to this day. The doped paper mid-woofers also use this to advantage still. But there's one key point, none of the them have anything to do with alteration of the boundary layer phemonenon.
Aircraft manufacturers have to be highly concerned with the boundary layer on aircraft, especially wings, due to the air flow over the wings and along the body of the plane. Loudspeaker manufacturers don't have to be concerned with it at all, it's a non-issue.
On close scrutiny, EnABL and the boundary layer issue are without merit. The effects are to be found in the simple, well known issues of mass, damping and some possible added stiffness in the immediate region of the application.
I'm sure many here, especially Bud, will take issue with this, but here has not been anything presented to support the hypothesis other than words. Close scrutiny reveals that it is not supportable by the physics.
Dave
>>> This thread is getting more amusing than interesting!
Yes, the Enabled speaker cabinet and ear were funny. The Totem beak is great too. I will never forget Jeff Joseph putting m&m's on his speakers to improve the sound (he was joking of course). I thought he was very clever to poke fun like that.
I thought Enabeling was all about damping cone resonances? From that perspective i think it is a clever idea that should be audible - as long as the cone benefits from it. I do not know how all of this other stuff got clouded up into this mess of a thread. Maybe it is no better than placing dots of clay onto a cone. Regardless, if it has an audible benefit than let people do it or pay for it.
The clay and the pattern both changed the frequency response of the tested driver. That means the change could be measured and heard. Whether it alters the sound for better or worse is up to the listener.
Yes, the Enabled speaker cabinet and ear were funny. The Totem beak is great too. I will never forget Jeff Joseph putting m&m's on his speakers to improve the sound (he was joking of course). I thought he was very clever to poke fun like that.
I thought Enabeling was all about damping cone resonances? From that perspective i think it is a clever idea that should be audible - as long as the cone benefits from it. I do not know how all of this other stuff got clouded up into this mess of a thread. Maybe it is no better than placing dots of clay onto a cone. Regardless, if it has an audible benefit than let people do it or pay for it.
The clay and the pattern both changed the frequency response of the tested driver. That means the change could be measured and heard. Whether it alters the sound for better or worse is up to the listener.
Godzilla said:
Measured, yes. Heard, not necessarily. There are known limits to the audibility of differences (JND or just noticeable differences) and that ability differs from one person to the next as well as with the signal content (music or other). A measurable change is not in all cases audible. The converse, however, is true for loudspeakers if one makes the correct measurements. All changes in a driver's transfer response can be measured, but if it's small, it may take rigorous work to precisely determine it.
Yes, even if the change is the placebo effect.
Dave
dlr said:
Some good stuff there Dave. Certainly gave a digestible insight into a complex subject.
The problem is exactly what is happening when the cones physical properties are altered by the treatment. Taking it back to the simple FR change argument; Any physical property of the cone that's been modified will result in a FR change but what if you tried to level the playing field to see if more is at work the amplitude differences. A mostly effective method would be to EQ'd both a treated and untreated driver to be roughly equivalent and then listened for differences.
ShinOBIWAN said:
Excellent point. The one issue would be the power response. If the FR alterations don't affect the off-axis response to the same degree as it does the on-axis response, then when the on-axis (or testing axis) is equalized, the off-axis will not be equalized, therefore the power response will differ. This is where rigor in the methodology comes into play.
There is one other issue at play. When the raw frequency response of a driver is changed, this will alter its distortion profile. This profile is generally at the 30db and down level of output, so it's not evident in the frequency response transfer function. The non-linear distortion, being dependent on driver displacement, is affected directly by that raw frequency response, so even if the two drivers were equalized for the steady-state frequency response, the non-linear distortion will not be equalized. The implication is that the two drivers will have differences in response no matter the equalization. Differentiating this aspect from any other in an audibility test is very problematic from the start.
Dave
Hi all,
dlr, that picture of a BL isn't exactly what is happening. I have a couple of simple animations that show the basic acoustic BL behavior here. http://www.musicanddesign.com/BL_vidio.html
It might take a while to load. The top vid is an acoustic wave propagating over a flat surface with the wave front perpendicular to the surface. There are no BL effects considered. The blue line represents the variation of the surface pressure on the surface in time. The wave propagates from left to right at the speed of sound as indicated by the violet line. The red dot is the pressure variation at a point in the surface given by the stationary, vertical black line. The red line is the variation in fluid particle velocity at increasing distance from the surface. They go forward and backward as the pressure changes as indicated by the arrows.
The second figure shows what happens when BL effects are included. Nothing changes but the particle velocity at the surface must equal the surface velocity, zero in this case. The BL at 1k Hz is about 0.002" thick. At 100 Hz it's about 0.006" thick and at 10k Hz it's about 0.0006" thick. Above the edge of the BL the wave propagation is the same as w/o a BL. In the BL the only difference is that the varying pressure forces are balanced by viscous dissipation (friction) instead of by the changes in velocity.
The third figure is supposed to show how the particle velocity at two different positions on the surface can be going is different directions (a time lag). Sorry that the right one moves around a little.
To consider the effects of the BL on the enable process consider three cases: 1) the BL is much thicker than the height of the patch. The result is effectively that the patch as no effect for several reasons. The BL thickness goes like sqrt (1/f) = sqrt (WL/C) where WL = wave length and C is sound speed. If the BL is much thicker than an enable patch then the wave length is even bigger relative the enable patch. The enable patch is buried well inside the BL and has little effect on anything.
2) The enable patch is much higher than the BL thickness. In this case it is the BL which has no impact on the interaction between the wave propagation and the enable patch. It reduces to a simple diffraction problem. However, unless the patch is very tall, it may still small compared to wave length (if the speed of sound is given in inches/sec and the BL and wave length are measured in inches, then the wave length is about 100 time the BL thickness.)
3) The patch is on the same order as the BL thickness. This is a more complex case, but since the BL is dissipative, removing energy from the acoustic wave at the surface, the worst case (maximum impact on wave propagation at the enable patch) occurs when we consider the case of no BL.
The vids are pretty crude but they may help the discussion.
dlr, that picture of a BL isn't exactly what is happening. I have a couple of simple animations that show the basic acoustic BL behavior here. http://www.musicanddesign.com/BL_vidio.html
It might take a while to load. The top vid is an acoustic wave propagating over a flat surface with the wave front perpendicular to the surface. There are no BL effects considered. The blue line represents the variation of the surface pressure on the surface in time. The wave propagates from left to right at the speed of sound as indicated by the violet line. The red dot is the pressure variation at a point in the surface given by the stationary, vertical black line. The red line is the variation in fluid particle velocity at increasing distance from the surface. They go forward and backward as the pressure changes as indicated by the arrows.
The second figure shows what happens when BL effects are included. Nothing changes but the particle velocity at the surface must equal the surface velocity, zero in this case. The BL at 1k Hz is about 0.002" thick. At 100 Hz it's about 0.006" thick and at 10k Hz it's about 0.0006" thick. Above the edge of the BL the wave propagation is the same as w/o a BL. In the BL the only difference is that the varying pressure forces are balanced by viscous dissipation (friction) instead of by the changes in velocity.
The third figure is supposed to show how the particle velocity at two different positions on the surface can be going is different directions (a time lag). Sorry that the right one moves around a little.
To consider the effects of the BL on the enable process consider three cases: 1) the BL is much thicker than the height of the patch. The result is effectively that the patch as no effect for several reasons. The BL thickness goes like sqrt (1/f) = sqrt (WL/C) where WL = wave length and C is sound speed. If the BL is much thicker than an enable patch then the wave length is even bigger relative the enable patch. The enable patch is buried well inside the BL and has little effect on anything.
2) The enable patch is much higher than the BL thickness. In this case it is the BL which has no impact on the interaction between the wave propagation and the enable patch. It reduces to a simple diffraction problem. However, unless the patch is very tall, it may still small compared to wave length (if the speed of sound is given in inches/sec and the BL and wave length are measured in inches, then the wave length is about 100 time the BL thickness.)
3) The patch is on the same order as the BL thickness. This is a more complex case, but since the BL is dissipative, removing energy from the acoustic wave at the surface, the worst case (maximum impact on wave propagation at the enable patch) occurs when we consider the case of no BL.
The vids are pretty crude but they may help the discussion.
This is just a quick demonstration of concept results.
The JX92S with gut feeling altered pattern according to some concepts I mentioned very early in the thread:
Here are some comnparisons with also the toopasted one and clean one I posted earlier.
The JX92S with gut feeling altered pattern according to some concepts I mentioned very early in the thread:
An externally hosted image should be here but it was not working when we last tested it.
Here are some comnparisons with also the toopasted one and clean one I posted earlier.
An externally hosted image should be here but it was not working when we last tested it.
john k... said:
Thanks for clarifying. The part that I still don't see is how there is any movement of air laterally across the surface. If it were a point source movement that caused a hemispherical wave expansion leaving the surface, I could understand that. But given that it's a vertical movement of the entire diaphragm and not a single point, there should not be any (or at least only small) movement of air particles parallel to the plane of the diaphragm surface, except for the area of breakup.
This is for the driver, of course. The baffle is another issue and will see parallel movement due to the compression wave, giving rise to edge diffraction, of course. Then I see where your points come into play more.
Dave
If the pattern is higher than the laminar BL, flow behing the pattern is turbulent, thus the shear stress is reduced and wave propogation would change. But this also depends on the direction of wave direction explansion rate as may be effected by a phase plug. The steep slope of the W3-1285 phase plug is what I think causes no measurable difference when I put patterns on the phase plug.john k... said:
MaVo said:
There is no set of measurements that completely characterize a loudspeaker, or an amp for that matter. Measurements are a design tool, not a validation tool. And math is only as good as the assumptions you choose to start with.
dave
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