Hi all. Still lurking around this thread...
Thanks John for the diagrams... I think that I can almost understand what you are suggesting here albiet in a probably superficial manner. Let me demonstrate the shallowness of my knowledge with a couple of questions.
1. Am I right in saying that Bud's hypothesis was that the sound wave being "altered" is a surface wave, i.e. In the air just in front of the cone, and that John is refferring to a wave being transmitted within the cone material?
2. Am I right in saying that in Johns model, the frequencies are being altered by the pattern resulting in a mutitude of "more random" "corrupted" frequencies being emanated from the speaker (at higher, perhaps less audible fequencies) instead of fewer less random "corrupted" frequencies in the standard driver?
3. Am I totally wrong in thinking that in the enabled driver in Johns model the wider range of frequencies will be of smaller amplitudes at each frequency point you measure?
Please dont shoot me down if I am getting the wrong end of the stick here, I am just trying to get my head around the debate.
Blair
Thanks John for the diagrams... I think that I can almost understand what you are suggesting here albiet in a probably superficial manner. Let me demonstrate the shallowness of my knowledge with a couple of questions.
1. Am I right in saying that Bud's hypothesis was that the sound wave being "altered" is a surface wave, i.e. In the air just in front of the cone, and that John is refferring to a wave being transmitted within the cone material?
2. Am I right in saying that in Johns model, the frequencies are being altered by the pattern resulting in a mutitude of "more random" "corrupted" frequencies being emanated from the speaker (at higher, perhaps less audible fequencies) instead of fewer less random "corrupted" frequencies in the standard driver?
3. Am I totally wrong in thinking that in the enabled driver in Johns model the wider range of frequencies will be of smaller amplitudes at each frequency point you measure?
Please dont shoot me down if I am getting the wrong end of the stick here, I am just trying to get my head around the debate.
Blair
john k... said:
Because of the increased stiffness at the pattern blocks, is it possible that it creates a type of "stalling" of the transverse waves travelling from the voice coil (in the direction of the surround) through the cone as they meet a resistance due to the density/stiffness change?
Gotcha. I had to re-read that a few times to properly visualize what you're saying.
I am having trouble figuring it out though.....there seems to be (in my mind) a conflict of what the pattern blocks could be doing (on the one hand) that they aren't doing (on the other hand).
If there were only the outer set of pattern blocks......but there are an inner set as well, so wouldn't there be a bunching up at the first set of blocks?......a heavy concentration of waves and reflections?
But couldn't the inner and outer patterns be simply damping the cone?
Ok, now I think it's too early in the morning for me to see this clearly now...
Cheers
I struggle with this, too
...the energy from the voice coil enters the cone...the energy travels through the cone (ok so far?)...what influences (determines) the portion of the energy that is radiated from the cone & the portion of the energy that remains in the cone?
...the energy from the voice coil enters the cone...the energy travels through the cone (ok so far?)...what influences (determines) the portion of the energy that is radiated from the cone & the portion of the energy that remains in the cone?
John K,
I have these same thoughts, though at a slightly less rigorous level, and have been thinking about them since first encountering bending wave theory. Two more things to add.
The transverse waves do have a form of memory, in that they have a vector. This does not alter their activities, obviously, but may have relevance to their initial traverse and potential re traverse at either end of the cone.
Second is to consider how the transverse waves are affected by their placement on a dome. Placement pattern is the same regardless of whether the dome is attached to a cone or is free standing.
I bring this up now, to point out the interactive nature between cone and dome, in a typical cone driver. The amount of gloss coat, used in conjunction with the overall patterns, will determine how much energy, above 1 kHz or so, is emitted as a "sweet spot" on axis. This is a secondary question, while investigating what the pattern may be doing, but it does provide a precursor and you should keep your thought processes open to it.
I do want to point out that just this amount of discussion was utterly heretical 30 years ago. I still do not find many professionals, in the field of speaker design, who utilize the notion of transverse waves being an important portion of a drivers output. Hence the continued march toward perfect piston performance, with the "break up mode" that transverse waves eventually bring about, being shunned as the uncontrolled event it is.
Just so everyone knows, I do approve of where this discussion is going and I agree with John about not coloring his thoughts with listening to the behavior of a treated driver. Hopefully your investigations and thoughts will bear more fruit than mine did, when I thought my way through these questions and eventually ended up with boundary layers.
The goad at the time was the gross difference in audible performance between the then state of the art untreated driver, and it's performance when treated. This situation has improved over the years, through materials science, but the difference is still great enough to force your thoughts into desperate measures, to explain that difference and the seeming insignificance of the method used to cause it.
Bud
I have these same thoughts, though at a slightly less rigorous level, and have been thinking about them since first encountering bending wave theory. Two more things to add.
The transverse waves do have a form of memory, in that they have a vector. This does not alter their activities, obviously, but may have relevance to their initial traverse and potential re traverse at either end of the cone.
Second is to consider how the transverse waves are affected by their placement on a dome. Placement pattern is the same regardless of whether the dome is attached to a cone or is free standing.
I bring this up now, to point out the interactive nature between cone and dome, in a typical cone driver. The amount of gloss coat, used in conjunction with the overall patterns, will determine how much energy, above 1 kHz or so, is emitted as a "sweet spot" on axis. This is a secondary question, while investigating what the pattern may be doing, but it does provide a precursor and you should keep your thought processes open to it.
I do want to point out that just this amount of discussion was utterly heretical 30 years ago. I still do not find many professionals, in the field of speaker design, who utilize the notion of transverse waves being an important portion of a drivers output. Hence the continued march toward perfect piston performance, with the "break up mode" that transverse waves eventually bring about, being shunned as the uncontrolled event it is.
Just so everyone knows, I do approve of where this discussion is going and I agree with John about not coloring his thoughts with listening to the behavior of a treated driver. Hopefully your investigations and thoughts will bear more fruit than mine did, when I thought my way through these questions and eventually ended up with boundary layers.
The goad at the time was the gross difference in audible performance between the then state of the art untreated driver, and it's performance when treated. This situation has improved over the years, through materials science, but the difference is still great enough to force your thoughts into desperate measures, to explain that difference and the seeming insignificance of the method used to cause it.
Bud
Re: I struggle with this, too
The power radiated is given by the real part of the radiation impedance times the surface velocity of the cone squared. The radiation impedance is a function of the fluid into which the driver is radiating (air). So once again we see that it all comes down to how the surface of the cone moves.
Ed LaFontaine said:
The power radiated is given by the real part of the radiation impedance times the surface velocity of the cone squared. The radiation impedance is a function of the fluid into which the driver is radiating (air). So once again we see that it all comes down to how the surface of the cone moves.
BudP said:
My point is that for a wave traveling in a given direction with given amplitude how the wave got there isn't relevant.
Sorry I don't follow.
John K,
Sorry, This should have read:
Second is to consider how the transverse waves moving through a dome are affected by the placement of the block patterns on the dome. Placement pattern is the same regardless of whether the dome is attached to a cone or is free standing.
Bud
Sorry, This should have read:
Second is to consider how the transverse waves moving through a dome are affected by the placement of the block patterns on the dome. Placement pattern is the same regardless of whether the dome is attached to a cone or is free standing.
Bud
The problem with this theory is that the patterns must have sufficient weight to be able to reflect waves as mentioned, otherwise they are floating on the wave instead of acting as a wall. Additionally, if it started to have effect, as a floating device, the relationship between the ploat and the wave would be such that the wavelength would have to be so small that it would be probably in the range of 40KHz and up.john k... said:
soongsc said:
No. The reflection is not due to the mass directly, reflections occur if there is an inhomogeneity in the cone, to include any material in contact with the cone. Applying a material that is different than the cone itself not only provides another path through which part of the wave will travel, but it also stiffens that area of the cone such that it is an inhomogeneity and will reflect, no different than for the surround. It's a junction between two different materials and if it is not a perfect impedance match such that there is total damping of the wave, some of the energy is going to reflect. Keep in mind that this is a transverse wave that creates the compression wave in the air via the cone [I/surface] to air interface, whatever that surface is.
Consider that if what you said were true, then spraying the entire surface with a very thin layer of some material, any material, would have no effect whatsoever. We know that this is not the case.
Dave
OK, question. If I follow this, the transverse wave/movement of the cone surface interacting with the EnABL pattern is the theory here. Not boundary layer, not anything once the sound wave impulse leaves the surface of the cone (sorry if my terminology isn't quite accurate here...). My question is, wouldn't the magnitude of this surface wave be greatly influenced by the material of the cone? I.e. if the cone was made of metal or some similarly rigid material, wouldn't we expect this transverse wave to be smaller?
OK, I obviously don't know the answer to that, but if it is yes, and the assumption is that EnABL interacts with this wave and not at any other level, then wouldn't if follow that EnABLing such rigid cones would have MUCH less effect than doing so to paper or similar cones? And what would be the effect on treated cones such as Planet10 uses? Has anyone treated such rigid cones (if my assumption about rigidity even holds...), and have those shown similar effects?
Thanks for humoring my beginner questions,
Carl
OK, I obviously don't know the answer to that, but if it is yes, and the assumption is that EnABL interacts with this wave and not at any other level, then wouldn't if follow that EnABLing such rigid cones would have MUCH less effect than doing so to paper or similar cones? And what would be the effect on treated cones such as Planet10 uses? Has anyone treated such rigid cones (if my assumption about rigidity even holds...), and have those shown similar effects?
Thanks for humoring my beginner questions,
Carl
Carl, Maybe soongsc will respond. His efforts have included metal domes and yes, there is a recognition that metal domes respond differently to the EnABL treatment.
Thanks for the dialog and sketches John...
Agreed
Further agreed that the EnABL bands are producing reflections/transmissions.
My curiosity becomes focussed on the qualities of those transmissions, particularly in comparison with those transmissions from the junction of the VC and/or surround with the cone.
Thanks for the dialog and sketches John...
Agreed
Further agreed that the EnABL bands are producing reflections/transmissions.
My curiosity becomes focussed on the qualities of those transmissions, particularly in comparison with those transmissions from the junction of the VC and/or surround with the cone.
CarlP,
I will be looking into this very question over the coming week. Soongsc did indeed apply EnABL to a metal cone, the same I will be working with, a Jordon JX92S cone and dome.
To date, application to aluminum center domes, polycarbonate domes and leaf tweeters, and aluminum ribbon ends have all provided the same type of change, with downward going detail and dynamic color increasing, and, also allowing extended SPL before onset of audible distortion, with a much more benign character to that onset. These characteristics are found in all but one driver I have treated to date.
Soongsc did not actually listen to his test cone. Like John K, he wanted to be free of subjective evaluations, while he explored the patterns. He has provided some valuable test data and some controversial test data to this thread.
In addition he has used EnABL as a spring board to find other patterns and sets of shapes that, based upon CSD plots he has provided, move well beyond what EnABL provides. I have not heard these devices and don't actually ever expect to.
However, I commend his efforts and hope that others can also use EnABL for their interests. Even if that is just to enjoy more musical value from your drivers than was available before, while awaiting professional applications, after suitable research has occurred.
Bud
I will be looking into this very question over the coming week. Soongsc did indeed apply EnABL to a metal cone, the same I will be working with, a Jordon JX92S cone and dome.
To date, application to aluminum center domes, polycarbonate domes and leaf tweeters, and aluminum ribbon ends have all provided the same type of change, with downward going detail and dynamic color increasing, and, also allowing extended SPL before onset of audible distortion, with a much more benign character to that onset. These characteristics are found in all but one driver I have treated to date.
Soongsc did not actually listen to his test cone. Like John K, he wanted to be free of subjective evaluations, while he explored the patterns. He has provided some valuable test data and some controversial test data to this thread.
In addition he has used EnABL as a spring board to find other patterns and sets of shapes that, based upon CSD plots he has provided, move well beyond what EnABL provides. I have not heard these devices and don't actually ever expect to.
However, I commend his efforts and hope that others can also use EnABL for their interests. Even if that is just to enjoy more musical value from your drivers than was available before, while awaiting professional applications, after suitable research has occurred.
Bud
Hmmm. The Jordan is exactly what I had in mind. However, having read over their site,
it seems they specifically design their drivers to encourage this kind of transverse wave for upper frequencies (OK, so that's not the intent, but it would seem to be the effect of their thin metal foil approach). Therefore, I'm not sure that driver provides the stiffness I was thinking about.
The driver I'm thinking about might not be any good at sound reproduction, but the idea is that it would dampen the transverse wave and therefore the effect of EnABL. The idea would be to find such a driver and EnABL it for blind comparisons to see if the rigid cone has less effect due to EnABL than less rigid drivers. If there is a similar effect for the listener, then I'd wonder if it was time to bark up another tree...
Carl
Carl
I do not know of any driver that is as rigid as you seem to want to look at. I have some polypropylene woofers and unused mid woofers that are very rigid. Made by DynaVox. The woofers took quite a large amount of gloss to get them to work as well as the Vifa 3 inch mid dome they are paired with. Crossover is at 800 Hz.
The patterns alone made them clearer, but the effective transient signal response was, in their untreated and EnABL patterned state, not a match for the Vifa dome.
They are now, but just. Audibly they miss the upper bass edge to some musical instruments, but lower crossover points compromise the mid range too much. Just another trade off, but both drivers are equally detailed, so it is a bearable one.
Perhaps other readers and lurkers can suggest some appropriate devices.
Bud
I do not know of any driver that is as rigid as you seem to want to look at. I have some polypropylene woofers and unused mid woofers that are very rigid. Made by DynaVox. The woofers took quite a large amount of gloss to get them to work as well as the Vifa 3 inch mid dome they are paired with. Crossover is at 800 Hz.
The patterns alone made them clearer, but the effective transient signal response was, in their untreated and EnABL patterned state, not a match for the Vifa dome.
They are now, but just. Audibly they miss the upper bass edge to some musical instruments, but lower crossover points compromise the mid range too much. Just another trade off, but both drivers are equally detailed, so it is a bearable one.
Perhaps other readers and lurkers can suggest some appropriate devices.
Bud
I would be very interested in the driver Bud says doesn't respond to EnABL. There might be a few answers there.
As to the rigid driver: if one imagines some kind of limit such as a perfectly rigid driver we have a piston (most folks' idea of a perfect driver ;-) ). I cannot imagine, right or wrong, that EnABL would have much effect on that. To find an actual one, one might have to look at long-throw subwoofers. Unfortunately these would have much reduced response in the frequency ranges of interest (I suppose). Or, damp the *c@3 out of a driver with some material that doesn't become 100% firm such as sorbothane.
It might not have much purpose though, I fear. And you won't have much use for it later.
As to the rigid driver: if one imagines some kind of limit such as a perfectly rigid driver we have a piston (most folks' idea of a perfect driver ;-) ). I cannot imagine, right or wrong, that EnABL would have much effect on that. To find an actual one, one might have to look at long-throw subwoofers. Unfortunately these would have much reduced response in the frequency ranges of interest (I suppose). Or, damp the *c@3 out of a driver with some material that doesn't become 100% firm such as sorbothane.
It might not have much purpose though, I fear. And you won't have much use for it later.
JacquesToo,
Electro Voice TH350 with phenolic diaphragm. I treated all available surfaces of pole piece, dome, compression chamber, phase matching tunnels, phase plug, horn throat and flare edges. I had one other, untreated, TH350 for a reference, with the same age and mfg. of the dome driver.
Before treatment they were closely balanced, both very sweet, dynamic and as colorful in high frequencies as I had heard to that point. Afterwards they were as identical as they had been, before I treated one of them. No audible difference, plus or minus.
Bud
Electro Voice TH350 with phenolic diaphragm. I treated all available surfaces of pole piece, dome, compression chamber, phase matching tunnels, phase plug, horn throat and flare edges. I had one other, untreated, TH350 for a reference, with the same age and mfg. of the dome driver.
Before treatment they were closely balanced, both very sweet, dynamic and as colorful in high frequencies as I had heard to that point. Afterwards they were as identical as they had been, before I treated one of them. No audible difference, plus or minus.
Bud
justblair said:
Assumming for the moment that this is indeed a potential mechanism, could it be an analog to the dither insterted into a digital signal in a CD player?
dave
I think my original post already answers the issue you have addressed in the first paragraph.dlr said:
In the second paragraph, whether or not spraying material on the surface will make a difference or not depends on the actual application. I have two 6.5" metal cone drivers, one with sprayed material and one without. Both did not accomplish what I was looking for. There are more material characteristic properties involved than you think.
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