Retsel,
Just for clarity, which "above" are you referring to? Jon Ver Halen did a set of tests on treated and untreated Lowther PM6A drivers. The ones brought to the last RMAF show for the ad hoc comparison. They do have an extremely similar cone structure, with like materials.
The posts start here.
http://www.diyaudio.com/forums/showthread.php?postid=1275431#post1275431 post 414
Bud
Just for clarity, which "above" are you referring to? Jon Ver Halen did a set of tests on treated and untreated Lowther PM6A drivers. The ones brought to the last RMAF show for the ad hoc comparison. They do have an extremely similar cone structure, with like materials.
The posts start here.
http://www.diyaudio.com/forums/showthread.php?postid=1275431#post1275431 post 414
Bud
Ok, I have constructed some simple wave diagrams for a one dimensional radial slice through a driver cone for untreated and Enabled drivers. They represent a simplification of the real case, but the relevant physics is presented.
In this figure the cut of the driver is at the upper left. The center line is though the center of the VC. The cone extends from the VC to the surround with a radial length R, A transverse wave is initiated at the VC/cone interface and propagates outward to the surround where it is in part reflected back into the cone and in part transmitted to the surround. The reflect wave then travels back to the VC where it is again reflected back towards the surround. Each time the wave in the cone is reflected energy must be conserved so energy transmitted to the surround or VC is lost and results in a reduction in the amplitude of the wave.
Directly to the right is the wave diagram for this process. The cone VC junction is at the origin. The radial distance along the cone surface is the horizontal axis and time is the vertical axis. Assuming the wave in the cone travels at a velocity C1, then it take a finite amount of time for the wave to reach radial positions on the cone away form the origin. The line extending from the origin upward to the right represents the propagation of the original wave. If you go to some radial location on the cone, for example r1, and draw a vertical line to point of intersection with the line of propagation of the original wave, then a horizontal line back the vertical axis indicates the time at which the wave reaches that radial location. The further out in r the longer the time.
The line starting at the surround and sloping upward to the left represents the first reflection of the original wave from the surround. The small line sloping upward to the right at this point is the component of the wave transmitted to the surround. The next line, sloping upward to the right is the reflection from the VC/cone junction of the wave reflected from the surround. This pattern would continue until the wave energy is completely dissipated.
If we draw vertical lines at different radial locations, r1, r2, r3, the points where each vertical line crosses the wave propagation paths indicates the time when each wave or reflected wave reaches that radial position. Since the wave remains unaltered except for amplitude, we can think of each crossing as resulting in an imaginary source radiating into the air which is identical to the original wave but with a scaled amplitude and delayed by the time it takes for the wave to arrive at that radial location.
If the speed of sound in air is C, then the distance a wave travels from the cone surface towards a listener (on axis) over a time T is C x (T-t). From this we can produce the second plot which shows the distance the sound from each imaginary source travels towards the listener as a function of radial position.
We can collapse this information into a time train by dividing by computed distances by the speed of sound in air as shown at the bottom. This time train represents the arrival times of the information radiated by each imaginary source. In reality we would have an infinite number of such sources between the cone/VC junction and the surround, and the time train of the signal would be a continuous function of time, but the original signal would still be smeared in time unless the cone were reflection free and the time required to the wave in the cone to traverse the distance from VC to surround was much less than 1/f, where f is the frequency being radiated.
Now look at what could happen when an Enable treatment is made. The figure below considers this case:
The black lines represent the wave paths resulting from the reflections of the original wave from the surround and the VC. The red lines represent (some of) the additional reflections/transmissions due to the Enable pattern. I won't bother going into any arguments as to why the imaginary sources associated with the enable generated reflections/transmission must be much lower in amplitude than those associated with the original waves other than to say that it should be obvious that if there were of significant magnitude then the measured frequency response of the driver would necessarily be very different. I'm more than happy to go into this if someone wants to honestly discuss it, but I won't engage hand waving arguments as to why it ain't so.
An externally hosted image should be here but it was not working when we last tested it.
In this figure the cut of the driver is at the upper left. The center line is though the center of the VC. The cone extends from the VC to the surround with a radial length R, A transverse wave is initiated at the VC/cone interface and propagates outward to the surround where it is in part reflected back into the cone and in part transmitted to the surround. The reflect wave then travels back to the VC where it is again reflected back towards the surround. Each time the wave in the cone is reflected energy must be conserved so energy transmitted to the surround or VC is lost and results in a reduction in the amplitude of the wave.
Directly to the right is the wave diagram for this process. The cone VC junction is at the origin. The radial distance along the cone surface is the horizontal axis and time is the vertical axis. Assuming the wave in the cone travels at a velocity C1, then it take a finite amount of time for the wave to reach radial positions on the cone away form the origin. The line extending from the origin upward to the right represents the propagation of the original wave. If you go to some radial location on the cone, for example r1, and draw a vertical line to point of intersection with the line of propagation of the original wave, then a horizontal line back the vertical axis indicates the time at which the wave reaches that radial location. The further out in r the longer the time.
The line starting at the surround and sloping upward to the left represents the first reflection of the original wave from the surround. The small line sloping upward to the right at this point is the component of the wave transmitted to the surround. The next line, sloping upward to the right is the reflection from the VC/cone junction of the wave reflected from the surround. This pattern would continue until the wave energy is completely dissipated.
If we draw vertical lines at different radial locations, r1, r2, r3, the points where each vertical line crosses the wave propagation paths indicates the time when each wave or reflected wave reaches that radial position. Since the wave remains unaltered except for amplitude, we can think of each crossing as resulting in an imaginary source radiating into the air which is identical to the original wave but with a scaled amplitude and delayed by the time it takes for the wave to arrive at that radial location.
If the speed of sound in air is C, then the distance a wave travels from the cone surface towards a listener (on axis) over a time T is C x (T-t). From this we can produce the second plot which shows the distance the sound from each imaginary source travels towards the listener as a function of radial position.
We can collapse this information into a time train by dividing by computed distances by the speed of sound in air as shown at the bottom. This time train represents the arrival times of the information radiated by each imaginary source. In reality we would have an infinite number of such sources between the cone/VC junction and the surround, and the time train of the signal would be a continuous function of time, but the original signal would still be smeared in time unless the cone were reflection free and the time required to the wave in the cone to traverse the distance from VC to surround was much less than 1/f, where f is the frequency being radiated.
Now look at what could happen when an Enable treatment is made. The figure below considers this case:
An externally hosted image should be here but it was not working when we last tested it.
The black lines represent the wave paths resulting from the reflections of the original wave from the surround and the VC. The red lines represent (some of) the additional reflections/transmissions due to the Enable pattern. I won't bother going into any arguments as to why the imaginary sources associated with the enable generated reflections/transmission must be much lower in amplitude than those associated with the original waves other than to say that it should be obvious that if there were of significant magnitude then the measured frequency response of the driver would necessarily be very different. I'm more than happy to go into this if someone wants to honestly discuss it, but I won't engage hand waving arguments as to why it ain't so.
john k... said:
It takes a bit of studying the charts, but I think I see what it indicates. If I'm not mistaken, the enabl application points (or any material added) create an increased number of reflected energy points, as represented by the red lines. Since only some of the energy is reflected at those points, the remaining energy continues to the next reflection point, either the surround or the voice coil, depending on the direction of the energy at that time.
In short and as it appears to me, at least, there is more "noise", so-to-speak, in that there is more of a random nature of the emission of energy from the cone due to the inhomogeneities introduced into the diaphragm.
So I suppose that any conclusion as to the ultimate changes in perception will depend on how much any existing resonances associated with the surround and/or voice coil reflections are altered (shifted, increased or decreased) coupled with any new resonances created by the enabl application itself.
Dave
Thanks for the illustrations John.
I understand what you're saying DLR, and can see the potential for added noise if there are added reflections in the cone material, or even just simply turbulence to those waves due to the EnABL blocks.
But is it not also possible that the EnABL is disrupting the wave ping pong'ing between the VC and the surround (which I'll call a unwanted hysterisis) on the cone material and damping it with the EnABL pattern blocks?
In any event, both these examples are in and/or on the surface of the cone material and not in the air coming off the cone, in which case boundary layer does not even come into play. At least not to my knowledge on the topic of fluid dynamics.
Cheers
I understand what you're saying DLR, and can see the potential for added noise if there are added reflections in the cone material, or even just simply turbulence to those waves due to the EnABL blocks.
But is it not also possible that the EnABL is disrupting the wave ping pong'ing between the VC and the surround (which I'll call a unwanted hysterisis) on the cone material and damping it with the EnABL pattern blocks?
In any event, both these examples are in and/or on the surface of the cone material and not in the air coming off the cone, in which case boundary layer does not even come into play. At least not to my knowledge on the topic of fluid dynamics.
Cheers
A stone in the bush: if the pattern disrupts wave propagation to the extent that some degree of ramdomness results and considering the ear/brain being much more sensitive to patterns than to randomness, could this account to some degree for the perception of "cleaner" sound?
Or has this thought been offered already?
One must keep in mind that these patterns are reported to be successful only if applied in some rather specific ways. I'm not necessarily offering a parallell, but in a DML (NXT radiator) application of the driving force has to be rather specifically located for the chaotic standing wave behaviour to emerge.
More far fetched: what about emergent phenomena? (This is a long shot but hey, I saw the word "emerge"..)
Or has this thought been offered already?
One must keep in mind that these patterns are reported to be successful only if applied in some rather specific ways. I'm not necessarily offering a parallell, but in a DML (NXT radiator) application of the driving force has to be rather specifically located for the chaotic standing wave behaviour to emerge.
More far fetched: what about emergent phenomena? (This is a long shot but hey, I saw the word "emerge"..)
"Just for clarity, which "above" are you referring to? Jon Ver Halen did a set of tests on treated and untreated Lowther PM6A drivers. The ones brought to the last RMAF show for the ad hoc comparison. They do have an extremely similar cone structure, with like materials."
I was referring to my post is on page #258, in which I reported doing my own independent review of Limono's Enabled Lowther DX4s.
As an update to my post, Limono came over to my house and did some listening with his Enabled Lowther DX4 drivers. He confirmed that his drivers did sound smoother at my house being played in my system. We then switched in his amps, and the sound did change to be more strident. His amps are somewhat more "transparent" than mine, and slightly more dynamic.
I have a series of changes that I plan on making to my amps to improve their transparency, so the question is when I do those changes, would my amps start to be more strident like Limono's, or would they achieve the transparency without the stridency?
Anyways, after a lot more listening, I am more convinced that the Enable treatment is very positive for Lowther DX4 drivers. At some point in the future, I will likely take steps to add the Enable treatment.
Retsel
I was referring to my post is on page #258, in which I reported doing my own independent review of Limono's Enabled Lowther DX4s.
As an update to my post, Limono came over to my house and did some listening with his Enabled Lowther DX4 drivers. He confirmed that his drivers did sound smoother at my house being played in my system. We then switched in his amps, and the sound did change to be more strident. His amps are somewhat more "transparent" than mine, and slightly more dynamic.
I have a series of changes that I plan on making to my amps to improve their transparency, so the question is when I do those changes, would my amps start to be more strident like Limono's, or would they achieve the transparency without the stridency?
Anyways, after a lot more listening, I am more convinced that the Enable treatment is very positive for Lowther DX4 drivers. At some point in the future, I will likely take steps to add the Enable treatment.
Retsel
John K,
I am completely in agreement with what you have provided. This is exactly what my mental model provides me with. In a standard modeling such as this, the application of the patterns should only provide an even greater time smear to the longitudinal time train. The added mass should also provide a modifier to these reflections, though I am not entirely sure I have a correct mental model for this process.
In addition, the angle of incidence of the cone, with respect to a point of reception of the time train and the longitudinal center line of the voice coil, should further smear the longitudinal emission of these reflected transverse waves. That because they are creating the smear by producing new longitudinal waves in the air, at the same frequency, but later in time.
Please carry on.
Bud
I am completely in agreement with what you have provided. This is exactly what my mental model provides me with. In a standard modeling such as this, the application of the patterns should only provide an even greater time smear to the longitudinal time train. The added mass should also provide a modifier to these reflections, though I am not entirely sure I have a correct mental model for this process.
In addition, the angle of incidence of the cone, with respect to a point of reception of the time train and the longitudinal center line of the voice coil, should further smear the longitudinal emission of these reflected transverse waves. That because they are creating the smear by producing new longitudinal waves in the air, at the same frequency, but later in time.
Please carry on.
Bud
As I understand it ron will be looking at cone surface velocity. May I ask for some details? At what points on the cone will data be taken? What is that data expected to represent? Please Ron, don't read this as anything negative. I just interested in the details of what you are expected to do
Q:What will be the stimulus?
A: signal generator, both sine and square wave at varing frequencies
Q:
At what points on the cone will data be taken?
A: across the cone in a horozinal plane in any place that does not have a shadow from the wizzer in .001" increments
Q: What is that data expected to represent?
A: a control data vrs a question data
Many times i have no idea in tests like these of how to procede until i have basic data and can stand back and examine.
1. Define the energies at points.(A)
2. Look for changes in the energies.(A/B)
3. If there is no change in energies then look for alternate tests.
4. If there is a change in energies then define the actions based on the test results.
5.If there is a change in energies at different points at different frequencies then define the actions.
Its my belief (and thats all) that if there is an acton happening it will occur at a mid point between the defractors/deflectors/whatever and it will be a very low level amplitude signal that will increase/decrease with the applied change in frequency. If its a mass effect the BW of the energies affected will be slightly greater. Of course i have been wrong before. I hate assumptions because there are outside or non considered influencies that occur. And i have been bitten in the butt by assumptions.
ron
More far fetched: what about emergent phenomena?
Thats just another way of stating" i dont know".
As for ron's little poke, "We can teach or we can do." which I took light heartedly
Thanks John. The reason i put my name as ron instead of Ron( i was asked several times) is i am a very humble person. I have learned to never overstate but just to explain the facts.
Q:What will be the stimulus?
A: signal generator, both sine and square wave at varing frequencies
Q:
At what points on the cone will data be taken?
A: across the cone in a horozinal plane in any place that does not have a shadow from the wizzer in .001" increments
Q: What is that data expected to represent?
A: a control data vrs a question data
Many times i have no idea in tests like these of how to procede until i have basic data and can stand back and examine.
1. Define the energies at points.(A)
2. Look for changes in the energies.(A/B)
3. If there is no change in energies then look for alternate tests.
4. If there is a change in energies then define the actions based on the test results.
5.If there is a change in energies at different points at different frequencies then define the actions.
Its my belief (and thats all) that if there is an acton happening it will occur at a mid point between the defractors/deflectors/whatever and it will be a very low level amplitude signal that will increase/decrease with the applied change in frequency. If its a mass effect the BW of the energies affected will be slightly greater. Of course i have been wrong before. I hate assumptions because there are outside or non considered influencies that occur. And i have been bitten in the butt by assumptions.
ron
More far fetched: what about emergent phenomena?
Thats just another way of stating" i dont know".
As for ron's little poke, "We can teach or we can do." which I took light heartedly
Thanks John. The reason i put my name as ron instead of Ron( i was asked several times) is i am a very humble person. I have learned to never overstate but just to explain the facts.
BudP said:
Having considered John's presentation a bit more, it looks very different to me. The frequencies are not the same and later in time. They cannot be. The frequencies are a function of the time delays for the wave as it comes in contact with any inhomogeneities. The time delays determine the frequencies.
The addition of the pattern creates inhomogeneous points earlier in time rather than later since the initial transverse wave normally does not reflect until it arrives at the surround. It now arrives at the pattern earlier in time, both partially reflecting and partially creating a compression wave in the air at any earlier time. This will create reflections that result in higher frequency resonances due to the shorter time interval. The lower frequency resonance related to the surround may be reduced due to the energy that is diverted into the resonances at the pattern.
Essentially, without there being any actual damping due to the pattern, it's primarily an alteration of the resonances. Those related to the surround are reduced by the amount now associated with the pattern. There are new ones associated with the pattern (since conservation of energy says that the energy not damped has to go somewhere). These new ones are higher in frequency due to the shorter distance from the voice coil to the pattern and the very short distance from the surround back to the pattern. Any energy reflected by the surround interacts with the pattern on its way back to the voice coil. This distance is very short, therefore the resonances associated with it will be much higher in frequency.
The same situation exists with a pattern close to the voice coil. The distance is very short. All energy in the initial transverse wave first encounters a pattern close by, so the resonances associated with it will be stronger, but high in frequency due to the short distance.
The measurements presented correlate fairly well with this. The pre-existing resonances seem to be reduced to varying degrees, but newer ones are introduced, almost all higher in frequency. It's a classic mass/damping/stiffening situation.
Dave
dlr,
I agree with your further analysis and have amended my mental model of standard applied physics to include it. There will be numerous additional resonances arising due to the new travel lengths and further alterations due to the effects of mass upon the transverse waves passing through the patterns.
Bud
I agree with your further analysis and have amended my mental model of standard applied physics to include it. There will be numerous additional resonances arising due to the new travel lengths and further alterations due to the effects of mass upon the transverse waves passing through the patterns.
Bud
Can you use your machine to look at a square wave passing by, out at the outer 1/3 or so of the main cone? Can you repeatedly introduce just one pulse at a time, and over a period of time, look at the initial wave, and the reflections of that wave on an untreated and EnABL'd driver? I would ask for the inner 1/3 too, but I don't see how you could get in there. I want to find out how long this initial transverse wave rings
Yes. The "machine" is nothing more than an acoustically dead enclosure(designed it myself) that transverses over the cone in a horz plane. It can use either square or sine waves, but both will be examined. I am not going to introduce a wave , but allow the natural response from the driver be evaluated.
ron
(yall guys type too much)
Yes. The "machine" is nothing more than an acoustically dead enclosure(designed it myself) that transverses over the cone in a horz plane. It can use either square or sine waves, but both will be examined. I am not going to introduce a wave , but allow the natural response from the driver be evaluated.
ron
(yall guys type too much)
Quote:
Thats just another way of stating" i dont know".
Not clear about your reply. Emergent phenomena occur in open systems with some measure of chaotic behaviour. A local reduction in entropy.
I hope that helps.
Or, if you're stating the obvious (i.e. I don't know - that's why I'm asking with all the apologies) I must assume you are trying to discourage either speculative posts or my posting. If that's the case I'll certainly oblige.
Thats just another way of stating" i dont know".
Not clear about your reply. Emergent phenomena occur in open systems with some measure of chaotic behaviour. A local reduction in entropy.
I hope that helps.
Or, if you're stating the obvious (i.e. I don't know - that's why I'm asking with all the apologies) I must assume you are trying to discourage either speculative posts or my posting. If that's the case I'll certainly oblige.
dlr
If what you say is correct re higher frequency resonances being produced, how would that impact the perceived sound? I'm hoping that some measure of these resonances would be transferred to a range where they're inaudible. Is that what you're saying? Do you think that the magnitude of the effects so produced could account for reported effects of EnABL?
If what you say is correct re higher frequency resonances being produced, how would that impact the perceived sound? I'm hoping that some measure of these resonances would be transferred to a range where they're inaudible. Is that what you're saying? Do you think that the magnitude of the effects so produced could account for reported effects of EnABL?
dlr said:
I guess the whole problem I have in understanding this, is "how" the blocks actually reflect back the wave coming from the voice coil. I mean, the EnABL blocks are a small (in height) surface, and their mass is small (?).
How much of the initial wave could it possibly reflect? Wouldn't it be more a damper than a reflector?
Could it possibly be a kind of diffusor for the waves coming from the voice coil, causing a kind of diffuse turbulence, that when met by the returning (earlier) waves from the surround, cause a cancellation effect when they collide? Kind of like what a primitive root diffusor does with sound waves in room acoustics.
Maybe the answers are right here in this later part of your post??
Maybe it's too late in the day for me to see this clearly now...
Cheers
Daygloworange said:
That is the correct question to ask. But this isn’t a matter of height of the pattern. This is about the transverse waves in the cone. They could potentially be reflected because the effective cone properties change at the enable patters. A change in effective density, or stiffness would mean that the wave propagation through this region would have to be different. This would result in some type of reflection back from where the wave came from. From all the evidence we have the answer is that very little of the energy is reflected by the pattern: If the pattern reflected a significant portion of the energy then the wave from the VC would never be able to enter the cone proper. If some how the wave got past the inner pattern and was reflected back from the outer layer then very little energy would reach and be dissipated in the surround. If the wave passed through the outer pattern with little reflection back into the cone, and then the wave reflected from the surround was somehow blocked form re-entering the cone at the outer layer then the cone proper would be void of standing waves, and the waves trapped between the outer pattern and the surround would be rapidly dissipated by the surround. The thing is that the pattern can not behave as a "check valve" because waves don't carry history with them in the sense that they don't know where the came from and they don't see what is ahead of them. Whether they hit the pattern from the left or right they see the same discontinuity in properties and react the same way. All of these effects would result in significant differences in the frequency response, particularly with regard to the resonances observed at breakup.
One other comment regarding the drivers which have been treated with subjective success, specifically the Lowther and the Fostex drivers which have been tested. It intrigues me that these drivers generally have pretty irregular frequency response to start with. It almost doesn't surprise me that this (or maybe any treatment) would result in a change what would be subjectively considered an improvement. None of these drivers come close to the accuracy of the MG10 for which I posted test data.
Anyway, I'm working on something else that may take a while.
Also, another reason I decided to reject the offer to listen is that I don't want my objective think derailed by a subjective observation. I don't want to be caught up trying to figure out what is the cause of what ever I might hear. I rather spend the time trying to understand the mechanism behind how a change might occur.
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