Graham Maynard said:
I wanna tell you how its gonna be
Youre gonna give your love to me
I'm gonna love you night and day
Love is love and not fade away
How can I say what I said about enable? Because I understand wave propagation. Acoustic waves are a linear phenomena which means they behave the same indipendent of amplitude. If a pebbel in the road doesn't effect a go cart why would you expect it to effect a Mack truck?
Now if you are suggesting that nonlinear effect enter the picture then we need to consider how they enter. I'll discuss that later in all its mathematical glory which few will understand, but for now consider that if we look at a driver like a Fostex 127 radiating 110dB at 1k Hz then the peak cone velocity would be on the order of 1 ft/sec. At those velocities the nonlinear terms remain insignificant.
For completness:
Bud's double ring 8" enable pattern applied to a flat baffle, MG10 centered with mic flush mounted 1" outside the rings. White = no rings. Yellow = double segmented rings, 0.0035" high. Brown = double segmented rings, double tap thichness, 0.0071" high.
Oh, one other thing. The point was raised about an impusew being a short duration signal. But remember these impulses are derived from an MLS singal which starts and ends with a duratuion of approximately 0.07 sec. FWIW, I also tested with a pure impulse. Same resullt.
Bud's double ring 8" enable pattern applied to a flat baffle, MG10 centered with mic flush mounted 1" outside the rings. White = no rings. Yellow = double segmented rings, 0.0035" high. Brown = double segmented rings, double tap thichness, 0.0071" high.
An externally hosted image should be here but it was not working when we last tested it.
Oh, one other thing. The point was raised about an impusew being a short duration signal. But remember these impulses are derived from an MLS singal which starts and ends with a duratuion of approximately 0.07 sec. FWIW, I also tested with a pure impulse. Same resullt.
Hmmm......
So the objective standpoint at the moment is ?
Ignoring the "conformal" coating as it is already well known and
accepted cone treatment (but preferably both sides of the cone) :
It seems the EnABL patterns on solid surfaces have no significant
effect and it therefore follows this also true of EnABL patterns on
non-absorbing cones where the added mass is not significant.
Seems entirely plausible to me (and my initial standpoint) .......
Absorbing cones are somewhat more complex as you can be
changing the local properties of the cone medium, presumably
this depends on the cone type and the application method.
/sreten.
So the objective standpoint at the moment is ?
Ignoring the "conformal" coating as it is already well known and
accepted cone treatment (but preferably both sides of the cone) :
It seems the EnABL patterns on solid surfaces have no significant
effect and it therefore follows this also true of EnABL patterns on
non-absorbing cones where the added mass is not significant.
Seems entirely plausible to me (and my initial standpoint) .......
Absorbing cones are somewhat more complex as you can be
changing the local properties of the cone medium, presumably
this depends on the cone type and the application method.
/sreten.
Hi John,
I simply cannot understand your attitude in this regard;-
>> How can I say what I said about enable? Because I understand wave propagation. Acoustic waves are a linear phenomena which means they behave the same indipendent of amplitude. <<
I suggest that you are then failing to consider that a conicular or dome driver does not radiate coincidentally wrt observer from all points, and thus there is an 'air space' region in which radiated components add or subtract prior to establishing a propagating wave through room air in any direction, such that pressure /velocity gradients change position over the driver surface with frequency and modify radiation prior to propagation.
What happens prior to a wave being propagated to an observer is NOT via linear radiation, this due to physical pressure /velocity contour positions changing between cone and effective launch plane at any frequency.
Your test ring in Post#123 was knowingly postioned beyond the region of pressure /velocity change with frequency.
Please don't assume I am a proponent of EnABL, I have never claimed this.
It is just that your arrogant 'I know what I am writing about' stance has still done nothing to directly disprove or explain any EnABL effect either !
Why not place that EnABL test ring on the driver and re-do the Post#123 test ?
Treat half the cone perimeter only and then rotate by 180 degrees with the mic in the baffle.
Knowledge and understanding are far from being recounted as if the same attribute.
Cheers ........... Graham.
I simply cannot understand your attitude in this regard;-
>> How can I say what I said about enable? Because I understand wave propagation. Acoustic waves are a linear phenomena which means they behave the same indipendent of amplitude. <<
I suggest that you are then failing to consider that a conicular or dome driver does not radiate coincidentally wrt observer from all points, and thus there is an 'air space' region in which radiated components add or subtract prior to establishing a propagating wave through room air in any direction, such that pressure /velocity gradients change position over the driver surface with frequency and modify radiation prior to propagation.
What happens prior to a wave being propagated to an observer is NOT via linear radiation, this due to physical pressure /velocity contour positions changing between cone and effective launch plane at any frequency.
Your test ring in Post#123 was knowingly postioned beyond the region of pressure /velocity change with frequency.
Please don't assume I am a proponent of EnABL, I have never claimed this.
It is just that your arrogant 'I know what I am writing about' stance has still done nothing to directly disprove or explain any EnABL effect either !
Why not place that EnABL test ring on the driver and re-do the Post#123 test ?
Treat half the cone perimeter only and then rotate by 180 degrees with the mic in the baffle.
Knowledge and understanding are far from being recounted as if the same attribute.
Cheers ........... Graham.
conicular
Or did u mean frusto-conicular?
"I suggest that you are then failing to consider that a conicular or dome driver does not radiate coincidentally wrt observer from all points, and thus there is an 'air space' region in which radiated components add or subtract prior to establishing a propagating wave through room air in any direction, such that pressure /velocity gradients change position over the driver surface with frequency and modify radiation prior to propagation."
with good reason, no doubt...
Or did u mean frusto-conicular?
"I suggest that you are then failing to consider that a conicular or dome driver does not radiate coincidentally wrt observer from all points, and thus there is an 'air space' region in which radiated components add or subtract prior to establishing a propagating wave through room air in any direction, such that pressure /velocity gradients change position over the driver surface with frequency and modify radiation prior to propagation."
with good reason, no doubt...
Attachments
Hi John,
Another excellent test showing that a concentric driver ring has insignificant effect when on the surface of a baffle. Bud stated he does not do this because he does not recall any advantage from same.
I particularly appreciate the way in which you are trying to isolate any mass /cone effect from any possible air /shape effect by testing the pattern away from the cone.
Yet it seems that specified 'on-cone', baffle edge and port treatments are still not being examined, so what about placing this pattern on a radiating aperture edge with the driver behind a baffle ?
This would not have any mass effect yet act within a cone driven region of wave development.
It would also be interesting to see a laser CT of wave development within a conicular aperture.
Cheers .......... Graham.
PS. I did not read Post#173 beyond your words 'pretty thick' being addressed to other posters here.
Another excellent test showing that a concentric driver ring has insignificant effect when on the surface of a baffle. Bud stated he does not do this because he does not recall any advantage from same.
I particularly appreciate the way in which you are trying to isolate any mass /cone effect from any possible air /shape effect by testing the pattern away from the cone.
Yet it seems that specified 'on-cone', baffle edge and port treatments are still not being examined, so what about placing this pattern on a radiating aperture edge with the driver behind a baffle ?
This would not have any mass effect yet act within a cone driven region of wave development.
It would also be interesting to see a laser CT of wave development within a conicular aperture.
Cheers .......... Graham.
PS. I did not read Post#173 beyond your words 'pretty thick' being addressed to other posters here.
soongsc said:
George,
Maybe I am missing something. But if the enable blocks on the baffle didn't change the signal passing over them in any way measureable by the impulse measurement John did, I am not sure what you expect to see that would be different when that same unchanged sound is reflected from the baffle edge and measured by the same technique.
Kind regards,
Dennis
Hi John,
You wrote;-
>> To the contrary. Everything you are referring to still falls within the realm of linear behavior. <<
Thank you for responding in this regard.
Linear related to amplitude - yes; but all components linear in music time wrt the eventually propagating waveform ?
Not trying to be funny - hope you get my drift - and whether EnABL might modify observed waveform linearity in time.
I'm with Soongsc, and would love to see a pair of edge related measurements with appropriately sized pattern, whether at edge of baffle, driver aperture or port, none of which could affect the cone mass distribution.
Cheers ....... Graham.
You wrote;-
>> To the contrary. Everything you are referring to still falls within the realm of linear behavior. <<
Thank you for responding in this regard.
Linear related to amplitude - yes; but all components linear in music time wrt the eventually propagating waveform ?
Not trying to be funny - hope you get my drift - and whether EnABL might modify observed waveform linearity in time.
I'm with Soongsc, and would love to see a pair of edge related measurements with appropriately sized pattern, whether at edge of baffle, driver aperture or port, none of which could affect the cone mass distribution.
Cheers ....... Graham.
djarchow said:
Hmm, isn't there a measurable change? That is is or is not meaningful, well thats a separate issue.
Moreover (as I believe stated before), the impulse response also presents diffraction effects (..depending of course on the baffle and the test). However,
The impulse response only displays the linear behavior on one axis. The question then is: is a look at one axis sufficient?
When considering this question, remember that its likely that most listener's will not listen to their speakers on the primary axis.
Graham Maynard said:
Linearity includes time and phase.. and of course an impulse response includes both.
What it isn't showing however is *dynamic* behavior (..well at least not beyond a very simplified perspective).
I might be missing somthing as well, but it seems much more easier to measure at a location that captures both original impulse and diffraction impulse by using an existing speaker, why go through all the effort to measure from a baffle and flush mount the mic? If the diffraction impulse cannot be measured, then that means the pattern effects cannot be measured either. However, if we can look at the main impulse and the diffraction impulse, things are brought into perspective.djarchow said:
One thing to also consider is look at the SPL of the impulses before and after the rings. What seemingly is very small in the impulse might show more differences when looking at the frequency composition.
ScottG said:
Hmm, isn't there a measurable change? That is is or is not meaningful, well thats a separate issue.
Moreover (as I believe stated before), the impulse response also presents diffraction effects (..depending of course on the baffle and the test). However,
The impulse response only displays the linear behavior on one axis. The question then is: is a look at one axis sufficient?
When considering this question, remember that its likely that most listener's will not listen to their speakers on the primary axis.
As John mentioned the time scale of the graph and the location of the patterns, I do not get the impression that the graph contains the edge diffraction.
Linearity includes time and phase.. and of course an impulse response includes both.
What it isn't showing however is *dynamic* behavior (..well at least not beyond a very simplified perspective).
Hi Scott,
I see that Snoogsc has highlighted your words from your Post#193 without explaining why.
In this post you posed a 'think about it' question.;-
>> The impulse response only displays the linear behavior on one axis. The question then is: is a look at one axis sufficient? <<
Surely anything which modifies an amplitude or frequency or phase or group delay response is going to generate a resultant observable as an amplitude response variation in time, and John L's EnABL baffle surface ring tests do have the required second axis - Time ?
Thus all of these aspects must cover the dynamic response too.
There must be a specific time delay related to any possible first change induced by a ring or pattern etc., and therefore any waveform modification must be first apparent after that specific time delay, and a concentric ring wrt a circular driver would have a more recordable effect wrt that driver than to any baffle edge induced effect.
What an impulse test cannot show is any change related to the final development of highly resonant modes, but it would still reveal a time delayed initial change which might induce that same resonance.
I agree that an on-axis response cannot tell the whole story either, but John has shown us that he can accurately resolve to low levels within a waveform, and if *nothing* shows down to say minus 50dB., then that result must be definitive.
An axial microphone which is too close (short time axis) can however cancel out some of the audible beaming effects which are due to driver size and shape and audible at a listening position. We only have to place our own ears closer to a cone driver in order to observe this change.
To retain a short time axis, maybe a close microphone is better positioned where it might detect any change due to edge patterns, as if the edge were the source.
Cheers ........... Graham.
I see that Snoogsc has highlighted your words from your Post#193 without explaining why.
In this post you posed a 'think about it' question.;-
>> The impulse response only displays the linear behavior on one axis. The question then is: is a look at one axis sufficient? <<
Surely anything which modifies an amplitude or frequency or phase or group delay response is going to generate a resultant observable as an amplitude response variation in time, and John L's EnABL baffle surface ring tests do have the required second axis - Time ?
Thus all of these aspects must cover the dynamic response too.
There must be a specific time delay related to any possible first change induced by a ring or pattern etc., and therefore any waveform modification must be first apparent after that specific time delay, and a concentric ring wrt a circular driver would have a more recordable effect wrt that driver than to any baffle edge induced effect.
What an impulse test cannot show is any change related to the final development of highly resonant modes, but it would still reveal a time delayed initial change which might induce that same resonance.
I agree that an on-axis response cannot tell the whole story either, but John has shown us that he can accurately resolve to low levels within a waveform, and if *nothing* shows down to say minus 50dB., then that result must be definitive.
An axial microphone which is too close (short time axis) can however cancel out some of the audible beaming effects which are due to driver size and shape and audible at a listening position. We only have to place our own ears closer to a cone driver in order to observe this change.
To retain a short time axis, maybe a close microphone is better positioned where it might detect any change due to edge patterns, as if the edge were the source.
Cheers ........... Graham.
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