back in the hole, you varmit!
Bud,
Flailing with the knowledge that things will become simple in the end...I offer pure speculation...excite the untreated driver with pure tones (single frequency)...or sweep frequencies slowly so that it is discovered where the resonances within the system exist. I think there will be sidebands, sympathetic to the driving tone. Those sidebands are indicators of the unwanted hash that EnABL has been found to cure. With experience, it may become possible to prescribe treatment based upon the frequencies that excite the fricative stuff.
A question: Do you hear the fricative hash more with women singers? I think I do, though without sharing the same listening experience we can't be sure. I hear that stuff more with some singers. Patty Griffin comes to mind most recently.
Bud,
Flailing with the knowledge that things will become simple in the end...I offer pure speculation...excite the untreated driver with pure tones (single frequency)...or sweep frequencies slowly so that it is discovered where the resonances within the system exist. I think there will be sidebands, sympathetic to the driving tone. Those sidebands are indicators of the unwanted hash that EnABL has been found to cure. With experience, it may become possible to prescribe treatment based upon the frequencies that excite the fricative stuff.
A question: Do you hear the fricative hash more with women singers? I think I do, though without sharing the same listening experience we can't be sure. I hear that stuff more with some singers. Patty Griffin comes to mind most recently.
Re: back in the hole, you varmit!
My hypotheses is that this is part of man's basic survival mechanism - bred into us over thousands of generations - as the result of needing to be aware of territory encroachment by mother in laws. 😉
Ed LaFontaine said:
My hypotheses is that this is part of man's basic survival mechanism - bred into us over thousands of generations - as the result of needing to be aware of territory encroachment by mother in laws. 😉
BudP said:
I'm not sure I understand his description. Swept sines in anything less than a full anechoic chamber are not reliable due to room reflections.
In any case, it's a simple matter to take two measurements (both done identically, of course) and normalize one to the other and see only the difference between the two. As for other points, I've got exactly this kind of presentation of data at my site. I believe the Insignia woofer mod page has this.
Those two showing the direct comparison I made of four different resonances affected, three reduce, one created that resulted in a dip.
They don't challenge the Hilbert Transform, as John K pointed out there wasn't a valid assessment of the results and no corrections were made for any possible excess-delay. The relationship between a raw driver and its phase response is not altered by any damping treatment. If the driver is minimum-phase, the HBT will hold, no exceptions. In all the years I've measured and modeled drivers I (and others) have never found a driver that was not minimum-phase up to and into the breakup.
I seriously doubt that even a full range driver's response is not minimum-phase into the breakup. I've measured then modeled the response of a 10" driver with significant breakup to 20KHz and was able to create the model properly so that it showed excellent correlation between measured and generated (HBT) phase. There are a couple of key issues in creating a model correctly that some may not be aware of that affect the HBT. Usually when the HBT from a model does not match measured phase there was some error in the model. The model and especially the lowpass Fc is critical.
At times to get the best model, I've had to go back to CALSOD, one of my favorite CAD programs that was first available back in the late 80's. Even though its an old DOS program, it actually has some features not available in just about all of the current CAD packages and can provide detail in a model not possible in newer GUI CAD software. It's more tedious, but it's more detailed if one takes the time to go to that detail. Most folks today just want "point and click".
Dave
And this is what we see in CSD plots as a result. I am curious as to what you used to reconstruct the 3D actions of the EnAble effect?ronc said:
dlr,
Dave, do you have the time to walk me through what this sentence means?
How are these corrections for excess delay determined? And what does a "valid assessment" consist of? Maybe John K can chime in. Nor am I at all certain what "minimum phase" means nor how it is determined within a CSD plot.
From experience with mid/hi frequency drivers of various sorts, their reconstruction of transient rich information, like violin plucks, glass chime strikes and drum head strikes, has the "time train" information corrected from application of EnABL. Is this correction rearrangement related in any way to phase?
Again this is a listening event, but I have no small amount of orchestral experience, from the Tuba section and so have many hours of hearing these sorts of devices live, often next to me and about as often, 10 to 15 feet away.
To date the only driver I have heard that was correct sounding through a big portion of this frequency band, without EnABL, was an EV TH 350 horn tweeter.
Interestingly it sounded just like the control TH350, before EnABLing and after. In either case they had the correct peaks and edges, in the correct places, within the various notes. EnABL caused no improvement, and yet the amount of mass applied to the phenolic dome and all internal compression surfaces seemingly caused no degradation either. I only treated the driver at the insistence of it's owner.
I suppose the thing to take from this is that correctly designed compression drivers do not have the problems that EnABL is designed to diminish. Alexsander from RAAL claims his ribbons will not show any differences either and he is probably correct.
Bud
Dave, do you have the time to walk me through what this sentence means?
How are these corrections for excess delay determined? And what does a "valid assessment" consist of? Maybe John K can chime in. Nor am I at all certain what "minimum phase" means nor how it is determined within a CSD plot.
From experience with mid/hi frequency drivers of various sorts, their reconstruction of transient rich information, like violin plucks, glass chime strikes and drum head strikes, has the "time train" information corrected from application of EnABL. Is this correction rearrangement related in any way to phase?
Again this is a listening event, but I have no small amount of orchestral experience, from the Tuba section and so have many hours of hearing these sorts of devices live, often next to me and about as often, 10 to 15 feet away.
To date the only driver I have heard that was correct sounding through a big portion of this frequency band, without EnABL, was an EV TH 350 horn tweeter.
Interestingly it sounded just like the control TH350, before EnABLing and after. In either case they had the correct peaks and edges, in the correct places, within the various notes. EnABL caused no improvement, and yet the amount of mass applied to the phenolic dome and all internal compression surfaces seemingly caused no degradation either. I only treated the driver at the insistence of it's owner.
I suppose the thing to take from this is that correctly designed compression drivers do not have the problems that EnABL is designed to diminish. Alexsander from RAAL claims his ribbons will not show any differences either and he is probably correct.
Bud
soongsc said:
Ron uses a custom version of some mainframe class fluid dynamics software that helps him keep the USA's petrochemicals flowing (or something like that...)
dave
Hi Dave,
My test suggestion in Post#1665 is for continuos/single/burst single sine frequency nulling examination, not swept.
________________________________________________
If there are steady state induced effects due to surface waves which EnABL can reduce, then I would expect the before/after differences to show more clearly upon the nulled waveform.
I would also expect the nulling amplitude and phase adjustment to be different, which also would prove that a change has taken place.
When the sudden start-up of a sine energises air motion in front of the cone (higher frequency components due to sudden start-up) and there is dynamic leading edge error wrt the electric waveform drive due to series voice coil/cone impedance, this again would show driver weaknesses, but would also leave the 'view' clearer for much closer inspection of EnABL results because the transduced fundamental should be capable of being nulled by maybe 20 to 40 dB (which would of course also increase relative viewing levels of non-anechoic room interferences).
Both tests could tie in with Ed's suggestion in Post#1672; for many pieces of test equipment could observe the resultant nulled mic/sine output.
_______________________________________________
A couple of other points arisin from recent discussions.
(1) Do microphone diaphragms need EnABL ?
Dome types tend to be smaller in diameter than the shortest air wavelength they transduce efficiently; also they are driven by establed relatively far field air pressure variations rather than creating localised pressure changes which then propagate as waves.
________________________________________________
(2) Jeepers - need a torch to go look down that tunnel -
I've forgotten whilst writing the above.
Annoying, but typical of me, so I just gotta laugh. (Can't beat pen and paper eh!)
Cheers ........... Graham.
My test suggestion in Post#1665 is for continuos/single/burst single sine frequency nulling examination, not swept.
________________________________________________
If there are steady state induced effects due to surface waves which EnABL can reduce, then I would expect the before/after differences to show more clearly upon the nulled waveform.
I would also expect the nulling amplitude and phase adjustment to be different, which also would prove that a change has taken place.
When the sudden start-up of a sine energises air motion in front of the cone (higher frequency components due to sudden start-up) and there is dynamic leading edge error wrt the electric waveform drive due to series voice coil/cone impedance, this again would show driver weaknesses, but would also leave the 'view' clearer for much closer inspection of EnABL results because the transduced fundamental should be capable of being nulled by maybe 20 to 40 dB (which would of course also increase relative viewing levels of non-anechoic room interferences).
Both tests could tie in with Ed's suggestion in Post#1672; for many pieces of test equipment could observe the resultant nulled mic/sine output.
_______________________________________________
A couple of other points arisin from recent discussions.
(1) Do microphone diaphragms need EnABL ?
Dome types tend to be smaller in diameter than the shortest air wavelength they transduce efficiently; also they are driven by establed relatively far field air pressure variations rather than creating localised pressure changes which then propagate as waves.
________________________________________________
(2) Jeepers - need a torch to go look down that tunnel -
I've forgotten whilst writing the above.
Annoying, but typical of me, so I just gotta laugh. (Can't beat pen and paper eh!)
Cheers ........... Graham.
Well, I wish I had my hands on thing like that. Seems like cone dimensions and shapes are critical.planet10 said:
DIYAudio.com is a bastion of sanity compared to youtube but I found a video there showing the drum modes of a piece of paper that was mounted over a loudspeaker. They threw some light powder on the paper and fooled around with SPLs and frequency. I think speaker modes might look a bit different because of the attachment at the inner and outer edges. I can't figure out what they're talking about - something to do with the mysterious structure of the universe - my niece would say, "Whatever!"
The areas with no powder are the modal areas which radiate and thus the powder migrates, shaken away to areas of lesser vibration.
http://www.youtube.com/watch?v=3csi-2Hrzhg&feature=related
The areas with no powder are the modal areas which radiate and thus the powder migrates, shaken away to areas of lesser vibration.
http://www.youtube.com/watch?v=3csi-2Hrzhg&feature=related
OT
They're mindless logic gadgets.
The internet is a big library. But you decide how the catalogue is laid out and go browse in its stacks.
Google advanced search has
Exact phrase - most general there ( may be only one word eg psychoacoustics) - you want lots of hits
With at least one of the word(s) (eg phase) - particular
Get a bunch of hits - (set the thing for at least 30 results per page)
It's not always clear which is general and which is particular - category/subcategory - you can switch them around
Sometimes the filter is useful -Not including (eg secret messages)
at the bottom of results page:
Search within results (eg music) - this is irritating because it only gives ten results
Make sure your browser is using an up to date version of Adobe Reader - mine crashes once in a while so if you have tabs for your browser screen use them because you only lose what's in that tab.
If you get a fabulous combination or search items - a rich vein - be sure you bookmark it so you don't spend an hour trying to recreate the magic moment.
They're mindless logic gadgets.
The internet is a big library. But you decide how the catalogue is laid out and go browse in its stacks.
Google advanced search has
Exact phrase - most general there ( may be only one word eg psychoacoustics) - you want lots of hits
With at least one of the word(s) (eg phase) - particular
Get a bunch of hits - (set the thing for at least 30 results per page)
It's not always clear which is general and which is particular - category/subcategory - you can switch them around
Sometimes the filter is useful -Not including (eg secret messages)
at the bottom of results page:
Search within results (eg music) - this is irritating because it only gives ten results
Make sure your browser is using an up to date version of Adobe Reader - mine crashes once in a while so if you have tabs for your browser screen use them because you only lose what's in that tab.
If you get a fabulous combination or search items - a rich vein - be sure you bookmark it so you don't spend an hour trying to recreate the magic moment.
I really don't want to get back into this thread because it consistenly seems to want to turn what should be a simple problem in to a complex one. Chill out, lay back, put one some music and enjoy.
Just back for a moment - to conjecture/hypothesise a little more about the behaviour of air directly in front of and in near contact with a LS cone.
______________________________________________
Air is elastic; it stores/releases energy during/after compression/rarification.
Compression/rarefaction occurs right in front of the cone, but forces imposed by the cone and against the air are not entirely normal to the motion of that cone, so some storage/release must be converted and thus develop components acting parallel to the cone surface (Bud's vectoring ?).
That energy cannot release during the same time frame wrt the cone and cone excitation *if* it becomes 'gripped' by the cone or reflected at centre or edge.
Thus the energy transfer from cone to air beyond the loudspeaker cannot be wholly pistonic, and the greater the pressure alternation the greater must become the non-pistonic behaviour.
______________________________________________
Maybe the EnABL patterns lead to a loss of 'grip' regarding those parasitically transformed and elastically stored/released energies parallel to the cone surface ?
______________________________________________
I reported before about thin strips of felt improving 'reproduction' when held just above the centre of a cone, but towards the dome/cone join. John (dlr) said - but of course.
However, the material might be absorbing central region energies at higher frequencies which are no longer axial with cone motion, but still impairing the clarity of reproduction because their parallel to cone effect is concentrated in the central region where the reflected pressure peak at the cone centre could lead to parasitic higher frequency radiation.
I still can't remember what the other point was I was going to mention.
Cheers ............ Graham.
______________________________________________
Air is elastic; it stores/releases energy during/after compression/rarification.
Compression/rarefaction occurs right in front of the cone, but forces imposed by the cone and against the air are not entirely normal to the motion of that cone, so some storage/release must be converted and thus develop components acting parallel to the cone surface (Bud's vectoring ?).
That energy cannot release during the same time frame wrt the cone and cone excitation *if* it becomes 'gripped' by the cone or reflected at centre or edge.
Thus the energy transfer from cone to air beyond the loudspeaker cannot be wholly pistonic, and the greater the pressure alternation the greater must become the non-pistonic behaviour.
______________________________________________
Maybe the EnABL patterns lead to a loss of 'grip' regarding those parasitically transformed and elastically stored/released energies parallel to the cone surface ?
______________________________________________
I reported before about thin strips of felt improving 'reproduction' when held just above the centre of a cone, but towards the dome/cone join. John (dlr) said - but of course.
However, the material might be absorbing central region energies at higher frequencies which are no longer axial with cone motion, but still impairing the clarity of reproduction because their parallel to cone effect is concentrated in the central region where the reflected pressure peak at the cone centre could lead to parasitic higher frequency radiation.
I still can't remember what the other point was I was going to mention.
Cheers ............ Graham.
In much the same fashion: One vector component of the acoustic energy, the one parallel to the cones surface, may have a threshold, above which it cannot remain on the cone. I wonder if the EnABL pattern is just enough to "bump" the acoustic energy off the cone?
Graham Maynard said:
I agree with john's statement. Everyone is trying to over-complicate the whole thing. The measurements suggested are fully sufficient. "Nulling examinations" will, I believe, show no more and may leave room for other errors to arise. This sounds like what may have been used prior to modern MLS measurements systems. And once again, these systems are fully capable of measuring changes 30-40db down from nominal if the system is used correctly, even by amateur DIYers. I see no need to try to devise some other way to measure these. It's a non-starter.
All of the discussions about air motion and sudden startup have all been addressed. An impulse encompasses it all. All driver mechano-acoustic impact is fully reflected in the impedance as seen at the driver terminals and therefore fully taken into account in any and all driver measurements, whether they be of impedance, frequency response, distortion, whatever. Implying some kind of unknown impact due to air motion conjecture serves no useful purpose other than to confuse.
Take some standard measurements! There are well established methods and the capability exists to demonstrate the driver transfer function changes (or lack thereof) due to a modification! ALL of the effects can be measured with the systems available. Drivers as acoustic devices are a system. That system encompasses the full electrical/mechanical/acoustic properties. The system output is what we hear and perceive. If there is a change in the system response (no matter any complex interaction between all three), then it MAY be possible to hear it. If there is no change, we will hear no change save for the possibility of the placebo effect. The latter is not insignificant, either. If it is dismissed as a possibility, there can be no confidence in the effort. But I suspect that I'll be taken to task for making that last point. From what I read here, the majority likely dismiss that possibility. Sighted anecdotal reports will always be questioned by anyone with any amount of understanding of test procedures.
As an aside, I still read of the audible improvements of the "Beaks" promoted by one speaker manufacturer and of course there's the plethora of other products that were claimed to have audible properties later disproved, so please consider why there are skeptics in the crowd. Nothing can replace objective observations designed to support the subjective, but that support has to be produced reliably. Negative results have to be reported as well, otherwise its all futile.
There is also the distinct possibility that one driver will show significant effects (full range the most likely I believe) while others will show little. This doesn't invalidate any modifications, rather it simply reflects reality. I have made modifications myself that to my surprise showed essentially no change whatsoever to a driver that showed distinct change by another mod. The tests are to lay bear the facts, nothing more, nothing less.
I have also found in making modifications that the majority of them were detrimental.
The one issue that is relevant for a mic is that any distortion measurements need to be made scuh that the mic that will not be over-driven into its own distortion range. High level distortion tests need extra consideration, but that's part and parcel of proper test techniques.
Dave
Much of this is rather off-topic
Review john's earlier posts, I don't think that I can add more.
It's a standard procedure when dealing with any acoustic measurement. Time is added to/removed from the measurement to correct or adjust the phase shown in the measurement. The basic case is that of removing all excess-phase (linear distance equivalent) from a measurement to present the phase of the driver alone, the driver minimum-phase.
Minimum-phase is essentially the phase at the driver acoustic center. Excess-phase is zero at that point. Any distance away from that theoretical center is excess-phase. The one sticking point is that it is not possible to determine the absolute acoustic center, so it is an approximation and uses the model of the driver (a critical construct) as the basis.
However, two measurements of the same driver can be adjusted without creation of a model because in that case the AC is essentially unchanged.
Everything in the acoustic output of a driver is frequency response magnitude and phase and they are inextricably tied together. If there is a change in one, there is a change in the other. Period.
Hard for me to say much except that drivers can be modified, may or may not show measurable changes, yet if there is a change it may be inaudible. The fact that you didn't hear a change is a classic case of not proving that there wasno change, just that in your case for that instance, you did not hear it. Proving audibility reliably is more difficult, the reason why anecdotal evidence is considered insufficient.
Compression drivers are a whole different breed, I have no experience. But they are designed to produce output in a different manner and don't react in the same way to changes I suspect.
Dave
BudP said:
Review john's earlier posts, I don't think that I can add more.
It's a standard procedure when dealing with any acoustic measurement. Time is added to/removed from the measurement to correct or adjust the phase shown in the measurement. The basic case is that of removing all excess-phase (linear distance equivalent) from a measurement to present the phase of the driver alone, the driver minimum-phase.
Minimum-phase is essentially the phase at the driver acoustic center. Excess-phase is zero at that point. Any distance away from that theoretical center is excess-phase. The one sticking point is that it is not possible to determine the absolute acoustic center, so it is an approximation and uses the model of the driver (a critical construct) as the basis.
However, two measurements of the same driver can be adjusted without creation of a model because in that case the AC is essentially unchanged.
Everything in the acoustic output of a driver is frequency response magnitude and phase and they are inextricably tied together. If there is a change in one, there is a change in the other. Period.
Hard for me to say much except that drivers can be modified, may or may not show measurable changes, yet if there is a change it may be inaudible. The fact that you didn't hear a change is a classic case of not proving that there wasno change, just that in your case for that instance, you did not hear it. Proving audibility reliably is more difficult, the reason why anecdotal evidence is considered insufficient.
Compression drivers are a whole different breed, I have no experience. But they are designed to produce output in a different manner and don't react in the same way to changes I suspect.
Dave
Graham Maynard said:
One clarification. I did not say "but of course" to an improvement. I said that with regard to a change in response. Improvement is a judgement to be made case-by-case. Anything blocking or damping any part of the acoustic output is a change, good or bad. The effect of that change becomes the issue.
Dave
Hi Dave,
You might not have written the exact words I summarised as -'but of course'-, though this is a fair summary of the obvious you covered.
I find it disappointing that you should be so positively negative towards examining for the effects of EnABL by any method not tried with it before -
"It's a non-starter."-
without you explaining why you think there cannot be any benefit from doing so;
as if everything is known and has already been studied.
I am not trying to argue, nor to be awkward, but Ron above in Post#1678 writes well on the topic, so it would be nice to have some objective results.
Cheers ......... Graham.
You might not have written the exact words I summarised as -'but of course'-, though this is a fair summary of the obvious you covered.
I find it disappointing that you should be so positively negative towards examining for the effects of EnABL by any method not tried with it before -
"It's a non-starter."-
without you explaining why you think there cannot be any benefit from doing so;
as if everything is known and has already been studied.
I am not trying to argue, nor to be awkward, but Ron above in Post#1678 writes well on the topic, so it would be nice to have some objective results.
Cheers ......... Graham.
Graham Maynard said:
I say what I say because that's the case insofar as anything that is an obstruction of any kind placed in the acoustic path. Nothing says a priori that the change will be an improvement, but it's guaranteed that a change of some kind will occur. No material is totally acoustically transparent, most materials have significant bandpass/filter characteristics. Therefore: but of course.
There are two issues. One, is there a change and if so what is the impact? Two, if there is a change, what is it's origin?
Item One can be fully examined without devising new measurement schemes, but all focus is on finding some way to bypass the ubiquitous systems used by pretty much the whole industry.
Item Two may be of interest to some, but item One has not yet been undertaken and it's a non-started insofar as empirical results for item One are concerned. Most here seem to want to determine item Two first and spend significant efforts in conjecture and hypothesis about how it works, yet the first step should be step One for which there exists sufficient capability today.
How about some objective results on item One that can be determined well in advance of any attempts at item Two?
In fact, item One has no reliance on any other considerations. Item Two requires that item One be validated insofar as audibility of any change is concerned. Even if item Two were verified beforehand, there's no evidence that item One will therefore support claims of audibility made for item Two.
Dave
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