Hi Sreten,
Can you not see that John K's plot as shown in Posts#336 + #367 is missing on relevant (necessary) data, that being air-density/pressure ?
This is not conjecture, hence my question.
Nor any unwillingness on my part to agree with anyone - OKAY ?
Hi John K,
Given that there can be notable focussing of wave pressure (at for example a cone centre) *without* air flow, is there not going to be a pressure/density modulation which will affect your Energy/Eo ratio plot ?
Cheers ......... Graham.
COMPLAINT TO MODERATOR. Ref POST#378.
Sreten's quite unnecessary remarks about Steve Deckert !
Can you not see that John K's plot as shown in Posts#336 + #367 is missing on relevant (necessary) data, that being air-density/pressure ?
This is not conjecture, hence my question.
Nor any unwillingness on my part to agree with anyone - OKAY ?
Hi John K,
Given that there can be notable focussing of wave pressure (at for example a cone centre) *without* air flow, is there not going to be a pressure/density modulation which will affect your Energy/Eo ratio plot ?
Cheers ......... Graham.
COMPLAINT TO MODERATOR. Ref POST#378.
Sreten's quite unnecessary remarks about Steve Deckert !
Graham Maynard said:
I read only a small part of that page before I came to the same conclusion as Sreten. All one need read to arrive at that is this statement on that page:
"...the ear expects to hear these low frequencies come at it from the sides and arced back to the center".
I use this to support the assessment and veracity of Sreten's point. I think it to be an accurate one, as it does show how using ears alone is fraught with unreliability, much of the basis for the discussion in this thread.
The ear does not "expect" anything with regard to low frequency content. On the contrary, it's a well-researched and established fact that below some frequency, around 85Hz IIRC, maybe a bit lower, no one is capable of detecting the source (direction). That statement alone is symbolic of the writer's "exaggerations" and verbosity, to put it politely. This was in regard to subwoofers that, according to him, must "...reproduce the harmonics of those low frequency's (sic) for at least 8 octaves with high frequency content at background levels.". Subwoofers!
Dave
Sreten,
What I find most annoying about this thread is that some people refuse to help those who are trying to empirically test certain ideas being discussed here, saying that somehow they have to first demonstrate there's a phenomenon that needs to be tested. Well...that's circular reasoning if you're relying on John K's and others theories and testing of those theories which, while they might make sense and have testing to support them, still are simply tests of the theories about mechanisms. Since the theories might be wrong, these tests may disprove the theories but not necessarily the effects of EnABL.
John K has come closest to testing EnABL in a way that would make me feel confident as proof of a theory. I don't know enough about what he did (can't make sense from the posts, much as he, I'm sure, will say I should be able to) to come to that conclusion. I commend him for his hard work and am close to being convinced, at least in theory, of his positions. But I still don't see real EnABL testing, just testing of the theories that have been postulated about it's mechanisms. (FYI, I understand the importance of having a theory to test, but I'm talking here about testing suggestions to help proponents objectively measure what they seem to be hearing - a different kind of testing).
So I think what Alex is asking for makes sense. If you and others were willing to help define the protocols being pursued by proponents that could put this to rest, it would seem to serve your purpose as well as others'. I know you and others think proponents won't believe the results if they don't support what they want to believe, but that idea itself is just a THEORY right now. No one has helped a proponent to develop testing that they want to do, so we don't know how they would respond to results that don't support their subjective listening tests.
Carl
Graham Maynard said:
Hi,
Unnecessary ?
One of my favorites :
PRINCIPLE OF THE DECWARE PHASE GUIDE NOV 2003 by Steve Deckert
http://www.decware.com/newsite/mainmenu.htm?/paper94.htm&intro
He does have a right to free speech and all that, utterly outstanding drivel.
The mk1 phase guide is in fact a Socket from a standard
1/2" drive socket set of a size that fits the front pole piece,
presumably selected by length from different socket sets.
/sreten.Alex from Oz said:
It's all the same. Been said before. Start with an MLS pulse, convert it to an impulse, process the impulse to see frequency response, CSD, burst, step response, etc. I looked at the output of the port in the time and frequency domain. Looking directly at the impulse is actually one of the most sensitive things to look at. Small but obvious differences in an impulse response can represent only a 1/10 dB change in the frequency response. They will never been seen in a CSD plot, or a burst response, etc.
Carlp said:
I have to disagree completely. John's tests do not test a theory, they test for any and all alterations that might occur to a wave passing over any surface object, enabl or any other. Theory means nothing when measuring, it's simply detecting what exists, sampling reality. The mechanism of that change (if any) is immaterial at that point. If there is a change, then the next step would be to try determine the mechanism if there is not one that explains the change. However, if there is no change or the change is insignificant, there is nothing to determine or no need to determine it, respectively, other than as an exercise for the latter.
This latter point is exactly the case here. John showed there to be no measurable change to a wave to more than -60db down. The mechanism is moot at that point.
Next John showed what possible change could be made by an application on the order of enabl. It showed that for audio frequencies it is less than -40db in the power response. This means that on any listening axis, it will be almost non-existent, certainly not audible by any human being. This applies to stationary surfaces and by extension (as he described) to any driver surface.
The real problem is, few are willing to accept anything but a positive result. Every neutral or negative indication is met with more diversionary questions meant to discredit the objective data.
Dave
Carlp said:
Hi,
Objectively we are not asking for a demonstration.
But we (I) do not accept the apriori assumption that for treatment
of ports and baffles that it is a case of finding something that exists.
(And for the EnABL process of cones anything other than known
acoustics / physics at work, and consequently it does nothing
"special", other approaches to modifying cones are just as valid.)
Yes you can run a battery of standard tests (which I assume DGO
will do) looking for differences, I assume he will run them to the
limitations of the resolution of his equipment and see if he can
find anything.
Testing ideas ? I'm not too sure about that. Even if you find
something there no reason to presume it is due to that idea.
How could we help ? We could argue about what level of deviation
in a frequency response is "significant", but its a lot easier to deal
with that if /when it comes up. What is the point if johh_k is correct
(anyone familiar with his work, but not understanding it, would be
sensible not to doubt him) and an effect will not be measurable ?
It will get very interesting if DGO does find something.
Trouble is, if he does I've no idea what that might be.
/sreten.
I want to make a comment about enable and baffle diffraction. First, baffle diffraction is a result of the need for the acoustic wave to turn and expand into a larger space. With an enable patch the direction of propagation before and after the patch remains the same, parallel to the baffle surface. Even if the enable patch is close to the baffle edge. As I said before, acoustic waves don't know the edge is there until they get there. Thus, what happens when the acoustic wave encounters the patch is that the energy of the wave which encounters the patch is scattered at the surface. It is not diffracted.
Now consider a speaker with a baffle 10" high and 5" wide. A pretty small baffle. The circumference of that baffle is 30". Now consider a circular baffle with about the same perimeter. It would have a diameter of about 10" with circumference of 10 Pi. (31.14159..."). Now assume there is an enable patch near the edge at some radius R slightly less that 5" and that the height of the enable patch is h. And assume that rather than a patch we have a continuous ring all the way around the baffle. Place a source located in the center of that baffle which radiates uniformly into 2Pi space. This will be a hemispherical wave front. When the wave reaches the enable ring the radius of the wave front will be R. The surface area will be hemisphere will be 4 Pi R^2. Now calculate the "area of the impact" of the acoustic wave with the enable ring. It comes out 2Pi R h.
Now look at the ratio of those areas: 2Pi R h /(4Pi R^2) = h/2R = h/D where D is the diameter of the enable ring. Finally the ratio of the total acoustic power impacting the ring to the total power radiated is 20Log(h/D). Thus for a painted on ring 0.005" high, 10" in diameter, the result is -66dB. So 20 Log(h/D) represents the worst case where all the energy impacting the ring is scattered. No more that this fraction of the total radiated energy can be scattered (in fact it will be much less). In addition, when you consider that at higher frequencies drivers become directional and the intensity of the wave along the baffle which encounters the enable ring will be much less than that on axis.
This should give some insight to those who care to see it .
Now consider a speaker with a baffle 10" high and 5" wide. A pretty small baffle. The circumference of that baffle is 30". Now consider a circular baffle with about the same perimeter. It would have a diameter of about 10" with circumference of 10 Pi. (31.14159..."). Now assume there is an enable patch near the edge at some radius R slightly less that 5" and that the height of the enable patch is h. And assume that rather than a patch we have a continuous ring all the way around the baffle. Place a source located in the center of that baffle which radiates uniformly into 2Pi space. This will be a hemispherical wave front. When the wave reaches the enable ring the radius of the wave front will be R. The surface area will be hemisphere will be 4 Pi R^2. Now calculate the "area of the impact" of the acoustic wave with the enable ring. It comes out 2Pi R h.
Now look at the ratio of those areas: 2Pi R h /(4Pi R^2) = h/2R = h/D where D is the diameter of the enable ring. Finally the ratio of the total acoustic power impacting the ring to the total power radiated is 20Log(h/D). Thus for a painted on ring 0.005" high, 10" in diameter, the result is -66dB. So 20 Log(h/D) represents the worst case where all the energy impacting the ring is scattered. No more that this fraction of the total radiated energy can be scattered (in fact it will be much less). In addition, when you consider that at higher frequencies drivers become directional and the intensity of the wave along the baffle which encounters the enable ring will be much less than that on axis.
This should give some insight to those who care to see it .
Graham Maynard said:
Yes, the impact of which will be even less than than that of a pure ring due to additional randomization in time of whatever scattering effect it has. This is no different than for the comparison of diffraction effects between a round and a rectangular baffle. The rectangular baffle distributes the diffraction effects in time, making it more random, thus reducing the audible impact.
Dave
/sreten.
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