Sorry to say that mass alone does not damp anything. Pure physics can explain that mass only changes resonance frequency. If you have the same damping design, adding mass most likely make damping less effective.pedroskova said:
soongsc said:
Unless the resonances are shifted into frequencies at which the damping that may exist is more effective, as may be the case for the surround terminations, since they are complex impedances.
Dave
Additionally, in John K's case, the added mass itself has damping effect, which I expect to be the main reason for improvement.dlr said:
The fact that Bud had mentioned EnABL + Manboni (did I get that right?) would provide better results is also supportive of the positive effects of damping and mass loading. These are all tools to accomplish better results, and should be used with understanding.
dlr,
I did post with Dr Geddes for a bit. He was interested but was not willing to test anything himself. Really, just reporting obvious effects here.
maxro,
A fellow in NJ actually did a double blind test (not intended as a pun in any of the ways it could be taken as one). In one of the two groups, there were two blind folks. Their comments supported that the coherent information coming from a pair of EnABL'd speakers was painting a clear three dimensional picture of what they were listening to. They both apparently said they could have walked around on the stage the musicians were playing on.
There is a faint possibility this man still lives and if so, I can probably find him for comments. But this was quite a while ago.
Bud
I did post with Dr Geddes for a bit. He was interested but was not willing to test anything himself. Really, just reporting obvious effects here.
maxro,
A fellow in NJ actually did a double blind test (not intended as a pun in any of the ways it could be taken as one). In one of the two groups, there were two blind folks. Their comments supported that the coherent information coming from a pair of EnABL'd speakers was painting a clear three dimensional picture of what they were listening to. They both apparently said they could have walked around on the stage the musicians were playing on.
There is a faint possibility this man still lives and if so, I can probably find him for comments. But this was quite a while ago.
Bud
pedroskova said:
Do you mean you don't believe EnABL makes a difference, or don't believe the explanation?
Personally, I have more of a sense of adventure - and was eager to try it on my own drivers. I have tried many many hifi tweaks. Most made no audible difference whatsoever - this one did. I also identify with soongst's difficulty in describing it. The driver simply throws out the sound differently.
Having tried it - I feel qualified to participate in this thread. My gut feeling goes down the "added damping without significant mass" ideas. But watching with interest.
All getting a bit repetitive sometimes tho ...
pedroskova said:
Just to clarify, I did not say mass damping, or if I some how did that is not what I meant. I believe I said, or should have say, added mass and damping effects, two separate issues. Why do I say that my results show that? 1) Because we can see shifts in the frequency of some of the resonances. In a mechanical system this can occur only if there is a change in mass or compliance. I'm it would be hard to quantify any change in compliance, although there may be some as well, but it is clear that the moving mass has changed. So, we know we added mass and we know that adding mass result in a frequency shift. The result is consistent with accepted physical behavior of cone vibration/breakup. 2) A similar argument applies to damping. The magnitude or Q of the some of the resonances are reduced of resonances are eliminated all together. This can only change due to dissipation.
So there is a degree of consistency here between what has been done, what the accepted physics of vibration tells us should be the result, and what the actual observed result is. You know what they say, if it looks like a duck, walks like a duck, quacks like a duck; then the odds are pretty good that it's a duck.
With regard to modifying a driver, I agree. It has been shown in evey case presented he that appling the process alters the frequency response and not necessarily in a favorable manner.
BudP said:
Well Bud, I've tried to be polite and as long as the discussion was related to drivers I could do so. But I'm affraid when you start talking about edge diffraction the discussion goes from one of snake oil to pure BS.
john k... said:
I'm curious. Why do you think that?
Please understand that I know little about audio, but I'm learning every day 🙂
Bachelor of Science?😀john k... said:
I think the best way to find out is for Bud to just send you two wave guided drivers he has heard a difference in, probably to a few people as well to measure and find out?
Certainly it is more appropriate for someone that has more experience in driver improvement to call something snake oil. Even with my measurements I could not say whether this will have effect on diffraction performance. Hmm, I just remembered something while I was testing a driver. Maybe I could give this a quick run the next time. Since this will be a TB W3-1285SB driver, I will make the results available.
john k... said:
OK ... This didn't make make me any wiser, not that you are to blaim for that 😉
Do you have a reference as to where I might get enlightened on the subject on wich you disagree?
Thanks in advance.
-Klaus
john k... said:
Instead of just discarding it as with no merit with no consideration, perhaps as a thot experiment looking at it from the POV that it does and then considering how the H it could might be useful in getting your head around the problem of determining a mechanism. I don't think mass/damping has any hope of explaining it. The audible changes on a driver are a whole magnitude greater than i had been able to achieve with remarkably similar techniques (when viewed purely from mass/damping POV) and furthermore, in a different direction.
dave
I agree that a statement like that can cause confusion if it is not understood. But if we do not know the thickness of the paint, a normal dot of oil based paint dries much thicker than one might expect. Plus the fact that stiffness of the paint is no longer an issue. Theoretically it does disrupt the laminar boundary layer depending on thickeness of the pattern and speed of flow.john k... said:
I agree that it will probably not effect the lower frequencies, and you will still see effects of baffle diffraction. But there would be change in the diffraction effects on the measured frequency response.
Correct me if I'm wrong. Since SPL measures the pressure as relative to standard air pressure, regardless of frequency; thus at higher frequencies of the same SPL, pressure change from one peak to a node and to the negative peak takes place in shorter time, and so the flow must be faster to accomodate this pressure change. How to use this understanding? I will leave it up to you all to consider.
soongsc said:
I don't know why you and others insist on trying to make something out of this. It is without question impossible to have any measurable or audible effect. I have, as I said before, spent literally years measuring and testing various materials, shapes, sizes, densities, placements, etc., on baffles to ameliorate diffraction. Tiny paint lines or anything that tiny on the edge are pointless, period. Even 1/4" thick 100% wool felt is only moderately effective, it generally takes 1/2" or so to have a significant impact. Higher frequencies exhibit almost no diffraction in any case.
It will not work, end of story.
Dave
John K,
Soongsc does bring up a good point. I cannot say with certainty that there is no diffraction at low frequencies. I have been in this argument about diffraction before, without there being a clear description of the audible effects of diffraction or of how to measure it.
My understanding is this. That the audible effects of diffraction are a localization of sound source to the edge that is diffracting the signal.
That a portion of the energy that is not emitted off of the baffle, into adjacent air is reflected back across the baffle, in standing wave mode.
That another percentage of the energy actually wraps around the edge and continues to emit into the air as it moves across this second surface.
In addition to this localization, which appears to be primarily a mid frequency function, there is also a lobbed presentation of the sound out in the sound, field from the baffle edges. This lobe effect covers about a 30 to 45 degree angle with median parallel to the baffle plane.
This is my understanding of the audible effects of diffraction from a hard, non rounded, 90 degree edge, on a speaker mounting baffle.
Also, all of the ones I have encountered to date, have been commercial boxes, so the baffle has not been large, as is sometimes found in open baffle systems, which I have no experience with and so am not including in my statements. Also all of these treated baffles have been from multiple driver systems and all of the drivers involved have been fully EnABL'd, before the baffles were treated.
By now you should know I am describing a real phenomena. I just may not have the correct definition and we may be misunderstanding each other.
Now, please describe for me what diffraction effects are, how they are perceived and how to test for them. Then I can describe what I hear, with edge treated baffles.
Then we can wrangle about how much BS I am spreading around.
Bud
Soongsc does bring up a good point. I cannot say with certainty that there is no diffraction at low frequencies. I have been in this argument about diffraction before, without there being a clear description of the audible effects of diffraction or of how to measure it.
My understanding is this. That the audible effects of diffraction are a localization of sound source to the edge that is diffracting the signal.
That a portion of the energy that is not emitted off of the baffle, into adjacent air is reflected back across the baffle, in standing wave mode.
That another percentage of the energy actually wraps around the edge and continues to emit into the air as it moves across this second surface.
In addition to this localization, which appears to be primarily a mid frequency function, there is also a lobbed presentation of the sound out in the sound, field from the baffle edges. This lobe effect covers about a 30 to 45 degree angle with median parallel to the baffle plane.
This is my understanding of the audible effects of diffraction from a hard, non rounded, 90 degree edge, on a speaker mounting baffle.
Also, all of the ones I have encountered to date, have been commercial boxes, so the baffle has not been large, as is sometimes found in open baffle systems, which I have no experience with and so am not including in my statements. Also all of these treated baffles have been from multiple driver systems and all of the drivers involved have been fully EnABL'd, before the baffles were treated.
By now you should know I am describing a real phenomena. I just may not have the correct definition and we may be misunderstanding each other.
Now, please describe for me what diffraction effects are, how they are perceived and how to test for them. Then I can describe what I hear, with edge treated baffles.
Then we can wrangle about how much BS I am spreading around.
Bud
Well, we don't know what your driver/speaker was, how the setup was, results, etc. But I do know if your drivers/speaker have a CSD that drops some 12db below in like I have shown, you will hear differences. I have hear baffle diffraction differences ever since I started using the Jordan Watts driver, there is no doubt to me that diffraction does effect the sound reproduction. But the effects can be masked by other aspects, If you can show a system that meets the CSD performance I posted, and impedance variation within +/-2 Ohm from 100Hz ~20KHz, then you might hear significant differences. If your system cannot make absolute polarity differences clearly audible, then you are really far from what we are taling about. I'm sorry if it upsets you. But this is just sharing my experience. Until then, we are not comparing aples to apples.dlr said:
BudP said:
I can provide some links to some of the answers.
The first one is good start for the basics. Your post makes me believe that it would be a good start.
Baffle Diffraction by Andy Unruh
The next one shows what to expect to some degree. It was an early page, but has pictures and specific measurements that document the effect. Measuring it requires nothing more than standard MLS measurement systems as one means.
Diffraction Effects and Amelioration with Felt
If that isn't enough, get a copy of the June 2005 audioXpress. You'll find a fairly lengthy article in it that documents with pictures and measurements all of the steps taken for diffraction control for one specific baffle example.
I'd also suggest getting the Baffle Diffraction Simulator at the FRD Consortium and the documentation that goes with it. Just google it.
Dave
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