as a believer in Austrian Laissez Faire Capitalism as well as Darwin's theory of Evolution i believe that competition is essential for progress.
in an online debate ( in which i have little to gain personally ) i would not consider myself a winner if the truth ended up loser.
the truth loses when arguments which are not logical in nature succeed. while i would be lying if i said i never use arguments that appeal to emotion rather than reason i typically reserve such arguments for people and/or discussions that are hopeless to begin with ( which is not the case here ).
i would be more than happy to "lose" in the argument that foam can attenuate any frequency down to DC if that is in fact the case. i have no product to sell that hinges on one interpretation of reality or another.
the winner in the argument is not the person who leaves with his original opinion but one who leaves with the correct one.
also i would not presume that any of us here necessarily have the resources to come out with a definitive answer to the question. perhaps the best we can do is leave with more questions. this is perfectly fine too as long as we leave with better questions than the ones we came with.
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here is the Question i have for you Geddes. take a look at an aperiodic vent:
Aperiodic Speaker Enclosure Design
how can it possibly work ?
well it certainly doesn't work through isothermal/adiabatic thing because it is not in contact with the entire volume of air.
it also cannot possibly work by slowing down the speed of sound for the same exact reason - it is not dispersed through the volume of air.
and yet it does affect response at the very lowest of frequencies.
doesn't this contradict your theory that damping material only slows down the speed of sound at low frequencies without providing damping ? if the aperiodic vent isn't providing damping then what is it providing ?
Aperiodic Speaker Enclosure Design
how can it possibly work ?
well it certainly doesn't work through isothermal/adiabatic thing because it is not in contact with the entire volume of air.
it also cannot possibly work by slowing down the speed of sound for the same exact reason - it is not dispersed through the volume of air.
and yet it does affect response at the very lowest of frequencies.
doesn't this contradict your theory that damping material only slows down the speed of sound at low frequencies without providing damping ? if the aperiodic vent isn't providing damping then what is it providing ?
Yes, I have done extensive work in modeling enclosure absorption, most notably a paper in AES some two decades ago. So I have a very firm grasp of what reality is in this regard. The model matches that reality pretty well, as well as most models of this sort. The point is that it matches this reality using a completly different mechanism than has here-to-fore been assumed. Which approach is correct? I have no idea and, as I say in my book, no interest in pursuing it further (it would be an interesting student thesis however). To me its an academic question which causes the box enlargment effect, the fact is that this effect is real. Its just interesting to note that it may not be the thermal approach as you stated.
what about the possibility that al 3 effects operate in parallel ?
1 - thermal one
2 - flow resistance one
3 - yours ( complex speed of sound ??? )
?
... or the possibility that they are all just limited models trying to describe the same thing? Shocking.
Don't forget that cooperation is also important. Otherwise, social animals would not have evolved. And thus there wouldn't be a WWW. 😉
i remember that as well.
human emotions ( love, fear etc ) are simply optimal ( either for an individual or species as a whole ) survival strategies hard wired into the brain.
survival however is not the same as progress. progress still takes competition.
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In all likelyhood, they are both correct to an extent and the real situation is some combination of them. While it cannot be proven, I have always found that in Physics, if something CAN happen mathematically, it does happen. Hence, if both theories are mathematically correct then they will both happen. The interactions between them then makes for a very complex situation. More than I care to delve into.
There is no contradiction, its an entirely different thing and what I modeled doesn't apply. My analysis was for a closed box where the velocity must go to zero at the walls. The vent does not fit this criteria and in fact is the exact opposite with a very large velocity, making it very effective at damping even down to LFs. Different animals.
And yes this approach does work, we used it in automotive decades ago. But its no panacea. IF, and thats a big if since it cannot be done, one has a leak that is purely resistive with no mass effects then the apparent enclosure volume goes way up. But ANY mass effect will resonate with the box volume and then you just have a poorly tuned bass reflex. If you are going to do bass reflex then just tune it properly. In practice it takes a fairly large "vent" filled with absorber to get the resistance much much greater than the mass. This becomes impractical.
I have thought about doing this for a sub where I can't get it tuned low enough to be effective at VLF without being huge. I have built leaky rear boxes on bandpass tuned front enclosures before and they can be made to work, but again get bulky and complex.
disagree but will take a break from this discussion. it is eating up too much of my time.
I hate to jump in just to criticize, since I respect your (and Borat's) opinions, but this is not likely. I work in a field where mathematical models are a dime-a-dozen, and there is no reason whatsoever for a mathematical theory to be physically correct or useful, even if it is by some measure internally consistent. If two different theories (models) result in similar physical predictions, then they are only apparently different, not really. perhaps one theory is the limiting form of the other; for example, classical mechanics and relativistic mechanics, although apparently different, are the same theory in the limit of small v/c.
I'm not entirely certain I agree with this either, but I accept your point. This is the kind of philosophical discussion that does not lend itself to posts.
I would just point out that there have been several mathematical theories that were believed to not "be physically correct or useful", but which turned out to be both. Non-Euclidian geometry for example. There are many many others. The point being that neither of us will live long enough to find out if we were right or not.
I've been using this stuff with great results. It looks like Meniscus has some of that denim batting.
I got a bag of that same bamboo fiber but haven't tested it yet. After doing some research, I found the diameter of bamboo fibers is in the 100-300 micron range; much much higher than PET, wool or FG. So I'm not optimistic it will be as effective.
Will report back after doing some comparative Fc and response tests.
Anybody else tried bamboo?
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