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Quote:
Originally Posted by ObsceneJesster /forum/post/0


I was browsing Ebay when I came across a listing for a sound diffuser that looks like someone just cut some wood at various angles and glued them into a case with no rhyme or reason. Would this thing actually work?

http://www.ebay.com/itm/1-x-1-WOOD-a...#ht_500wt_1287

"actually work" is vague ....key is over what freq range and how effective is it as diffusing/scattering.

Ask them for their 3rd party test data to see how effective it is.


If you buy it without any specs on what it will do all you know for sure is you have firewood, possibly some random artwork if you feel that way.

How can they be held to any performance changes?


[edit 9/21 8:30am EDT]

I posted these Q's in the eBay listing
Quote:
Dear fly-by-night-owl,


Over what freq range and how effective is it as diffusing/scattering.

Do you have 3rd party test data to see how effective it is?
 

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Even bookshelves in rooms can help diffract soundwaves so enough of these will cause diffraction too.


No snake oil at all because enough of them do change the response in room. 10 of these is around $450 though (that is only a 2'x5' area) so its going to get expensive to have enough that matter. At this point considering they are ugly/not painted you might as well search online for those nice >= $500 QRD solutions.
 

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Brilliant. Take random scrap pieces. Attach to backer. Sell.
 

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Quote:
Originally Posted by penngray /forum/post/20975295


No snake oil at all because enough of them do change the response in room. 10 of these is around $450 though (that is only a 2'x5' area) so its going to get expensive to have enough that matter. At this point considering they are ugly/not painted you might as well search online for those nice >= $500 QRD solutions.

it is snake oil because it is a device that will scatter specular energy but it will not diffuse, as labeled in the product title and description. the polar responses, design frequency, HF cutoff, plate frequency, etc are unknown vs using number theory such as quadratic residue or primitive root sequences. the product appears to be random blocks of wood without any consent or consideration into the principles of good diffuser design.


adding to the list of issues, since the characteristics of such a scattering device are unknown, then one does not know how to apply multiple periods or modulation of such a device in order to minimize grating lobes. blind application of 'treatments', in my opinion.
 

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In theory no different then bookshelves. which has been recommended by experts for 30 years.


Could it work? Yes it could work. Is it following the mathematics, hell no, its definitely far from perfect (prefection is a waste of time in the real world)!! Its it ugly, absolutely ugly, waste of $$$ too if you think about it but I like the people who stimulate the economy myself and not anyone that practices theories only online



Its a funny way to define the term "snake oil" though, I guess some people do not understand the root/history behind that term.


I do wonder why people care about "blind" doing anything. There is are billion $$ industries out there for risk taking, I suspect those that concern themselves with "blind" anything are not really risk takers at all. Its $500 to take a change??? Thats cheaper then the past weekend in football bets/golf bets!!!


What if 8 of them work well?? I can not find another source that cheap....damn they are still ugly though. The rewards are always for those who take the risks.
 

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Quote:
Originally Posted by Chu Gai /forum/post/20975556


Brilliant. Take random scrap pieces. Attach to backer. Sell.

Absolutely, great way to remove all that scrap wood



If there is a response change and someone likes it who the heck is going to argue against it??? Oh, the theory police/non-risk takers....blah, no fun stuff. The dumbest guy I know is amazingly the richest guy in the room because he does not fuss/stumble too much over theory and he has taking chances that others wouldn't
 

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Quote:
Originally Posted by ObsceneJesster /forum/post/20973153


I was browsing Ebay when I came across a listing for a sound diffuser that looks like someone just cut some wood at various angles and glued them into a case with no rhyme or reason. Would this thing actually work?

http://www.ebay.com/itm/1-x-1-WOOD-a...#ht_500wt_1287

Jesster,

collo has written an absolutely glorious technical guide that is easily digestible for the novice regarding quadratic residue diffusers, designs, and their performance.
http://www.subwoofer-builder.com/qrd.htm


if you're up for a read, it will provide sufficient insight...
 

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Quote:
Originally Posted by Gizmologist /forum/post/20975234


This is what is called audiophile snake oil. As mentioned it could be used for firewood or a doorstop.

To be fair, the price is not that much higher than that of firewood. Unfortunately, it might require some disassembly, while most firewood comes ready to use out of the box. So it's not such a great deal either.
 

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A stack of firewood would serve a dual purpose, after you decided that there was not a marked audibly pleasurable alteration of the room acoustics, you can simply burn the experiment. Remember also that the effect of real wood diffusers are also calculated on the TYPE of wood as well as the shape, treatment, mass and location of said diffusers.

This little gem appears to be cheap soft one and Elmer's glue.


Woodshop 101 aka what to do with all those scraps.
 

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Quote:
Originally Posted by Gizmologist /forum/post/20978093


Remember also that the effect of real wood diffusers are also calculated on the TYPE of wood as well as the shape, treatment, mass and location of said diffusers.

type of wood?
 

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Wood come in all types of densities and although a MUCH larger amount of word used in MUCH larger panels and diffusers around a room would be necessary, softer woods like white pines have one degree of absorption and harder woods like oaks and teaks offer a different function; more of a reflection vs absorption.


Conference rooms are subject to a lot of echo so the interior designers will use decorative wood paneling or large accent pieces as well as carpeting with dense padding to help absorb and deaden the room.


One example you can see on-line is the Morton Meyerson Performing Arts hall in Dallas, Texas. The entire hall is paneled in a rare wood, all taken from the same tree family in the same forest in one part of the world (can't remember which) so the tonality and acoustics of the room would be superb.


During the construction of the hall, there was a lot of news coverage about the choice of the wood and its characteristics.


That being said, the little playschool-style wood block sculpture shown would be an interesting door stop.
 

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Quote:
Originally Posted by Gizmologist /forum/post/20979730


Wood come in all types of densities and although a MUCH larger amount of word used in MUCH larger panels and diffusers around a room would be necessary, softer woods like white pines have one degree of absorption and harder woods like oaks and teaks offer a different function; more of a reflection vs absorption.

i disagree; do you have any data regarding reflection/absorption coefficients of different types of wood in the context of a 2D schroeder diffuser?









also, point 6 in this document:
http://www.rpginc.com/news/library/tyndall_paper.pdf


(this is also why you do not wrap your diffusers in fabric)


different types of wood may be more beneficial depending on the structural integrity if the wells are extremely long (prevent sagging)...but i would not source the root of your absorption issues of a schroeder diffuser based on the type of wood used.


it reminds me of this thread (takes a little while to get going, but brilliant read):
http://www.gearslutz.com/board/studi...-question.html

Quote:
Originally Posted by SAC /forum/post/0


I am fascinated with the all too common idea of people liking the sound of (fill in the blank: cement, wood, macaroni, vinyl tile, ceramic tile, avocados (in season), stone tile, etc.) in regards to a 'solid' reflective surface.


They are all reflective.


The only 'sound' that is imparted is if they are resonant, which is an error, not a feature; or absorbent; or if they have some surface patterning sufficient to effectively diffuse or scatter energy... And still, that is not integral to the material itself.
Quote:
Originally Posted by SAC /forum/post/0


You don't even know that there are different components of reflection! We have made a fundamental distinction based upon the different components, and you just lump it all into one pot and call it the "same". Its a "reflection"!


You still haven't a clue as to the distinction between the resistance and the reactance of acoustical impedance.


And why pumice and granite which are both "rocK' behave differently. And why cypress and oak which are both wood behave differently.


But why two dissimilar materials such as oak, securely anchored to a non-resonant base and granite securely fixed to a non-resonant base will reflect similarly.


Do you have any idea what the differences in the resistive potential energy component and the reactive real component of complex impedance even mean?




furthermore:
http://www.realtraps.com/art_surfaces.htm
 

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Just a lot of real world (40 years) experience in the corporate boardroom business. You see theories and controlled environmental experiments do not always translate well to the real world.


Did you Google the Morton Meyerson story? Not as much technical info as you may desire but the acousticians who designed it are world class as is the result of their efforts. The hall is considered one of the finest in the world, and the designers attribute a GREAT deal of that to the wood choice.


I my world we learned by taking what the aesthetician-type decorators started with and learned what worked and what didn't. Seat of the pants, but quite successful. I am old school and got started in the biz before it really was a business. Pretty much the way everybody got started.


Theory is great as long as the real world experience verifies the theory.


Hence the definition of the term theory.
 

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Quote:
Originally Posted by Gizmologist /forum/post/20980884


Just a lot of real world (40 years) experience in the corporate boardroom business. You see theories and controlled environmental experiments do not always translate well to the real world.


Did you Google the Morton Meyerson story? Not as much technical info as you may desire but the acousticians who designed it are world class as is the result of their efforts. The hall is considered one of the finest in the world, and the designers attribute a GREAT deal of that to the wood choice.


I my world we learned by taking what the aesthetician-type decorators started with and learned what worked and what didn't. Seat of the pants, but quite successful. I am old school and got started in the biz before it really was a business. Pretty much the way everybody got started.


Theory is great as long as the real world experience verifies the theory.


Hence the definition of the term theory.

what does any of your previous post have anything to do with the topic at hand?


to re-quote your original statement of which i replied:

Quote:
Originally Posted by Gizmologist /forum/post/20978093


Remember also that the effect of real wood diffusers are also calculated on the TYPE of wood ....

so, you do not have any data to prove your 'theory' to support that different types of wood will have significant impact on absorption and scattering coefficients in the context of acoustic diffusers? yes or no...


could you elaborate on how one 'calculates' a diffuser based on the type of wood?

Quote:
Originally Posted by Gizmologist /forum/post/20980884


Theory is great as long as the real world experience verifies the theory.


Hence the definition of the term theory.

then i look forward to the data to support your theory and claims...
 

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Ever worked an audio system into a room with all dense and hard surfaces? When the walls are double layered 1/2" sheetrock (very common or) 5/8' commercial grade, the floor is either concrete or some sort of stone or synthetic (ceramic, etc.) and the ceiling is also sheetrock? The room will be exceptionally live.


We have obviously had carpeting installed, and if the client wants some wood accents or furniture such as wall to wall cases or just a decorative paneling, we look at the various wood types available that could be used for the walls etc and from that, depending on the time domain readings and listening to the room as originally built, decisions are made as the what types of woods are used. Hardwoods such as oak, maple, and teak are highly reflective.


Soft woods such as most any grade of finished pine or ash are much more absorbent- to a lesser degree than actually using sound deadening panels, but along the same lines. We also have used baffles of varying designs -usually equilateral pyramids- on domed ceilings for the same purpose- sometimes wood or bamboo sheeting and sometimes sheetrock.
 

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Quote:
Originally Posted by ObsceneJesster /forum/post/20973153


I was browsing Ebay when I came across a listing for a sound diffuser that looks like someone just cut some wood at various angles and glued them into a case with no rhyme or reason. Would this thing actually work?

http://www.ebay.com/itm/1-x-1-WOOD-a...#ht_500wt_1287

This will actually work if you cover all walls and ceiling with these things. It is called anechoic chamber.


But I do not think you want sit in that kind of room.
 
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