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Single Asymmetric Base Shape Diffusors?? Channel Strip Plugins
Old 19th December 2010
  #1
Here for the gear
 

Single Asymmetric Base Shape Diffusors??

Contributor SAC posted the following doc - www.rpginc.com/news/library/tyndall_paper.pdf - in another thread that, additionally, contained information about single asymmetric base shape diffusors (Fig #6). Poking around the RPG website uncovers a handful of both performance venue and studio oriented products which I've never seen or noticed before that apparently utilize some of the design techniques as referred to in the first link. Although the following link points to a design that is "Bicubic", it appears to be a good, general example - www.rpginc.com/products/harmonixk/index.htm

So here is my question - are there any folk out there that have either installed, built, installed, measured, evaluated any of these types of diffusers!?!?! If so, how might one classify the general comparative performance of these designs when considering more traditional (and apparently more common) types of solutions???

Many thanks in advance for any thoughts/comments.

JV
Old 19th December 2010
  #2
Gear Addict
 

Your link to the RPG web site is broken.

The graph on this page:

RPG Diffusor Systems

Shows diffusion and scattering at HIGH frequencies only.

Perhaps prettier than QRDs and PRDs but not apparently more effective in that incarnation shown by RPG.
Old 19th December 2010
  #3
SAC
Registered User
 

They are typically employed only in large acoustical spaces where the audience/listener is in the far field. Their curves tend to render them a 'softer' aesthetic presence while simultaneously offering aesthetic variability when compared to some of the more angular alternatives. their softer angles also render them much easier to construct of lightweight molded materials.

Due to the size of wavelengths, they must be deep in order to have an effective mid/ lo-mid extension.

Modeling them is far beyond what most are capable of doing.

Their primary advantage is in large venues where traditional 2D QRD/PRD are overly complex (from a build perspective), heavy, and appear overly 'modern' (angular).

For small acoustical spaces, featuring a shallow depth, their primary function acts as a reflector and scatterer.
Attached Files
File Type: pdf Waveform_4 Page Brochure.pdf (2.91 MB, 110 views) File Type: pdf Waveform Bicubic G_Acoustical Data.pdf (104.3 KB, 163 views)
Old 20th December 2010
  #4
Gear Addict
 

I am certainly interested in the shape. In terms of modelling them for calculation, the AFMG Reflex software would be able to do it in 1-dimension - the shape can be approximated by a series of straight lines. In terms of actually building them in 2D - well they not exactly DIY.
Old 20th December 2010
  #5
SAC
Registered User
 

Quote:
Originally Posted by Sebg View Post
I am certainly interested in the shape. In terms of modelling them for calculation, the AFMG Reflex software would be able to do it in 1-dimension - the shape can be approximated by a series of straight lines. In terms of actually building them in 2D - well they not exactly DIY.

If you mean a near infinite series of straight line effectively digitizing the analog curve....maybe. That is not the function of Reflex. Read the D'Antonnio technical paper.
Personally I find little of interest in repressively reducing differential equations into an infinitely large set of Riemann sums! You couldn't even get math or physics graduate students to do that - and they are forced to do almost anything!

Additionally, they are little use in the near field in small rooms, and their effective frequency effectiveness is limited still further due to the practical sizing of the modulations which are still less efficient than more angular and diffractive surfaces such as are employed in QRDs/PRDs. there is good reason that you do not routinely see them employed on side walls of small acoustic spaces where QRDs/PRDs are routinely employed, and why the only 'general' application in such spaces tends to be limited to ceilings.

There are reasons why quadratic, primitive root, binomial, MLS, Gaussian and Galois methodologies dominate truly diffusive applications in the small acoustical space extending from theoretical ease of use to their translation into more easily constructed and effective models.

I just hope you are prepared with deep pockets, lots of time and a wealth of patience when you explore construction materials like 'bendable wood' with price tags of near $200 for pieces only ~4" x 6" x 4foot; or with infinite patience to rip grooves from now until dooms day in paneling (and nor becoming frustrated when said panels crease or break after literally spending many hours prepping just one panel - and they do as you lose/defeat the structural integrity the multi-directional laminate layers provide as you cut through up to 2 of the 3 layers leaving only one rather individually brittle layer! And you will find such material cheaper than various composites and plastics.

Please don't misunderstand my meaning. Please explore the technology! But please also be aware that my playing the curmudgeon is simply an attempt to balance your anticipation with an awareness of few of the real world issues and limitations related to the fabrication of anything but very simple models due to the dynamics of available materials. And by the time you locate materials with a sufficient ratio of rigidity to pliability I hope you can do so at a reasonable cost. Just know that many have preceded you in having explored such avenues. And be aware of, and intelligently anticipate, the challenges involved in advance rather than after the expenditure of a lot of time and money. I wish you the best in avoiding the issues, and hopefully forearmed with such an awareness you can avoid them.

But by all means, have fun.
Old 21st December 2010
  #6
Lives for gear
 
gullfo's Avatar
 

+1 for simpler math and construction from SAC.

you could create a jig as a point map using 1x1 on a plywood panel then use mesh wire and plaster to mold the units. if you have the patience create layered wood and carve and sand, assuming you drill lots of holes to create a mold for a vacuum mold and use that approach to create multiple copies. approach one is probably labor intensive (like building a model railroad set up) for many units, but for a few, probably not too bad. approach two could yield numerous quantity perhaps even for sale (assuming no licensing violations).
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