Flat Fusor

[soundslikejoe]

RPG Diffusor Systems

I'd like to hear what the informed people think about this product. I'm considering using these along my back wall as a sub for two absorbing panels.

[soundslikejoe]

come on... 40 views no reply.

Anyone have any comments on using diffusion in small rooms (12x14x8)?

[bpape]

What are you using the room for?

The binary type diffusers can work pretty well - just don't expect them to go terribly deep. If the room is for mixing/control, then the rear wall generally (in a smaller space) will be better off with some broadband bass control to deal with nulls off the rear wall.

Bryan

[soundslikejoe]

The room is for mixing but will have some tracking. Currently it has a wealthy reverb decay and no treatment. The floors are hardwood and I have two extra angled walls (barn shape).

I plan on trapping the vertical corners, covering 1st reflection points, and using a 6" trap over the mix position.

I was thinking flatffusors either on the ceiling (rear of room) or on the angled side walls (rear).

[Ethan Winer]

Originally Posted by joenovice

come on... 40 views no reply.

Half the people helping in this forum work for companies selling acoustic products.

I can't speak for anyone else but RealTraps, but as a matter of policy I generally do not comment on the effectiveness of products from other companies.* Maybe someone else who knows the RPG line can chime in?

* Except for blatantly fraudulent products.

Anyone have any comments on using diffusion in small rooms (12x14x8)?

As for diffusion generally, I'm a fan, even in smaller rooms. More here:

All About Diffusion
Hearing is Believing

--Ethan

[foxfyr]

The various binary diffusors offered by RPG are based upon quite solid physics (and math).

In order for a surface to diffuse reflected sound waves, it can do this via a shaped surface or by varying the impedance of the incident surface.

In this case the variation in impedance is accomplished via the patterning of reflective and absorptive surfaces. And as such they are considered hybrids, as they exhibit characteristics of both absorbers and reflectors to accomplish a result between that of a pure absorber and a purely reflective diffusor.

This concept is not new. In fact, this technique is commonly applied in the form of spaced absorptive panels on a reflective (wall) surface.

The biggest change here is that binary mathematics have been employed to generate patterns offering controlled diffusive and absorptive characteristics. The trick, as with MLS (maximum length sequence analysis) techniques is to generate a binary sequence that results in an optimally flat power response. This means that the pressure amplitude scattered is constant with respect to the transform variable.

I am reasonably sure that few care but, if we had an equation editor I could post the equation for the pressure amplitude for a variable planar surface. The generated binary number sequences (see Schroeder's works for much more mathematical detail) result in various scattering topologies dependent upon the selected sequence. (PM me if you care - but I won't be hurt if none do! ;-) )

All of that amorphous stuff results in a flat panel 1 or 2 dimensional hybrid absorber/diffusor.

I have not had first hand experience with the Flatfusor, but I have witnessed the effectiveness of the selective frequency BAD LF absorber/Mid-high frequency diffusors and they are quite effective- if also quite expensive per unit surface area. But that aspect is for you to determine. (Edit! I stand corrected, as I was mistakenly under the impression that they had introduced a slightly different model with a different name - when they are indeed the SAME product with a different name! Duh! ;-)) )

As far as their effectiveness, the measured specs are reliable.

And on the tangent of measured diffusion specs...

All should be aware that Ron Sauros is about to drop a bomb on the techniques regarding the measurement of diffusion, in particular. And area where there has been MUCH uncertainty in models, as well as practical techniques! So much so that when Leo Beranek heard the recent abbreviated synopsis of his preliminary findings and tests, that Mr. Beranek 'cornered' him and insisted this be published and presented at several other functions! Quite an compliment indeed! Much fun is anticipated!



...Now to post this and to go back and edit it for fat figured spelling mistakes - strange how the editor only works after it has been posted....hmmm...

And no, I represent NO commercial interest.

[Glenn Kuras]

Originally Posted by Ethan Winer

Half the people helping in this forum work for companies selling acoustic products.

I can't speak for anyone else but RealTraps, but as a matter of policy I generally do not comment on the effectiveness of products from other companies.* Maybe someone else who knows the RPG line can chime in?

* Except for blatantly fraudulent products.




--Ethan

Just to add to that, companies need to be a bit careful to comment about others products as there are STRICT rules here on GS about bashing competitors. Not that there is any problems with the RPG product, but any comment we do say could be read as a negative. Kind of a tricky place to be in at times.
But (I can only speak for GIK) we are more then happy to give you any info on placement of a competitors product, as Bryan did above.

[andrebrito]

I have used and sold these where I live, they work in terms of absorption and diffusion. I have never used these as bass trap, altough with the air cavity involved you can extend the range to lower frequencies. I only use them on tracking rooms to control reverberation and yet give that extra spark from high frequency diffusion.

They are not that expensive either, way less than other RPG diffusers.

Another good thing is that they can be sold in huge panels so they can be applied to larger spaces.

[foxfyr]

"The BAD™ panel offers reflection control above 1000 Hz, by diffusing the sound, rather than absorbing it. Below 1000 Hz, the BAD™ panel offers pure absorption, with improved efficiency compared to a standard fabric wrapped panel" RPG Diffusor Systems


And in an attempt to clarify that which definitely had me going for a bit, the BAD and the Flatfusor are the exact same product!

Apparently the differing BAD and Flatfuser nomenclature is/was an attempt to 'brand' the "BAD" product for identification in the pro market space.

But they are functionally identical - a hybrid frequency selective LF absorber that remains reflective/diffusive in the mid and high end in order to augment the finite semi-diffuse sound field in a small acoustic space. A useful product indeed.

Have fun.

[jayfrigo]

See also, recent, if short thread on the subject here:
DIY Binary Amplitude Diffuser anyone?

[soundslikejoe]

Great posts. I'm especially enjoying Ethan's video on diffusion!

Question from video -

You state that diffusors should be a minimum of 3" deep. Does this apply to a binary design (1" deep) or other versions?

[andrebrito]

No, it does not.

[Ethan Winer]

Originally Posted by andrebrito

No, it does not.

Well...

[jayfrigo]

Originally Posted by joenovice

Great posts. I'm especially enjoying Ethan's video on diffusion!

Question from video -

You state that diffusors should be a minimum of 3" deep. Does this apply to a binary design (1" deep) or other versions?

Binary doesn't need the depth in the same way that QRDs do. BADs also don't provide the temporal component of diffusion that QRDs do. However, BADs can be made to absorb lower frequencies by increasing the depth of the absorber behind the amplitude grating.

These things have advantages and disadvantages. They don't replace QRDs, either 1D or 2D, but they do offer additional tools to be used in conjunction with other treatments. BADs for example can be good to use on the upper parts of the side walls in theaters. I wouldn't say that they are interchangeable with a QRD for the traditional approach to treating the back wall of a control room.