ESR Roundffusor

Can anyone vouch for these products?

A link would help us in discusing the product. Andre

http://www.zainea.com/roundffusor1.htm Sorry though I can't vouch for them. I don't see any lab data. Glenn

vicksburg - what are you trying to achieve with diffusion devices? Glenn/Andre - Ben Loftis from Studio Outfitters can assist in obtaining the lab data on these. I obtained a copy (via NDA) and would say that in certains cases these devices could be useful, but like many things, depends on the context...

I'm looking mainly for diffusion in my live room. GIK diffusors are at the top of my list... I am just curious about the roundffusors, as they are what I am looking for aesthetically. Of course, I will never make the call of aesthetics over acoustical value.

looking at the GIK diffuser and the Roundfuser scattering coefficients, I'd say they actually seem complementary with the Roundfuser having some low end absorption and mid-high range scattering and the GIK diffuser looks like a nice smooth mid and high range scattering (based on the product page info). Glenn (GIK) - can i get a copy of your diffusors' test results?

gullfo wrote:

looking at the GIK diffuser and the Roundfuser scattering coefficients, I'd say they actually seem complementary with the Roundfuser having some low end absorption and mid-high range scattering and the GIK diffuser looks like a nice smooth mid and high range scattering (based on the product page info). Glenn (GIK) - can i get a copy of your diffusors' test results?

Shouldn't it be better on the site? This is a commercial product as any other (meant for anyone).

gullfo wrote:

looking at the GIK diffuser and the Roundfuser scattering coefficients, I'd say they actually seem complementary with the Roundfuser having some low end absorption and mid-high range scattering and the GIK diffuser looks like a nice smooth mid and high range scattering (based on the product page info). Glenn (GIK) - can i get a copy of your diffusors' test results?

Glenn, Nice name BTW :lol: The test results are on the website, but if you would like send me a email at [removed], I will forward that to Jason Jones our diffusor guy to get you any info you might need beyond that. Jason is a great guy and is willing to give you any info you might need. Glenn

Eric_Desart wrote:

Shouldn't it be better on the site? This is a commercial product as any other (meant for anyone).

I would agree... certified lab test results would be best. GIK has lab tests for their traps and i was looking for the diffuser tests... ERS paid for the roundfuser tests at thier own expense (not the manf, just a reseller) so I understand if they're a bit reluctant to post them (where competitors could use it).

gullfo wrote:

I would agree... certified lab test results would be best. GIK has lab tests for their traps and i was looking for the diffuser tests... ERS paid for the roundfuser tests at thier own expense (not the manf, just a reseller) so I understand if they're a bit reluctant to post them (where competitors could use it).

The results on the GIK website are lab testing for the diffusor. Like I said though if you would like further info then please contact me. Glenn

thanks Glenn!

The roundffusor seems too shady... Guess I am gonna go with the gik d1

sounds like a plan ;)

one last bump before I make the commitment to buy the D1's... Did anyone get a chance to look at the ESR data?

i did look at the ESR data. I think that the GIK and Roundfuser products have somewhat different performance ranges (GIK tends to work nicely above 800-1000hz and the roundfuser seems to start lower and tail off lower) so I think this somewhat boils down to aesthetics as well as performance.

There is a rather in depth analysis of what can learned from the website and its links, including the patent, here at Studiotps, starting on page three of thread. It is rather technical, but it is the best I know of about the product. Andre

gullfo wrote:

i did look at the ESR data. I think that the GIK and Roundfuser products have somewhat different performance ranges (GIK tends to work nicely above 800-1000hz and the roundfuser seems to start lower and tail off lower) so I think this somewhat boils down to aesthetics as well as performance.

The low frequency performance of diffusers is kind of complicated and is often understated or overstated. The two things that matter for low frequency diffusion are size and placement - almost exclusively. Here is a link to a study done at the university of parma on scattering of diffusers. http://pcfarina.eng.unipr.it/Public/Papers/157-ICA2001.PDF Look at the picture in figure 2 of page 2. With this set-up (one diffuser with lots of space off of the floor) they get a scattering coefficient of around .4-.5 at 250 hz. Now according to the D'Antonio and Cox book, when a proper ISO scattering test is done on the skyline it has a scattering coefficient of about 0.02 (that's not an extra zero) at 250 hz. That is because low frequency performance in normal size (i.e. they will fit through your front door) diffusers is all about edge effects. The ISO scattering test completely takes these edge effects out of the question and "only" looks at the performance of the "face" of the product. If you have the diffusers set-up with some space between them you will get extra edge effects and some low frequency diffusion. But to these large sound waves all diffusers look pretty much like simple boxes of whatever their max depth is (more or less). So the difference between an RPG or GIK or Auralex or this Roundfussor at low frequencies is related only to their depth. No magic from anyone here. Now if you cover an entire wall with diffusers, with minimal exposed edges , then you will actually get a response that is like the ISO test. Here again you need depth to go low. Now there is some very slight advantages to be had with modifying some of the number theory sequences.....but, they don't seem to work as well in practice as in theory (darn reality!!!). :) Low frequency waves that are measured in meters or yards just don't notice the (comparatively) tiny stuff going on on the front of a diffuser. Jason Disclosure: I am associated with GIK Acoustics

thanks Jason, I actually have read that report before. I definitely agree that space and size are necessary whenever you expect to deal with long wavelengths. and typically small diffusers would not be effective. in the case of the roundfuser data (reported by a commercial certified lab using ISO Procedure 17497-1, Acoustics-Sound-scattering Properties of Surfaces, Part 1, “Measurement of Random-incidence Scattering Coefficient in a Reverberation Room”.) there is both diffusion and some low frequency absorption going on. that said, there are many ways to treat a room for acheiving both of those ends...

gullfo wrote:

in the case of the roundfuser data (reported by a commercial certified lab using ISO Procedure 17497-1, Acoustics-Sound-scattering Properties of Surfaces, Part 1, “Measurement of Random-incidence Scattering Coefficient in a Reverberation Room”.) there is both diffusion and some low frequency absorption going on.

The ISO Scattering test does not test for absorption. Is this up on their web-site? If, not could you point me to it? Jason

you have to contact Ben Loftis at studiooutffiters.com for the test results. they did run a series of tests including ISO-354/ASTM-C-423 for the absorption as well as the scattering test.

Hello guys. I´m having some problemas with low frequencies and searching for "low freq diffusers" I found your site and this topic. I´m not on the studio business, but I recently opened a hifi audio store and our main stereo listening room has some problems with low frequencies (wich doesn´t). We have a 35 dB peak around 70Hz and it´s harmonics, so we needed some pretty serious helmholtz absorbers to be able to make the room "listenable" ;) I´ve been fortunate enough that the bass have not lost too much speed, but now I´m feeling that we lost a bit too much os bass energy, so I´m thinking of trying to replace some of the helmholtz for membrane absorbers and maybe try some diffusion ?!? Well, anyway I´ve found some papers regarding active diffusers that should perform ok for low frequencies, notedly around 250 Hz. Does any of you guys would have some ideas to help us achieve a good balance between absortion and speed/punch ? This room has 5x6x2,8m and here´s a pic of it I thank you in advance for any tips. Regards Mauricio

Jason Jones wrote:

The ISO Scattering test does not test for absorption.

Testing for absorption is included in the ISO standard (ISO 17497) and is a crucial step. The method is not the same as an ASTM/ISO reverb room test (or impedence tube test), but it's included in the scattering standard nonetheless. (If memory serves, I don't think the resultant scattering can be calculated without first measuring the absorption of the sample.) FYI.

dmaumau wrote:

We have a 35 dB peak around 70Hz and it´s harmonics, so we needed some pretty serious helmholtz absorbers to be able to make the room "listenable" ;)

which is probably the 2nd mode on the room width... maybe some EQ to cut 70hz a bit? maybe some porous absorption using 100mm 96kg/cu m about 100mm off the side walls. or a membrane trap tuned to around 70hz? place about 1/2 the distance between the center and front/back of the side walls. it looks like a pretty live room. very nice. From Measurements

								
	ratio	size	m	sqrt(2)	bolt	ebu	iec	>5%
h	1.00	9.19	2.80	0.52	TRUE	TRUE	TRUE	TRUE
w	1.79	16.40	5.00	0.26				
l	2.14	19.68	6.00	0.15				
								
	ax 1st	~note	ax 2nd	~note	ax 3rd	~note	ax 4th	~note
h	61.29	A#1/Bb1	122.57	A#2/Bb2	183.86	F3	245.15	A#3/Bb3
w	34.32	C1	68.64	C2	102.96	G2	137.28	C3
l	28.60	A0	57.20	A1	85.80	E2	114.40	A2
								
	vol	surf	edge	area	rt60	r(ms)	Dc	mfp
ft	2966	1309	181	323	1.46	467.05	6.36	9.07
m	84.00	121.60	55.20	30.00				
								
	T(ms)	eyring	millington	Fcut	~note	Fc	~note
	8.05	1.27	1.13		28.60	A0	186.31	F#3/Gb3
								
	ratios	diatonic	stdev	modes	df	Fs	~note
h-w	1.79	vii		0.12	314	0.43	263.63	C4
w-d	1.20	iii		0.30