Foam or Fiberglass in my corner 'absorbers?"

[HarryO]

"This is probably a who cares, but Im pressing on with this little project"

Very nice work! Functional and pleasing to the eye. Good luck in getting your acoustics tuned up.

I'm behind times in tuning up my listening area. After listening to the room treatments at the Pilgrimage I'm actually more confused than before. I didn't understand some of the treatments done at the Klipsch facilities but If their intention was to prove the treatments can make a difference in the sound they succeeded. I've been playing with foams since sunday after the Klipsch shindig. I've made major gains keeping down reflection in my lousy listening area. Fortunately it is a small area and just minor treatment so far has made major "improvements" or better yet, "differences". From what I've found out so far with my hands on approach it like anything else in the audio world it's going to be personal preference and compromise. Just getting a late start on room treatments so my comments shouldn't get much notice. But I've found out for certain they do make major differences.

I'm looking forward to your results when your great looking project is completed. Comments and pics please upon completion.

Good post and good timing.

Harry

[anarchist]

Wow! Can we say "dead"?!

A

fascinating before and after ETC. One wonders just what they were

trying to accomplish as there are MANY significant issues still

remaining!

For the sake of brevity, I removed the remainder of mas's monologue.

The article specifies this is a great listening room based on the results of those measurements. Mas claims it is a disaster.

For us laymen, such contradictions do little to breed confidence.

They state the goal was to reduce reflections and smooth out the base response. The graphs appear to demonstrate that. Isn't the variance in the second graph evidence of the diffusion? Honest question.

Why the volume levels are different is a question mark? Normally, one would graph (or test) using the same test parameters to isolate the differences and make it easier to compare.

It would seem to me highly stupid of Auralex to use this particular example as their primary case study if it is so flawed. It seems even more unlikely a bunch of Klipsch engineers designing speakers would use such rooms if they were so bad.

I look forward to someone reconciling the differences in interpretation. Perhaps provide some references which support your position. I would much prefer to know I am reading something based on objective criteria rather than personal preference colored as fact.

[gaspr]

Some good questions Anarchist...I hope this sparks some informative

discussion. I think that all of Mas's interpretations are

"supported by objective criteria". There is a thread in the

architectural section called "room acoustics- large and small

rooms". Lots of fact based and well supported info in that

thread...a good place to start.

[Strabo]

IMO, the large and small room acoustics thread should be required reading for any audiophile. It explains the usefulness of ITD which as the graphs show there is almost no ITD in this room.

In a nutshell, this room was deadened with little or no diffusion. The proof is in the graphs before and after showing the huge reduction in sound level with no attention given to the spikes.

If I understand diffusion correctly, diffusion should smooth out the peaks and valleys of the sound pressure over time. What we see is in the graph is attenuated (quieter) peaks and valleys. They are the same magnitude, but at a lower level.

I think the point is that if I was paying someone to "fix" a room, I'd expect them to do more than build me a padded cell. I'd expect them to be experts at actually fixing the problem. What I see is that they are experts at selling absorbtion which hides the problems instead of fixing them.

[jacksonbart]

Silly putty. Actually you can just leave it in the plastic egg, but it has to be removed from the packaging to have a real affect.

[DrWho]

Wow! Can we say "dead"?!

A

fascinating before and after ETC. One wonders just what they were

trying to accomplish as there are MANY significant issues still

remaining!

For the sake of brevity, I removed the remainder of mas's monologue.

The article specifies this is a great listening room based on the results of those measurements. Mas claims it is a disaster.

For us laymen, such contradictions do little to breed confidence.

They

state the goal was to reduce reflections and smooth out the base

response. The graphs appear to demonstrate that. Isn't the variance

in the second graph evidence of the diffusion? Honest question.

Why

the volume levels are different is a question mark? Normally, one

would graph (or test) using the same test parameters to isolate the

differences and make it easier to compare.

It would seem to me

highly stupid of Auralex to use this particular example as their

primary case study if it is so flawed. It seems even more unlikely a

bunch of Klipsch engineers designing speakers would use such rooms if

they were so bad.

I look forward to someone reconciling the

differences in interpretation. Perhaps provide some references which

support your position. I would much prefer to know I am reading

something based on objective criteria rather than personal preference

colored as fact.

I just wanted to point out that Mas was able to determine what the

treatment was like in that room without having ever been there! I think

that speaks volumes to his ability to interpret the data.

Would you happen to know which room at Klipsch was being used for this

case study? I have a feeling that it was the AB testing room, but I'm

not sure. I am certainly nowhere near experienced enough to figure out

which room we heard based on the measurements alone (maybe if I had

measurements of all of them where we can compare against what we heard).

I'm not sure why Klipsch seems satisfied with the Auralex thing, but I

believe it's a more recent addition to their rooms - and they mentioned

on many occasions that they were still tweaking. They've always treated

the rooms to some extent, but I was under the impression that the

Klipsch engineers were doing it by ear. All I know is the rooms didn't

sound this bad 2 years ago (except for the combo reference heritage

every speaker in the world room). For what it's worth, they didn't sound amazing great 2 years ago either.

During the town meeting the Auralex dude briefly explained their

approach to acoustical treatment. I was hoping to get an idea of where

they are

coming from compared to other literature I've been reading. He of

course

gave an overly broad non-technical answer, basically saying that they

don't subscribe to any approach. I didn't feel it would be

appropriate to persue discovering that he was full of crap in front of

a big crowd so I didn't bother asking any technical questions. The key

thing that bothered me was how he mentioned all

sorts of "modelling" of the room to choose treatment. Sure, they

measured a before and after, but I seriously have to wonder how much

measurement went on during the "build stage". In my short time playing

with room measurements I've learned that the data can be very

deceptive, which requires a certain level of trial and error to ensure

that the treatment is doing what you want it to do. Simulations are

great tools, but they fall very short of being sufficient to apply

directly to real life situations. But that's just how all engineering

is (even fields way unrelated to human perceptions and opinions). You

would think he would have at least mentioned some of the difficulties

with acoustical treatment and how they creatively overcome them. You

know, that fancy interesting crap that sets their company apart. Instead, he

left the impression that it was happy, easy, and that the models work. For

what it's worth, I've never been a fan of any Auralex treated rooms,

products or approaches. It wasn't until very recently that they started

promoting diffusion based products and they're still pushing that

stupid foam crap.

But I do agree that the disparities between various acoustics sources

is way unnerving. It seems the only thing everyone agrees on is that

treatment is necessary. I don't think it goes much beyond that because

most of the audiophile market already resists that notion. But once you

cross that barrier, I think it's then a matter of finding the company

that you like best.....just like how we all choose Klipsch over Bose.

Surely we don't get discouraged because they have different design

philosophies.

[anarchist]

I just wanted to point out that Mas was able to determine what the
treatment was like in that room without having ever been there! I think
that speaks volumes to his ability to interpret the data.













Would you happen to know which room at Klipsch was being used for this
case study? I have a feeling that it was the AB testing room, but I'm
not sure.

Dr. Who, your first point is exactly my problem. Mas has an entirely different interpretation of that data compared to Auralex. Who is right? Who is wrong? How do we know?

He points out they used 1 inch diffusion panels like it is unbelievable. They point out they used 1 inch absorption panels as well. Ok. So what? What is the significance of 1 inch?

I tend to think it may be the AB room as well because it was mostly under screened walls. However, the majority of that ceiling had the "metropolitan" diffusers everywhere, the walls had 3 inch diffusors added onto them, and it was specified the majority of the wall behind the screen was absorption panels.

There wasn't a room to my recollection which actually looked like the room pictured in the auralex brochure.

I tried their interactive room calculator. Basically, it just said to cover 50% of the room area with absorption, diffusion, and bass traps.

[DrWho]

Dr. Who, your first point is exactly my problem. Mas has an entirely different interpretation of that data compared to Auralex. Who is right? Who is wrong? How do we know?

Did you like the sound of any of the treated rooms there? If not, I might suggest seeking alternate approaches.

He points out they used 1 inch diffusion panels like it is unbelievable. They point out they used 1 inch absorption panels as well. Ok. So what? What is the significance of 1 inch?

The significance is the frequency range over which it is at best able to operate. 3kHz and above is a region over which the room can start to be considered large, and be treated as such. Basically, diffusion is a tool used to recreate a reverberant field. Absorption is a tool used to reduce a reverberant field. At various frequencies, we have either too much or too little reverb. Generally, it's too much reverb in the highs and too little reverb in the lower mids. Diffusing the highs is as pointless as using diffusion in a large auditorium.

I tried their interactive room calculator. Basically, it just said to cover 50% of the room area with absorption, diffusion, and bass traps.

I would place more emphasis on the ITD...

[HarryO]

I know I'm the FNG here on sound treatment but it would seem to me a "standard formula/calculation" being used leaves much to be desired. How do they know what I'm using and what my EXACT needs are. It seems pretty mathmetically unsound using their calculator with so many vairables involved.I'm sure their calculator can specifically sell me universal kits X how many to = profit vs room size only.

Like I said, I'm the FNG but my equipment issues and my room have specific needs. Can their formulas meet these needs?

I'll leave the numbers to you smart educated types and do the trial and error thingy until my ears say "OK" to me. I have to question formulas based on insufficient data at this point.

HELP

Harry

[mas]

Wow! Can we say "dead"?!

A

fascinating before and after ETC. One wonders just what they were

trying to accomplish as there are MANY significant issues still

remaining!

For the sake of brevity, I removed the remainder of mas's monologue.

The article specifies this is a great listening room based on the results of those measurements. Mas claims it is a disaster.

For us laymen, such contradictions do little to breed confidence.

They state the goal was to reduce reflections and smooth out the base response. The graphs appear to demonstrate that. Isn't the variance in the second graph evidence of the diffusion? Honest question.

Why the volume levels are different is a question mark? Normally, one would graph (or test) using the same test parameters to isolate the differences and make it easier to compare.

It would seem to me highly stupid of Auralex to use this particular example as their primary case study if it is so flawed. It seems even more unlikely a bunch of Klipsch engineers designing speakers would use such rooms if they were so bad.

I look forward to someone reconciling the differences in interpretation. Perhaps provide some references which support your position. I would much prefer to know I am reading something based on objective criteria rather than personal preference colored as fact.

As far as what is good or bad....you can like whatever you like!

As far as what is statistically desireable, this is easily correlated!

As far as a diffuse field, this is objectively verifiable in the measurements!

Compare this "after" ETC with the examples of a room with a developed semi-diffuse field posted earlier. Go look! Actually look! The diffuse field does not begin at a level at or below the level of the ITD - an interval designed to be anechoic!

Interpreteing the ETC is actually very easy - especially after you have had a bit of experience with them and develop pattern recognition.

As far as the "variance" establishing diffusion...I wish. It certainly does not. Gain levels being returned lower than an interval (IT) that is 'effectively absorbed' is not diffusion. And what is distinctive about a 'well-behaved' semi-diffuse field is the absence of defined specular reflections, reflections that are still anomalous and present and not diffused!

We've been through this before. If you desire to debate this based upon your assumptions and feelings, have fun. If you want to use generally excepted standards advanced by others significant in the field you are welcome to refer to what Davis, SynAudCon, Berger, RPG and many others have published. Those are the standards to which I subscribe. If you like a overly dry dead room (and some do), by all means, have at it.

What would be nice is a debate based upon fact and established validity (and AMPLE references starting with Davis & Patronis, both referred to and even posted in chapter form here!!!) and not simply the usually cult of personality debate which has ample precedence here. What I would like to see is some substantiation of the other points of view. I am making no attempt to advance my personal agenda. Rather I am sticking with the 'party line' that is WELL established in both the texts and the acoustics community. What is rather amazing to me is that, at this point in history a good 25 years after being established via AES, JAES, SynAudCon, and other places, that some are still debating this precedence.

Some evidently still chose to do so. I have no interest in this. Previous exposure and attention to such materials establish ample precedence.

And as far as interpreting an ETC...few who do not work with them routinely can do so easily (at least not initially). How many would have noted the substantial difference in the gain of the direct signal before and after. Start by explaining that. NO room treatment should have ANY effect on direct signal gain! And a comparison would be much more valid by comparing apples and apples. There is a difference in using the tool as a diagnostic tool versus using it as a marketing tool. I can't help but recall Jim Carey's ( a very prominent acoustician) oft mentioned question when he was brought in to shoot a system: "Are we buying or selling", as windowing, smoothing, etc. can certainly put makeup on a pig and make it more than presentable even in the light.

[mas]

He points out they used 1 inch diffusion panels like it is unbelievable. They point out they used 1 inch absorption panels as well. Ok. So what? What is the significance of 1 inch?

"What is the significance of 1 inch?"

I guess that depends upon who you are asking and in what context!

As far as acoustics and traditional absorption and diffusion techniques, this is significant. And as far as absorption and reflection and diffusion, for most methods, it is critical. Dimensions smaller than a wavelength are effectively invisible to that wavelength. And assuming even a 45 degree angle of incidence and a 1/4 wave level of sensitivity, I'll let you do the math! Class assignment: Calculate the effective frequency of the absorption and diffusion.

And Auralex is not (except for Russ's pArtScience line) employing any of Schroeder's math.

The frustrating thing here is that if we draw a conclusion based on much precedence and established science, someone always shows up to question the basic fundamentals. We can talk of quantum, but then there is always someone who comes up and questions how we know that there is any such 'thing' as an atom. (And the faces tend to be the same.)

How about starting by reading Davis and Patronis' Sound System Engineering. Then, if you like, I can point you to specific titles by Schroeder and Cox & D'Antonio. I don't have any issues with the 'existence of atoms'. If anyone does, before jumping in here and debating or questioning the interpretation of results that presume a knowledge of the fundamentals, read up and at least get up to speed with basic concepts.

[mas]

If anyone is interested, I will be glad to try to present a simplified process of addressing the 3 major aspects (realms) of a room according to generally accepted principles as espoused by the various sources to which I have referred far too many times to where I have been accused of name dropping!

I can certainly tell you how we do it and why. Objective evaluations are definitely possible.

After that, what you do and what you like is up to you. As long as you like it, you can enjoy whatever flavor of ice cream you like. And if you like anechoic chambers, hey... some like their steaks well done.

This (some of the debates) is beginning to feel like someone explaining quantum and having each time to verify and substantiate who's rules of quantum one subscribes, as if there are multiple schools of established thought in formal circles as distinct from someone's MySpace page!

Oh, and regarding the 1" thick absorption; assuming a 90 degree incidence, the lower effective frequency is 2387 Hz, and at a 45 degree angle of incidence, thus rendering the effective thickness of the material at 1.414", the effective frequency is 3376 Hz. We're starting way too high! This is anything But broadband absorption or diffusion. And 2" thick absorption at a 45 degree angle of incidence would still have a lower effective limit of ~1193Hz. ...all calculations assuming a 1/4 wave sensitivity.

[RFP]

...do the trial and error thingy until my ears say "OK" to me. I have to question formulas based on insufficient data at this point.

Harry

Ive got to admit that Im pretty much with Harry on this. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

More on my room The crummy little room is basically 12 X 21 with the standard (for mid-60s Texas) eight foot ceiling height. There is a tiny offset in the back of the room that adds a paltry 20 sq. ft., or so.

The Klipschorns are on the short wall, cause thats where everything fits. Actually, I built that wall (the one with the double doors between the K-horns) using ¾ plywood with ½ sheetrock over it its a pretty sturdy wall to snuggle Klipschorns into(!).

You can see that there is one and only one chair in the listening position (OK, I have no friends, cept maybe Seadog!). When I was getting the room set up, I sat in the chair and had my wife walk around the room holding a mirror flat against the walls anywhere that I could see the reflection of the Klipschorns, we installed drapes (yes, there are no windows behind all those drapes except for at the other end of the room there is one window). The drapes are pretty dense and are fully lined. I suspect that the diffusion is pretty good.

The entire back wall is draped and the drapes even turn the corner on one side of the room.

Of course, there is that 74 highly reflective piano just behind the listening chair, and it may be affecting the sound as I listen but I cant really name that as a problem.

I am eager to finish my little curved reflectors and see what that accomplishes (frankly, I dont expect that my 67-year old ears will be able to tell one whit of difference but, hey, the project is fun anyway).

Cheers, everybody!

Rob

Looking back from the "speaker wall"...

Looking toward the speaker wall... now, that's pretty obvious, huh?

[HarryO]

"Scarecrow: I haven't got a brain... only straw.
Dorothy: How can you talk if you haven't got a brain?
Scarecrow: I don't know... But some people without brains do an awful lot of talking... don't they" I like this a lot! hb

I guess I overstepped my education here by a quite a bit.

My question is, "Can they supply me with a Proper Kit based solely upon general input on their site calculator that will fit my room/audio needs?"

Your patience please and remember I am very simple.

Harry

[Deang]

I've been cruising the different treatment sites and I've just about concluded that unless someone comes to your house with the appropriate software, runs an analysis, and has enough of a brain to properly interpret and apply the data -- you can waste a lot money real fast. Hell, it's worse than caps!

I like this "diffsorbor" panel concept -- kind of like acoustic panels for those who don't know what they're doing.

http://www.rpginc.com/products/badpanel/index.htm

[mas]

I've been cruising the different treatment sites and I've just about concluded that unless someone comes to your house with the appropriate software, runs an analysis, and has enough of a brain to properly interpret and apply the data -- you can waste a lot money real fast. Hell, it's worse than caps!

I like this "diffsorbor" panel concept -- kind of like acoustic panels for those who don't know what they're doing.

http://www.rpginc.com/products/badpanel/index.htm

Amen!

RPG is a great reference for absorption and diffusion!

What I am posting is directly consistent with their principles - after all, Peter was fundamentally involved with Schroeder and SynAudCon too! We preach the same party line.

But, if you also look, please understand the very fundamental limitations of their modeling software! If you have questions regarding this, please call me!

Also, let me float this in a very general manner. If anyone has interest in measurement software, please contact me.

In fact, if you have any questions or confusion, PM me, its allot easier to address specific concerns directly instead of trying to address everything about everything in a general post! And this especially concerns basics..as we can quickly focus in on the basic issue and resolve it.

[Deang]

I have no interest in measurement software. I am however very interested in you coming out and fixing my room for free. Seriously, the software is almost worthless without the skillsets to read, interpret, and apply the data. Hey chief, that stuff's complex.

[anarchist]

I don't think it is possible Harry. You can download a file from them, enter in all you exact measurements, layout, etc. and they will provide a personalized report.

It would be nice if Mas provided the equations he used to calculate those items.

A "How to read ETC charts for Dummies" reference would also be good. An example of good diffusion vs bad diffusion graph would be invaluable.

[mas]

Try these diagrams. I have posted them at various times and places and have put them over in the Large and Small Room Acoustic thread...

http://forums.klipsch.com/forums/ShowThread.aspx?PageIndex=7&PostID=931603#931603

Note: The diffuse semi-reverberant field initializes AFTER a distinct Initial Signal Delay gap. It is decreased in amplitude by about 6 dB initially and decays at at an exponential rate thereafter. Specular reflections in the semi-diffuse field are to be moderated by diffusion - Keeping the energy in the room, but diffusing it. This provides a sense of the small space acting like a much larger space instead of a closet.

Exactly what the Klipsch room does not. The Auralexed Klipsch room is an extremely dry room that will sound very small and claustrophobic.

And why can I not get the hyperlink tool to link? The editing tools here, well, if you can''t say anything nice..... [^o)]

[HarryO]

"I don't think it is possible Harry"

I may not be the brightest bulb in the pack but i can't see how a "1 size fits all solution" could properly apply in every application just using a simple room size calculator.

I loved the "skyline" ceiling treatments and I'd like to have one just to look at if nothing else. Hey, It might work. I wasn't impressed with some of the "improvements" acheived but the crap looks cool if nothing else. LOL!

Thanks.

Harry