Ethan I have a question...

[JustaBassist]

...about your website. In your website about making inexpensive bass traps I have bought some fiberglass rolls to make a 30"x48" bass trap form 1x8s. Well the rolls are 3 1/2" think by 15" wide, so I would cut 4 15x48 peices and place them 2 wide and 2 deep with the face side facing the front and a face side facing the back. Would that be close to meeting your standards? These bass traps will be used in my control room/home theatre/bedroom.

 

[Ethan Winer]

JAB,

> Would that be close to meeting your standards? <

All of the traps I show in my various articles use rigid fiberglass, not the fluffy type. Fluffy fiberglass can work too, and you can even leave the bales as is and stand them up in the corners.

--Ethan

 

[Mind Riot]

The thing is that rigid fiberglass is much more dense that the fluffy stuff, so you'd need to use more of it to get the same results. I seem to recall Ethan saying in his Acoustics FAQ that one or two inches (can't remember which) of rigid fiberglass would work about the same as a foot thick of regular stuff. So if I was in your position I'd do what Ethan said and put some big bags of the fluffy stuff in the corners.

 

[JustaBassist]

Thanks a lot guys, I have plenty of fluffy bales to work with. Would you also reccomend putting fulffy stuff in the peak of ceilings?

 

[Mind Riot]

Thanks a lot guys, I have plenty of fluffy bales to work with. Would you also reccomend putting fulffy stuff in the peak of ceilings?

Yeah, try stacking the fluffy bales in as many of the room corners as you can, and stack them all the way to the ceiling. The low end tends to build up in the corners most, and the trihedral corners are the worst (trihedral meaning where three surfaces meet, like two walls and the ceiling or two walls and the floor). If you can swing it, after the room corners are all treated, putting treatment in the floor/wall and wall/ceiling joints or ceiling/ceiling joints will help too. But the biggest culprits to go after first are the trihedral corners.

 

[JustaBassist]

Now I have another question concerning bass traps. I'm curious to ask about making something like a bass buster, either the columns of the rectangle shaped column. By doing this I though about just making a base and top with a rod (1"x1") verticly going up the center. Then wrapping the fluff fiberglass tightly around the center poll until it reaches a certian radius from the poll, like 6", 8 inches. To finish it off by putting inexpensive cotton fabric on it. So this design would be inexpensive and portable. So would placing 3, 4 of these columns at different heights in every corner do a fairly decent job of being a bass trap?

 

[Ethan Winer]

JAB,

> I'm curious to ask about making something like a bass buster, either the columns of the rectangle shaped column. <

The key to all absorption is using enough absorbing material and putting it in the right places. Yes, it's as simple as that.

--Ethan

 

[RICK FITZPATRICK]

The key to all absorption is using enough absorbing material and putting it in the right places. Yes, it's as simple as that.

Yea, but determining HOW MUCH absorption you need, and at what frequency is NOT so simple. Unless of course, you want an anachoic condition, or you simply using a broadband approach. But what if you have a 40 x 60 x 14 room, with concrete walls, open trussed ceiling with exposed 2x6 pine T&G roof membrane, maple floors, 2 couchs, 1 12x18 rug, and you WANT a RT60 of 1.5 seconds and a DIFFUSE soundfield at a live end, and a dead end with an RT60 of .5 with gobos for vocals and live stand up bass?
fitZ

 

[gvarko]

Huh?

But what if you have a 40 x 60 x 14 room, with concrete walls, open trussed ceiling with exposed 2x6 pine T&G roof membrane, maple floors, 2 couchs, 1 12x18 rug, and you WANT a RT60 of 1.5 seconds and a DIFFUSE soundfield at a live end, and a dead end with an RT60 of .5 with gobos for vocals and live stand up bass?
fitZ

Speak f-ing english....

 

[Mind Riot]

Yea, but determining HOW MUCH absorption you need, and at what frequency is NOT so simple. Unless of course, you want an anachoic condition, or you simply using a broadband approach. But what if you have a 40 x 60 x 14 room, with concrete walls, open trussed ceiling with exposed 2x6 pine T&G roof membrane, maple floors, 2 couchs, 1 12x18 rug, and you WANT a RT60 of 1.5 seconds and a DIFFUSE soundfield at a live end, and a dead end with an RT60 of .5 with gobos for vocals and live stand up bass?
fitZ

Well, in that case you would OBVIOUSLY want to use 8.42765 inches of super absorptive polysorbatiackrium mounted exactly one fifth the troublesome wavelengths' square root opposite all the trihedral corners. Of course, you would have to be extremely careful about where you place the atomic cerebral enhance-o-tron or else it could create a time paradox, resulting in a chain reaction that would unravel the very fabric of the space/time continuum and destroy the entire universe!!!!

Granted, that's a worst case scenario; in fact the effect may be very localized and limited to merely our own galaxy.

 

[RICK FITZPATRICK]

Speak f-ing english....

I'm sorry if my use of Acoustics 101 terms is hard to comprehend. Let me explain.

RT60- REVERB TIME = the time it takes for a sound to decay 60db.

Absorption- In terms of sound energy, it is the dissipation of this energy by a transducer into heat. There are different forms of transducers. Resistance absorbers exchange this energy by placing a resistance to the movement of air molecules via fibers. Usually, fiberglass or mineral wool. Owens corning rigid fiberglass is an example of a resistance absorber. Panel absorbers, use two methods. The resistance to flexing of fibers within the panel, and the air spring behind it at resonance. Hemholtz resonators use resonance (I believe)within a closed container to dissipate the energy at a frequency determined by the width and depth of a of an air column at the entry point. Imagine a bottle. Beer bottles can be considered a Hemholz Resonator. Fill a box of standing bottles, and the necks form the same principle as the holes in pegboard, or the slots in a Slat/Slot resonator.
Diffuse sound field(consider it impossible in small rooms)
Here are a few characteristics as read from Alton Everest's handbook of Acoustics.(forgive me for reproducing this Mr. Everest, it makes no money for ME )
1. "The frequency and spatial irregularities obtained from steady-state measurements must be negligible."
2. "Beats in the decay characteristic must be negligible."
3. "Decays must be perfectly exponential, i.e., they must be straight lines on a logarithimic scale"
4. "Reverberation will be the same at all positions in the room"
5. "The character of the decay will be essentially the same for different frequencies.
6. "The charachter of the decay will be independent of the diretional characteristics of the measuring microphone"

Gobo- Device for the isolation of instruments and vocalists. May have a reflective side and an absorption side. Usually mobile. Comes in a variety of sizes and configurations.

Live end- Usually the end of a room lined with diffusers, lots of reflective surfaces, and a long RT60. Usually used for the recording of acoustical instruments or the backfield of a live performance venue, such as a concert hall. Also describes the rear wall of a proprietary and licensed control room paradyme called Live End/Dead End.
Dead End- Usually the end of a room lined with lots of absorbers to limit reflections and lower an existing RT60. Usually used for recording Rock music, or other instruments requireing very little reverb and to control comb filtering.
May also be somewhat diffuse by patchwork placement of absorbers. Also used to define the front end of the Live End/Dead End paradyme, where by the front of the control room is mostly absorbers to reduce early reflections.

And now for my disclaimer. I am NO acoustics expert, professional or even somewhat educated practitionor of, nor am I experienced in the use of, construction of or placement of acoustical materials or devices. In laymans terms, I am simply just like you, only I have read a lot. THATS ALL.
fitZ

 

[RICK FITZPATRICK]

Well, in that case you would OBVIOUSLY want to use 8.42765 inches of super absorptive polysorbatiackrium mounted exactly one fifth the troublesome wavelengths' square root opposite all the trihedral corners.

Thankyou Mr. Mindriot for your professional consultation. Your advice will be taken into consideration. Except for one thing, You gave NO indication in Sabines how much absorption will be required. Nor did you define the construction method for the production of a diffuse soundfield. Please do not hesitate as your reply is eagerly anticipated.
fitZ

 

[JustaBassist]

Rick-
Great stuff BTW.

Ethan-
Well as I continue reading I am learning a LOT more in little steps of D.I.Y. bass traps. I'm again curious if wrapping 705-FRK around the inside or outside of those cement carboard columns (I dont know what they are called) used for setting in posts for a deck. I believe the material is about an 1/8 to a 1/4 inch think. Would the air space inside benefit for a bass trap?

I'm just trying to come up with different ideas for bass traps so I can limit myself with making panels.

 

[Mind Riot]

Thankyou Mr. Mindriot for your professional consultation. Your advice will be taken into consideration. Except for one thing, You gave NO indication in Sabines how much absorption will be required. Nor did you define the construction method for the production of a diffuse soundfield. Please do not hesitate as your reply is eagerly anticipated.
fitZ

I guess they don't have humor where you're from?

Please don't allow my meager attempts at levity to stop you from dropping as many acoustics terms as possible to make yourself appear smarter than everyone else.

 

[RICK FITZPATRICK]

Hey Justa bassist, get off your high horse. In the first place, I was responding to Ethans reply. THAT my friend WAS levity, but I guess it went over your head. And then Mindriot decided I was being something other than funny too. So I tried to explain what the terms ment. I get the direct feeling around here that no one wants to LEARN anything, just crap on information that might do them some good. And here I thought this was a studio building forum. Hmmm.

 

[Mind Riot]

Hey Justa bassist, get off your high horse. In the first place, I was responding to Ethans reply. THAT my friend WAS levity, but I guess it went over your head. And then Mindriot decided I was being something other than funny too. So I tried to explain what the terms ment. I get the direct feeling around here that no one wants to LEARN anything, just crap on information that might do them some good. And here I thought this was a studio building forum. Hmmm.

I certainly apologize if I took your post the wrong way. Subtle humor doesn't always come across in text. As I was reading it it seemed to me that perhaps it was humorous, but the last couple sentences seemed a bit more of a put down. For future reference, one of these sometimes comes across as disrespectful, and it's tricky to know what was intended. We don't have the benefit of body language, facial expressions, or voice inflections in these forums.

If in fact I did take it wrong then I certainly apologize.

 

[RICK FITZPATRICK]

Hello Mindriot, not a problem. Justabassist, excuse me for hijacking your thread for this little rant, but let me clear something up here. I've been posting on this bbs for 4 years now, and have posted PLENTY of good help, and I think I've gone out of my way to help enlighten people with what I do know, not that it is expert advice, but I believe I've also researched enough to know when I shouldn't stick my neck out too far. And as you probably know, I also inform them of my disclaimer. I also have my bad moments, and my attempt at humor, which not all people may appreciate. Sometimes, I'm borderline sarcastic, and sometimes I'm a downright prick. I know. But at least I can admit it. What you will find though is a genuine attempt to help most of the time. Yea, sometimes I get friggin tired of trying to figure out what people are asking and even the way they ask, and I say so. And sometimes I spout off with an attitude. So what. Sometimes people deserve it and sometimes not. I'm not perfect, sometimes I make mistakes. But MOST of what I have posted here, is honest, helpful and sincere.
Lately, for reasons I won't go into, my attitude got the better of me. Unfortunately, I let it influence some opinions here that shouldn't even been said. I AM sorry about that, but thats life. Nothing I can do about it now except make up for it. Hence my reply here. In that regard, please let me explain.
Ethan posts here, and many other forums. In fact, he is probably the most visible person on the net in regards to Acoustics, sound, recording and other interleaved subjects, and that is fine. And please don't think I'm making an issue of anything, as he has helped people far more than I. I respect Ethans opinions as they are based on long term experience. However, in full view of members of various forums, there is an ongoing professional dispute between Ethan and other parties regarding subjects I will not discuss here, cause basicly its none of my business. However, since this disagreement has two sides which are publicly expressed, I have my own interest in following it to its conclusion. The reason is simple. Opinions are one thing. Scientific proof is another.
Since I became interested in Studio Design, acoustics became a focus of this interest as it IS the point of Studio Design. But as I soon found out, acoustics is a science. And as a science, years of education and graduation from university are the means by which one obtains credentials as proof of his knowledge of this field. It is this credential by which one earns the title of Acoustician as it is PROOF of "expert" status.
It is this professional status of other parties which gives credibility(at least to me) to the opinions expressed in opposition to Ethans view. Once I read both sides of the argument, I began to sincerely question some basic assumptions. One, of which, is taking the word of a "self" proclaimed "expert" as credible "truth", which is precarious at the least, and a setup for possible loss of trust should one become enlightened to other information that proves all is not what it appears to be. Not that this has happened. On the contrary. However, in light of the credible argument on behalf of Ethans opponents, I believe there may be something to it. Regardless of Ethans attempt to explain this other persons animosity towarts Ethan as a personality flaw. Hence my own display of displeasure with certain practices that Ethan uses here as well as elsewhere. Of which we had a discussion or two here, and promply resolved to my satisfaction. Not that I am the arbiter of HR policy. But I think I am alowed to question certain things just as people have suggested that I be removed as a member for my outrageous attitude sometimes.
Well, the point is this. When I read certain opinions of Ethans that I don't totally agree with, but yet have no direct proof of inaccuracy, I do the next best thing. I ask for further depth of explaination, in the hopes that some piece of information may widen my own knowledge of the subject at hand. Trouble is, when I do this, I place myself in a precarious position, as my knowledge is not as deep as Ethans, so mostly I try to use a little humor to provoke a response. Hence my reply today, although, I guess my humor wasn't as keen as I thought. Ok guys, thats about it. Another verbose and meaningless ramble about nothing. I just thought I'd try and clear this up.
Cheers
fitZ

 

[Ethan Winer]

Bassy,

> I'm again curious if wrapping 705-FRK around the inside or outside of those cement carboard columns <

Nah, just use 2x4 foot flat panels, 3 to 4 inches thick, and be done with it. As soon as you put something rigid in front or behind, you just harm the performance.

--Ethan

 

[Ethan Winer]

Rick,

> I respect Ethans opinions as they are based on long term experience. <

Well that's something positive.

I don't know what your point was with the rest of that, since all I did was try to help someone as best I could. But I don't need more people accusing me and impugning my knowledge and motives. If you'd prefer I stop helping people here, just say the word and this will be my last post.

Please note well that I have never claimed to be a degreed acoustician. I do have a lot of practical experience with all aspects of audio, and I know an awful lot about bass traps.

Did you know that many professional acousticians - with degrees and everything - do not accept that rigid fiberglass straddling a room's corners is a viable way to trap bass? I've also seen professional acousticians dispute the presence of comb filtering at predictable distances from a reflective wall. I am the very last person to dismiss the value of a formal education. But that's no guarantee of being right. Somebody has to graduate last in their class!

> When I read certain opinions of Ethans that I don't totally agree with, but yet have no direct proof of inaccuracy, I do the next best thing. I ask for further depth of explaination, in the hopes that some piece of information may widen my own knowledge of the subject at hand. Trouble is, when I do this, I place myself in a precarious position, as my knowledge is not as deep as Ethans <

This is exactly the problem, and you are not the first person to say, basically, "I don't know enough to say that you're wrong, but others say you are, and they have a degree, so you must be wrong." Sheesh. Actually, as far as I know, none of those people who constantly try to belittle me have any degrees at all. Do you know for a fact any of them have degrees, and what type of degrees?

Then again, consider Dr. Laura. Yeah, she's a doctor all right, but not in the field she offers advice.

A degree proves only that you went to the trouble to learn how to answer some questions on a test. It doesn't mean you know how to solve problems, or know how to think logically. Again, I am not demeaning the value of a college degree. My father was a doctor, and my wife is now on track for a Ph.D. But don't be like (you can probably guess who) and wrongly believe that anyone with a degree is always to be believed over anyone without a degree. At some point you - yes you Rick - have to sort through the facts yourself to see what makes sense and what doesn't. To blindly believe someone solely because they have "credentials" is a mighty dangerous thing.

--Ethan

 

[RICK FITZPATRICK]

If you'd prefer I stop helping people here, just say the word and this will be my last post.

Ethan, with all due respect, don't lay that on me.
Your predicament within the community was none of my doing, and I take no responsibility for it whatsoever. I do however, owe it to myself to listen to other PROFESSIONALS in the field, regardless if they have a degree or not. Especially when they back up thier accusations with what I feel is a valid argument. Right or wrong, I still read it, so I can realistically research other opinion, and draw my own conclusions. Besides, I never accused you of anything myself. Far be it from me to do that as I'm so far removed from science it would be not only pathetic, but humorous as well. Hence my last reply to you. So lets set the record straight. I've already said that I respect you, and you have helped far more people than I. I just question where the truth REALLY resides.
As far as bringing your dispute to light here, it was only to explain my point in replying to what I felt, is your oversimplified view of absorption within that statement. You have to admit, your self proclaimed "expert" status, is a little presumptuous, don't you think. Yea, you may have experience at this stuff, but let me tell you something. From what I've read in the last few months, it APPEARS even long term acoustical analysis STILL hasn't proved what the hell is going on with absorption. I mean, comon pal, when I read accredited acousticians talking to each other about not having a clue yet what causes the actual "edge effect", whereby a given square footage of absorber is cut into patches, and when measured, they get up to EIGHT TIMES the absorption of the same square footage in one piece. That tells me something. And I'm not talking about absorption along the edges either. Actually, after reading as much as I have, I've reached the conclusion that the science of acoustics really hasn't proved all that much since Sabine. I think they are still scatching their head about a lot of stuff that I've been reading about since the 80's! In fact, let me give you an example that even Eric can't answer. There even appears to be a conflict of opinion, which in my mind, opinion shouldn't even exist, as it is presented all over the place as fucking scientific fact. And that is diffusion.
When I first became interested in Studio Design, I bought Alton Everest Master handbook of Acoustics. As you are probably aware of, within the chapter on Diffusion, he presented what at the time, were new theorys in the application of random number sequences to the construction of diffuser devices. He illustrated the concepts, the math, the tests, the design, the layouts, and even pictures of these in actual studios. Even the description of a licensed control room design Paradyme called Live End/Dead End. Now, I don't know about you, but when I puchase a book written by a credentialed person such as Mr. Everest, I tend to believe what they have to say. Especially when presented in a "scientific" context such as exists in that book.
When I saw this stuff, I was elated, as here in black and white, was the new science of Studio Design in all its glory. Everything was there. I couldn't wait to build my studio. Ha! Fast forward 10 years to when I finally had a space to begin my journey. Low and behold, I discovered HR and began to piece together the construction secrets of isolation and began to see how others were putting applied acoustics to work in their studios. Trouble was, all of a sudden I began to notice a distinct change in overall design and acoustical construction. No where did I find any mention of diffusion, or quadratic residue, or prime numbers etc. Zero, Zilch nothing.
It was at this point that I began to ask questions in regards to the non existance of diffusers in current control room design dogma. That was when the shit hit the fan. John Sayers was the first to confront my belief system reality. He told me flat out, "they don't work, and I've seen miles of em torn out in studio remodels"!! ARRRRRRRGGGGGGGGGGGGGG!!!!! Where the fuck had I been
Ok, its been 4 years since joining here and let me tell you something. I've asked the same questions at least 20 times on every forum I've encountered. And to my amazement, the answers I have recieved are absolutely bewildering. Again, I don't know about you, but I don't buy this crap of science changing on a whim. EITHER it WORKS OR IT FUCKING DOESN"T!!
I actually went so far as to quote the page numbers of the pictures in the book, and point blank asked the members of Alt. Physics Acoustics.com this question.....SMALL ROOM DIFFUSION >>FACT or FICTION. The first response I got was from Eric. To my surprize, he actually admitted to being astounded at Mr. Everests book. Here is his reply...

I just had a look. At a first glance they are a Hibrid between a Schroeder diffuser and whatever.
I don't like to discuss those pictures.( he don't want to discuss it )
Personally I shouldn't think about creating a room like that. (hmmmmm)

I'm in fact classically trained in physics and acoustics.
The first time I ever saw Everest books, I thought I had a wrong book in my
hands. (WHA THE FU..... )
For me in the studio world, the magic surrounding acoustics is much stronger
than I like.
What one nowhere describes is that Schroeder diffusers are partly
(narrowband) 1/4 wave silencers too.
So I leave it like that. (this are endless discussions with subjective
arguments)
Even with free MDF I shouldn't build such a room as shown on those pictures.

I was stunned. Here is an acoustician stating he couldn't believe this was a book on acoustics, written by another accredited acoustician. F U C K M E!
Here is Angelo Campannelas reply:

I have no idea what MDF is, but I suspect that it is an absorber.(geeeeeezus!!!)
A
little bit of my home-spun philosphy on "diffusion":

1- Diffusion, among other things, depends on the variability if acoustic
impedace across a surface.
2- An absorber placed on a hard surface changes it to be a place where
sound is absorbed instead of reflected.
3- Ergo, places where patches of sound absoption are placed provide a
location where the sound impedance has changed and therefore can act as
a defacto diffusing element of size equal to its dimensions.

> it for nothing. Although, I own a woodworking shop so it would be
> nothing to build IF I understood the math involved.

4- Therefore, one need not always build awkward objects of wood, plastic
or metal to affect some diffusion: As long as I need or can tolerate a
fair degree of absorption in the subject room, I can place absorber
patches at a variety of locations, and of variable size, and get a very
good start at diffusion.

CRAP. That did it. I was so mad I burned the book. Talk about pissed off? To this day, I now don't believe a fucking word about this stuff. Yea, I talk about it here. And I still read. But you know what? I now believe this stuff is filled with so much snake oil you could lubricate the Titanic. Hence my listening to others who question TESTS, OPINION, PRODUCTS and netfact. I've pretty much given up on giving advice when it comes to acoustics Ethan. Because frankly, untill I build my room, I can't offer ANYTHING in the way of practical experience cause I've NEVER DONE IT!! And now, from what I've read, regardless of what people say, there IS contridiction all over the place. That is why I opened my mouth cause basically, I don't even believe you or anyone else anymore.
Well, I hope that explains my negative view of this whole damn thing. Right or wrong, this episode regarding diffusers left a real bad taste in my mouth, as I spent a great deal of time researching, designing, analyzing, dreaming and asking questions, only to discover that science or not, some people are just plain full of shit, even if expert, licenced, accredited....doesn't mean jack shit to me anymore.
fitZ