Echo Chamber Design.

Goodmorning forum! We are in the process of designing an echo chamber for our studio Montrose Recording in Richmond, VA. So far we have decided that a covered, unused space in the barn near the studio would be the best place to put the chamber as it 1) already has a concrete slab poured, 2) is covered from the elements, and 3) is in a quiet environment (other than the tin barn roof!). The space we're looking to construct on is 19' by 11'6 with a ceiling that slopes from 8' to 14' (see attached drawings for clarification). Realistically, the chamber will have to be slightly smaller than this to accomodate for the wall construction. Currently we are leaning towards an outer shell with staggered wall construction and an inner shell with a standard interior one as per Scott Putnam's REP article (http://www.prosoundweb.com/article/prin ... ho_chamber). My biggest confusion and what I'm primarily hoping to get some clarity on here is how to apply the Sabin ratio (2:3:5 by my understanding) to the real world dimensions of a chamber style construction with no parallel walls, or floor and ceiling? Is it done on an average? I have tried this formula several times with no conclusive luck. Any help or insight would be especially appreciated. And please let me know if any clarity is needed to be given. Our budget is a loose $2,000. Adrian Olsen Note on "chamber scan1", the braces are non essential and will be able to be removed..

"From the archives of the late, great Recording Engineer/Producer (RE/P) magazine comes a wealth of knowledge about echo chambers which first appeared in the July / August 1979 issue." A few things if I may. 1979 reverbs and spring reverbs, whatever they offered then have been far improved at this time in 2012. Based on that would it not be far much more economically reasonable to buy a few high quality boxes even some software that will do the same thing without all this hassle and with much improved results? "is how to apply the Sabin ratio (2:3:5 by my understanding)" Actually that is the Sabine ratio developed way back in the day (circa 1920) for room ratios, in general, by P.E. Sabine who was the cousin of the more notable W. C. Sabine who is the father of acoustics most noted for the absorption rates of materials. Alton Everest suggests in the Master Handbook of Acoustics that if you are bent on (my words) using a footprint with angled walls that deviates from a rectangular outline, then you have to take the volume into consideration.

"1979 reverbs and spring reverbs, whatever they offered then have been far improved at this time in 2012." Can we agree to disagree? I suppose I was a skeptic until we became owners of a 50s plate last year. IMO modern digital reverbs do not have the musical tail or the ability to sit in a mix like a real organic unit. I also love the sound of the chambers used throughout the 40s 50s and 60s - it's that sound and uniqueness that I'm looking for not a 'better digital reverb solution'. I really do appreciate your response, but have to admit that your attitude to not attempt the project at all baffles me a little bit... Actually that is the Sabine ratio developed way back in the day (circa 1920) for room ratios, in general, by P.E. Sabine who was the cousin of the more notable W. C. Sabine who is the father of acoustics most noted for the absorption rates of materials. Alton Everest suggests in the Master Handbook of Acoustics that if you are bent on (my words) using a footprint with angled walls that deviates from a rectangular outline, then you have to take the volume into consideration. Pardon my misspelling and thank you for the knowledge. I am not 'bent' on any kind of footprint, only asking this great forum for a minute's worth of advice for what in my opinion is a pretty interesting project!

"Based on that would it not be far much more economically reasonable to buy a few high quality boxes even some software that will do the same thing without all this hassle and with much improved results?" See how the above is formed like a yes or no question? We are not agreeing or disagreeing, simply me asking a few questions that seem pertinent. Anywho: I found a few things for ya to read, yep, more of it, and we are just getting started ;) http://www.gearslutz.com/board/studio-b ... ction.html Which leads to: http://www.gearslutz.com/board/studio-b ... amber.html Which leads to: http://malcolm.bignoisybug.com/rsdp/chamber.txt With many other pages in between. Hopefully this will get you going, maybe calm that attitude down that you think is coming from me ;)

"Based on that would it not be far much more economically reasonable to buy a few high quality boxes even some software that will do the same thing without all this hassle and with much improved results?" See how the above is formed like a yes or no question? We are not agreeing or disagreeing, simply me asking a few questions that seem pertinent. When I wrote "can we agree to disagree", I was referring to your statement "1979 reverbs and spring reverbs, whatever they offered then have been far improved at this time in 2012". Just to clarify.. Thanks for the links to the article and other forums, however I posted to this forum feeling that I have exhausted my online resources and wanted to tap into the knowledge base of builders here to see if anyone has had any first hand experience building chambers or at least 2c on what to do in our situation. I guess it just seems to me that there could be an addendum made to the public knowledge base on this issue, with, hopefully, our situation used as an example. So - given the dimensions we have in this location, are there any opinions out there for how to best orient the walls?

Not sure if this was in the 'reading' material ... but here's a link to a 'chamber' article: http://www.micworks.com/freeinfo/chamber.htm ... as a side note, I sure you're aware that many of the 'coveted' chambers built tended to be a guarded secret as to their design. Look forward to any good info you find ... :)

Yeah RJ, most of the links go to Malcom (the page you linked) or Putman...but the point was to sift through the people, and the stars they meet on the way thru this exploration. Concrete building with shellaced walls, that is what I have taken from it so far...makes since, mass like crazy which will be reflective in nature, and then just to add that extra decay time, shellac. It is not for the faint of heart and how to do and what to do, is different in nature to studio builds...to some degree. Heck yea, if I wanted one of those I would be fired up about doing it and would not even mind the obstacles...

ahhh ... ok. Somewhere in my hard copy library of AES journals, or RE/P archives [all in storage], there were a few articles on chamber builds. Dating back from the '70s & 80's. Couldn't imagine trying to dig those up :| Also agree ... working with great sounding chambers always brought a smile. Would LOVE to have one ... but I don't see that happenin' anytime soon for me :roll: No doubt that technology advances have altered many aspects [in most everything]. That said ... I'd utter words of encouragement to build one, just take your time and research like crazy. Might consider some type of 'acoustic modeling' program [if there is anything that would be useful and trusted to 'test' a design. Chambers are not that easy to structurally modify. I wonder if those free standing, 'refrigerator' housing you see at some large restaurants would be worth checking out as a shell ... with mods to the interior to alter wall angles :idea: :?: keep us posted !

to the real world dimensions of a chamber style construction with no parallel walls, or floor and ceiling?

Just adding my US$ 0.01 (don't think it rises to the level of 0.02!). I'm not convinced that non-parallel would be the best way to go. Sure, it might spread the modes around a bit more, perhaps evening out the spread, but they'll still be there, ans still be problematic, coloring the "signature" of your chamber. Especially the tangentials and obliques. So predicting the resonant behavior becomes a job for FEM/FEA, and can no longer be accomplished with the simple tools and simple equations: Wouldn't it be better to keep it more or less rectangular, and adjust the dimensions for a good ratio? Yeah, Everest does say you can average to a certain extent for low angles, but Eric Dessart (I thin kit was Eric, but I might be wrong) has pointed out that nobody really knows much about that, or how large/small the angle has to be before averaging is no longer valid and FEM/FEA becomes the only realistic option. I've also heard of using movable barriers in chambers, to change the "sound", but can't find any info on that. Have you considered going down that path? Maybe some kind of massive, reflective gobo-style "wall on wheels" that could be moved around, to change the character? Maybe also install movable transducers, or multiple transducers on a patch bay.... Just some wild, off-the-wall ideas for you. - Stuart -

http://www.micworks.com/freeinfo/chamber.htm "Since it is the function of a chamber is to generate standing waves, the normal rules of acoustics don't apply. For that reason the actual shape of the room is immaterial. I recall one that was built into the space left under a staircase. It was short, but the sound was first rate. Square, cubical, triangular and round rooms all work equally well," The general items we consider do not apply as I am coming to understand it

Thanks for the additional links ! Appreciate all additional knowledge. Now that I think of it .... Heck .... I COULD have used my new Control Room as a chamber :shock: ... that was BEFORE all the corner traps, panels, and clouds were installed :P :shot: alright .... sorry :oops: