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Post by julian on Nov 21, 2020 16:54:42 GMT
Hi all!
I am writing here in order to see if what I have been reading about small room for recording and control rooms is right, regarding the problems of small room.s
This is not a "final" approach, as every room should have their own features, in the end, but this is an initial approach.
I have three assumptions : first, trying to avoid rectangular walls would reduce the intensity of the room modes, although not eliminating them, will certainly make them smoother. second, if these walls are made out of some kind of variable gypsum board with different widths (some parts 15, some parts 15+15) and different distances to the heavy wall (away from 50mm, minimum rockwool, to 200mm, air + rockwooll), that would make an initial bass trapping of the room. Third, is that I assume it is not enough bass absorption, as we're looking to very low RT in the room (I know it is not the right parameter) so we need more absorption in forms of other bass traps.
So here my questions:
1)Are my first two assumptions right? Right starting point : non parallell walls (maybe just one, or two, 5-10 ยบ difference), and gypsum with variable cavity to initial bass trapping.
2)Besides trapping with extra membranes (could be a corner with a fine sheet of wood?) and thick 10-15cm porous absorbers that are open to sound on all sides, away from walls 30 cm for example, and eventually a very wide range Helmoltz Absorber, is there anything else that can be called a "bass trap"? Is that the right approach? A more or less regular distribution of absorption, focusing on some strategic points will be fine?
My fear is that there is some kind of more complicated system behind the absorption in some bass traps, which I feel I cannot calculate and I don't understand the principles it will be working with. Something that changes the performance of absorption. Is there any way to avoid mid-high absorption of wool besides helmholtz ressonators? The only way to boost performance is strategic positioning, rather than "treatment"?
3) Non absorptive zones, can have just an irregular shape? Broken triangles, stone-like, sudden change of materials, mixed absorption/non absorptive materials... just avoiding schroeder diffuser designs towards something that is not maybe as perfectly diffusive, but is rather just irregular? Just to be, design-wise, open. Anything except concave surfaces, of course!
Thanks everyone!!
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Post by Deleted on Nov 21, 2020 20:13:14 GMT
It is way more complicated than you think. To really understand acoustics, it takes years of trial and error and learning. Forget that angling walls thing. These desings are complex(you really can't predict and calculate easily), and usually used in acoustically large spaces, concert halls etc. + 5to 10degrees does next to nothing. Why you dont want schoreder diffusers? Do you have room(s) that you are about to do the treatments, if so, dimensions? For the porous absorbers, play with these: www.acousticmodelling.com/porous.php www.whealy.com/acoustics/PA_Calculator/index.html Basically both do the same.
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Post by julian on Nov 22, 2020 13:22:45 GMT
Hi Pasim,
Of course it is more complicated, but I want to understand how solutions work, and I make my bet on what I know. I dislike not understanding the scientific principles of every solutions, as I think acoustics of small rooms is sometimes more a business than a science. In the end...there's always a product someone wants to sell you, and it's the magic solution. Opposite to this, auditorium acoustics can be performed without "the products" rather than commonsense and understanding of physics.
Besides this, my post is a result of a lot of research before assuming this. Reading articles, books and the articles they cite to base their scientific statements, and seeing studios. I don't think one has to make hundreds of mistakes before getting things right, one has to try to see what has been done and has worked, and what has not. What is absolutely surprising, is that there is no book explaining how to treat systematically bass absorption.
Regarding angling walls, how do you justify they don't work? Can you tell my exactly why, and what scientific evidence can you show to me? . I mean,as I have studied, BOTH possibilities work, and unless someone shows me scientific evidence I won't take anyone's word. I need facts, diagrams, tests trials, whatever.
Room is 2,25 - 6,40 - 3,30
Regarding Shchoreder diffusers, they're not compulsory, aren't they? I know they are a great scientific advance, but I just don't want to feel they're the one and only solution.
Which gets to my point: understanding how to solve a room is not about buying products but knowing how they work, and that's what I am trying to understand.
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Post by julian on Nov 22, 2020 13:29:31 GMT
And thank you for the web,I already knew the formulas, but it is very handy!
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Post by rock on Nov 22, 2020 18:43:48 GMT
On this forum, we are not selling anything so we are interested in science and not business. Ethan's Real Traps are for sale but he has set up this site for those DIYers and there's no business in that except good will. AFAIK, members don't get paid. We do discuss ways to systematically deploy bass absorption. It boils down to placing them in the typical places, testing, analyzing, adjusting and repeat. If you take the time to search and read threads you'll find tons of info right here. Regarding angled walls: They will do "something" so "They do Work" but what does that mean? I agree with Pasim saying "forget about angled walls". Here's a video I just found for you that I think does a good job explaining the reasons. www.acousticsinsider.com/parallel-vs-angled-walls-reduce-room-modes-and-flutter-echo/#:~:text=Are%20you%20building%20a%20new,parallel%20walls%20or%20angled%20walls%3F&text=Because%20room%20modes%20only%20build,away%20from%20the%20listening%20position. Schroeder QRD 1D diffusors are worth strongly considering if you need/want diffusion. There are other solutions and AFAIK we are not selling anything on this site so you are free to build or buy any design of your choice. If you have read all of Ethan's material, I think you'll have a good idea of the things we understand...or at least are trying to...
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Post by julian on Nov 22, 2020 20:04:04 GMT
Hi rock,
Thank you for your answer!
First of all, Ethan's material is one of the most comprehensive on the next, by far. And I already thank him for that.
I wasn't referring to his traps, I am just wondering that sometimes the "same solutions" as rectangular walls are recommended, because people know how their solutions work in this geometry. If feel that people tell you to make rectangular walls because they know to solve them, but I think rooms are ALWAYS complicated, so many things in a room start to appear in the end, so the modes, I feel, don't end up mattering that much. Who can REALLY calculate something that is not perfectly rectangular without the finite element methods?
I don't want to get rid of the bass traps, I just want to have a good starting point with angled walls and membrane absorption. And considering the utility of angled walls as both reflective and variably absorptive surfaces (as they are angled, the cavity is variable, and thus it must have a wider range of absorption), I felt it was a possibility I wanted to check out. Say, it is preferrable to an undamped rectangular room.
And regarding bass traps, I have never seen an exact configuration of one. That's why I was asking, nothing more than that....
I saw that video! Interesting, but short! It made me think, of course, but I think he doesn't focus on a probably professional studio.
Schroeder diffusors are great indeed. I again, not meaning to sell anything, but if you recall a book like Alton Everest, is constantly talking about products, mainly RPG, at that time. I just think that one can make them or buy them, but I see them as a "product", despite their scientific accuracy. When everyone recommends them, it is just strange to me.
I will read more things on the forum!
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Post by pingpangpong on Nov 23, 2020 4:24:59 GMT
Hi....well first I'm not very scientific and probably go against half the things I think I should do myself, but do get excited by building things, and finding solutions, it sounds like you have already read enough to know what you should be doing, so think maybe you should trust yourself and start. This is just my personal approach so I can't help with taking readings...at present I'm in a ridiculously small room as in my head is almost against the wall and the speakers are on the opposite wall I have thrown some home made panels up but moved onto other jobs as I'm intending on building another room at some point....but I was very surprised....it's even brought details out of my speaker I've not heard before! That's why it put me in a stop gap because I'm in no real rush to move now....it's doing the job fine until I move onto more detailed sound. I can tell what's wrong though, but I can ignore that for now as I need to strip all my equipment out to make a little mess.....so that's my other point...when it comes to building its weather you are doing it yourself and how much time you have...I've always lived in a building site building as I go and moving between finished rooms but always writing music in between getting to hear each room from a mixing perspective.....I just built a new drum room and it's now ruined my perfect size mixing room! But for practicalities and inspiration it's perfect.....it will be used for more than just drums....but that's what I'm calling it atm. So this probably hasn't helped you at all! I sometimes know what I'm going to do regardless of anything but do need the odd nudge in doing it.......I slightly agree with pasim but wouldn't say loads of mistakes.....but if you get so far and you have 10% fixing weak spots and adjusting that's not such a bad thing....if I was you I would decide how much room you are willing to loose to absorption and frame it out to that....if you did angle your walls you could build your framework out from the middle which would give you ready made bass traps as voids behind your frame that you could fill.....so all your treatment would be behind the framework.....that's going to make your room smaller but saves having to fix from the inside.....that's what I was going to do but didn't! Only because I wanted to keep a semi lounge feel to what now is my tracking room.......but I will be taking this approach when I build my final mixing room...then I will probably have the problem of adding back some reflections! Another reason I didn't go for fully absorbed.....a wanted something a bit more natural but without so many nastys....also I would say proofs in the pudding if your building for writing your own music.....I'm not trying to write modern sounding music....or write hits or sell units....and I'm making a lot of assumptions and compromises with my rooms because I want them for more than one thing.....I'm happy to take the small bit of knowledge I've picked up and take readings later and if I've made major blunders then bad luck for me.....but I'm confident It won't deter me from the writing....for me the creativity part rules....so unless your client based pro studio I would make what you want.....hinged walls on rollers was another idea I was playing with.....but think I have a small addiction to making things....but pretty sure it would come in useful and interesting for experimental purposes.....so sorry for all that useless informations! I wanted to say something but end up rambling......
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Post by Hexspa on Nov 23, 2020 7:15:35 GMT
Keep it simple: use a lot of broadband absorption.
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Post by julian on Nov 23, 2020 13:32:01 GMT
Guys! Thank you for your answers! Yes, I think broadband is the simplest... I asked this in gearslutz. My only fear of it is too much mid-high, high...so, is a solution to this, a fine polyethilene sheet?
PD: Pingpangpong I really liked your stream-of-consciousness approach!
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Post by julian on Nov 23, 2020 13:32:28 GMT
(a fine polyethilene sheet sorrounding the wool)
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Post by Hexspa on Nov 24, 2020 1:37:34 GMT
Don't surround it. Just on the side facing the room. It reflects above about 1kHz and increases low absorption due to a membrane effect. I'd recommend putting it on only the top and bottom quarter of each panel so that the center is available to absorb high frequencies. Alternatively, you could just not apply it to the RFZ and then selectively apply it to the remaining panels.
Honestly, I have to say, after being fascinated by acoustic treatment for a decade, I looked around my room and thought, "This is so simple!" For real, it's just a bunch of soft dead weight. It makes total sense: kill the influence of your walls. It's tragically funny how deep people get into it when all they need to do is buy a bunch of insulation and stick it in the room. Despite this being an oversimplification, it's far closer to the truth than the overcomplications many of us get lost in.
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Post by julian on Nov 24, 2020 7:54:19 GMT
Hi Hexspa,
Thank you for your answer!
I will probably agree with you in the future, but I always think one ends up simplifying things after one has studied a lot and worked with it. Trying a simple explanation requires discarding the complex ones...so that might have taken you time!
I just didn't picture a simple solution for bass traping, as this was a problem I have never approached.
I've read, and I never quite saw how they're constructed. So many things in the market, so different between them...
I was proposing plastic over the wool as I assumed wool alone would have a bad balance of absorption, it is "OK" in the lows if it's thick, but it is always too powerful in the highs.
Last question, before hopefully making a clearer image of the possibilites:
The last thing I read was "limp mass" absorption. Seems to me like a simple and broadband bass absorption, is that right? Or is it much more complicated than it seems? Is it commonly used?
Thanks again everyone...
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Post by Deleted on Nov 25, 2020 12:29:57 GMT
Hi Hexspa, Thank you for your answer! I will probably agree with you in the future, but I always think one ends up simplifying things after one has studied a lot and worked with it. Trying a simple explanation requires discarding the complex ones...so that might have taken you time! I just didn't picture a simple solution for bass traping, as this was a problem I have never approached. I've read, and I never quite saw how they're constructed. So many things in the market, so different between them... I was proposing plastic over the wool as I assumed wool alone would have a bad balance of absorption, it is "OK" in the lows if it's thick, but it is always too powerful in the highs. Last question, before hopefully making a clearer image of the possibilites: The last thing I read was "limp mass" absorption. Seems to me like a simple and broadband bass absorption, is that right? Or is it much more complicated than it seems? Is it commonly used? Thanks again everyone... Actual good basstraps are hard to build. If you have even little lossy walls, you dont need the low bass trapping. (usually you do(lossy walls), unless you're in a bunker or concrete basement) If you want better room from untreated, just put up porous stuff and call it a day and go to work or enjoy music. There's just so many thing's that can and WILL go wrong, on your first attempts to the more complicated stuff. If you want a truly accurate room, hire a designer and do the build by yourself.
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Post by julian on Nov 25, 2020 15:01:37 GMT
Hi pasim! Thanks agains for your answers!
I think they don't have to be that hard to build...I mean, it has to be more or less straightforward.
I do think this is a job, and one has to hire people for doing them, but at the same time I think one may have the ability to learn how it is done.
(I know lossy walls helps. All the walls are lossy, I am taking this starting point.)
I just want to understand what makes a bass trap better than another...
My final thoughts are that bass traps are:
1)BROADBAND WITH A MID - HIGH FILTER, which is what I proposed before (although I need to know what is the plastic in question to cover the wool/fiber) 2)HANGING MEMBRANE, which is not at tension, floating non-hard heavy material, which an air chamber with wool behind. (what is called a limp mass)
Or maybe, the secret is a combination of both.
I feel I can't be so far from there. Otherwise, I will buy a professional trap, unmount it, and copy it (if I don't end up understanding why it works)
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Post by julian on Nov 25, 2020 15:02:48 GMT
and, I want to be able to do the best professional studio I can, otherwise I might not be worrying about bass traps
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