tomas
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Post by tomas on Apr 28, 2016 12:23:26 GMT
Hello there! I am going to create my mixing/tracking room very soon and would like to discus few things. I've created this sketch by now:
Room dimensions are: 3950x4900x2010mm (yep pretty low ceiling ) Please check the numbers in the images. Here's what they are: A - Early reflections absorber. Is it ok to use 2'' mineral wool 2'' from the wall? This wool I picked has pretty good gas flow resistivity (21 or 27 kPa*s/m2, depends on the type I'll chose). Those two on the left are in front of the windows. I'll try to make them removable just to be able to open the window some time. B - Corner bass traps. Is it ok to use mineral wool with gas flow resistivity of 5kPa*s/m2? The triangle dimensions are 31x31x45cm and will be full of the mineral wool. C - Trying to remove the ceiling from the equation by these absorbers. Probably will use same material as on early reflections absorbers (letter A). Is that ok? There will be also 2'' air gap from the ceiling. D - wooden (is OSB good for this?) platform for drums. 1cm thick to not to make the ceiling even lower. E - basic carpet just to loose some reflections from the floor under the listening position. As you can see there is also a sofa in the room (can't move to any other room, must stay there. Is there a better place for it? There is door on the wall from which we are looking into the room so can't be placed there). Isn't it a problem to have one inside? The vertical thing behind the sofa is chimney. Can't get rid of this one too. So am I on a good way to create some decent sounding room or not?
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Post by Ethan Winer on Apr 28, 2016 17:26:25 GMT
A - Yes, perfect.
B - almost any mineral wool is fine, especially if you're filling the corners. But 45 cm is not wide enough. Can you make the corner traps twice as wide? If not, just make them as wide as you can.
C - Sure, though even thicker can only help.
D - I don't know of many reasons to build a platform for the drums. Are you trying to isolate impact sounds going down through the floor?
F - Carpet helps, but get the thickest type you can afford, and also add a thick pad underneath.
--Ethan
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tomas
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Post by tomas on Apr 28, 2016 23:49:36 GMT
A - Yes, perfect. B - almost any mineral wool is fine, especially if you're filling the corners. But 45 cm is not wide enough. Can you make the corner traps twice as wide? If not, just make them as wide as you can. C - Sure, though even thicker can only help. D - I don't know of many reasons to build a platform for the drums. Are you trying to isolate impact sounds going down through the floor? F - Carpet helps, but get the thickest type you can afford, and also add a thick pad underneath. --Ethan B - isn't it better to use the same material as in the 'A' absorbers and leave some air gap in the corner behind the trap? You know what I mean? C - "even thicker can only help" - means that this one I picked is cool but the thicker the better? D - Well lot of people use a platform for drums to get the right resonance. I have no experience with it I want to try it definitely. Do you have any experience with drum platforms? E - what kind of pad are you talking about? Anyway what about some diffusers? I suppose I should put some on the wall that's not shown on pictures. What kind? How big? Any other place? Front wall? Thanks!
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Post by Hexspa on Apr 29, 2016 0:44:39 GMT
B - If you use a dense (more gas flow resistivity) material and using a thickness less than 20cm then adding an equidistant air gap behind is helpful but stuffing it will probably help too. If you're using a less dense material (R 13-19) then make them very thick, fluffy and filled-in. Ethan's referring the the "face" of the trap where sheer coverage in m2 is relevant - the physical size matters in addition to the material's properties.
C - Use the material on-hand but just double/triple it up to 10-15cm.
E - Probably just regular carpet padding. I think he means adding a thick carpet pad underneath just to act as a type of high-density absorber.
Typically you want your floor reflective and your ceiling absorptive but in your case, with a 6.5' ceiling, idk whether it matters.
Diffusers - Rear wall gets well QRD diffusers as large as possible. Adding them anywhere else in the room, besides the ceiling and corners, can only help so long as it's not at first reflection points.
From what I've seen, and if I was you, I'd spend less effort on the ceiling, floor and diffusion and more on the corners, first reflection points and absorption. 3 point corner absorption, creating a reflection-free zone and correctly positioning and orienting your listening position seem to give best bang for the buck - keep it simple and cheap.
My dos pesos,
-m
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tomas
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Post by tomas on Apr 29, 2016 6:40:53 GMT
C - Use the material on-hand but just double/triple it up to 10-15cm. Well that's a little bit an issue with my ceiling. I am really worried about it but I want to do my best to get at least usable sound from recordings. Thanks for the advices man! Oh an as fas as diffusers. How can I determine which frequency do I need to diffuse?
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tomas
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Post by tomas on Apr 29, 2016 13:55:41 GMT
B - If you use a dense (more gas flow resistivity) material and using a thickness less than 20cm then adding an equidistant air gap behind is helpful but stuffing it will probably help too. If you're using a less dense material (R 13-19) then make them very thick, fluffy and filled-in. Ethan's referring the the "face" of the trap where sheer coverage in m2 is relevant - the physical size matters in addition to the material's properties. Oh and as far as a 'B' trap. I want to save as much space as possible. So which way is the way to go? Dense material with an air gap or stuffing fluffy one into the corner?
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Post by Ethan Winer on Apr 29, 2016 17:20:42 GMT
You mentioned triangles for the trap in "B," so to me that implies a corner filled solid rather than a panel with an air gap.
--Ethan
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tomas
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Post by tomas on Apr 29, 2016 18:18:45 GMT
You mentioned triangles for the trap in "B," so to me that implies a corner filled solid rather than a panel with an air gap. --Ethan So it's better to go with fluffy triangles then with dense panel + air gap in the "B" trap right? And an opposite in the early reflection panels. Am I right? I am also able to buy pretty dense panel (84 kPa.s/m2). What might be the best one for an "A" traps? These are the possibilities: 84 kPa.s/m2, 27 kPa.s/m2, 21 kPa.s/m2, 16 kPa.s/m2, 14 kPa.s/m2. So which one would be the best?
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Post by Hexspa on May 1, 2016 6:22:34 GMT
If I were you, or anyone else that's in a conventional domestically-sized locale, I'd conform to a single standard of 4" thick OC 705, or equivalent, across corners and at early reflection points with an air-gap behind.
All else is vanity.
-m
PS - In the spirit of being helpful, if less concise and poetic, remember that early reflection points will change whether you're in the big-boy seat (mixing sweet spot) or for instruments in the condition of live recording.
Just stick to one treatment method to start off with. Then listen, measure and solicit feedback. The gold standard is OC 705 (at least afaik - hey it even happens to be yellow). Start there. You gotta fix your bass so treat your corners. You want clearer imaging and high frequency perception so treat your early reflection points. Four inches thick is pretty much good for most situations. If you got money then make 'em six inches thick. If you got more money do superchunk (filled corners). Just don't go deeper than eight inches for dense material. In that case switch over to less-dense (fluffy).
But really strive to keep it simple.
Tomas, you've helped remind me how lost I was regarding this topic when first starting out - and I'm still lost! That being said I'm confident that I know enough, and have practiced enough, to help just about anyone improve their small room acoustic situation - but mainly thanks to Ethan's fine and priceless resources and my scrupulous scouring thereof. Please read everything on his Real Traps site at least thrice!
Again, keep it simple and good luck.
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tomas
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Post by tomas on May 1, 2016 8:41:16 GMT
If I were you, or anyone else that's in a conventional domestically-sized locale, I'd conform to a single standard of 4" thick OC 705, or equivalent, across corners and at early reflection points with an air-gap behind. All else is vanity. -m PS - In the spirit of being helpful, if less concise and poetic, remember that early reflection points will change whether you're in the big-boy seat (mixing sweet spot) or for instruments in the condition of live recording. Just stick to one treatment method to start off with. Then listen, measure and solicit feedback. The gold standard is OC 705 (at least afaik - hey it even happens to be yellow). Start there. You gotta fix your bass so treat your corners. You want clearer imaging and high frequency perception so treat your early reflection points. Four inches thick is pretty much good for most situations. If you got money then make 'em six inches thick. If you got more money do superchunk (filled corners). Just don't go deeper than eight inches for dense material. In that case switch over to less-dense (fluffy). But really strive to keep it simple. Tomas, you've helped remind me how lost I was regarding this topic when first starting out - and I'm still lost! That being said I'm confident that I know enough, and have practiced enough, to help just about anyone improve their small room acoustic situation - but mainly thanks to Ethan's fine and priceless resources and my scrupulous scouring thereof. Please read everything on his Real Traps site at least thrice! Again, keep it simple and good luck. Ok so first of all I can't get OC 705 as I am located in Slovakia and it's pretty much impossible to get these. BUT! As far as I know, the air flow resistance (AFr) of OC 705 is somewhere around 30kPa*s/m2 (am I right?). An equivalent I found here in local store is Isover ORSTECH 65 with AFr around 27kPa*s/m2. So I've decided to go with this guy for most of my room treatments. Second of all. I've found this great absorber calculator and I don't know what am I doing wrong, but it looks like 20 cm thick fluffy mineral wool with AFr of 5kPa*s/m2 behaves a lot better then 10cm dense absorber with AFr of 27kPa*s/m2 with 10cm air gap in whole frequency range. So why getting expensive dense material? Anyway I am pretty sure I'm just missing something and it's not like I solved the biggest acoustic question lol. So what is it? Why my graph looks like this? Oh and I've started to study some diffusers lately and I've decided to go with 1D QRD diffuser on my back and front wall. I'll go with DIY model made of extruded polystyren. I'll buy some amount of 4cm thick XPS boards (1250x600mm) and will cut them to make each well the proper depth. So I'll get pieces of DEPTHx600mm which I'll glue together to get this N23 diffuser: The frequency is based on what I've already read from Ethan's work and comments. (Gearslutz 11.05.2009: "If you design the diffusor to work from maybe 800 Hz to 3 or 4 KHz, that should be fine. Going much lower requires a lot of diffusor depth, and diffusing bass frequencies may not be so useful anyway." - Ethan Winer.) So I'll end up having 960x600mm diffuser for back wall and will do one more for front wall. Will that be ok? Did I missed something? PS.: I am worried how to mount that diffuser on the wall so it won't shake when the bass kicks in. Any suggestions?
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Post by Rock on May 1, 2016 16:14:25 GMT
I've been following this thread and I just want to share my perspective on bass traps. I think you guys probably know all this (well of course Ethan does!... that is if what I have here is correct) but I'm a little confused by the discussion so maybe it's just me. 1. THICKNESS and DENSITY. The depth or thickness determines the low frequency effectiveness, the thicker, the lower. Greater density is more effective at lesser thickness (<~4") but becomes more equivalent to lower densities (fluffy) at greater thickness (>~8"). 1a. AIR SPACE. An air space effectively lowers the low frequency by making the absorber "virtually thicker" with respect to it's distance from the wall. Filling the air space with more absorption will improve the effectiveness but with diminishing returns with respect to cost of materials. If cost is not an obstacle, fill the space... but not at the expense of less coverage (see "2" below). Also note, the low frequency effectiveness of any thickness absorber gradually rolls off and it does not abruptly cut off at some given frequency. If I can quote (or at least paraphrase) Ethan correctly "Even a washcloth will absorb some low frequency... just not very much " 2. AREA OF COVERAGE. The area of coverage with respect to the room surfaces, determines the overall effectiveness of your traps. If your trap area coverage is too small, it will make little difference regardless of how thick or what density they are. Conclusion: The thickness and density are important but without enough area coverage, you'll be better off with less thickness (but at least 4" dense) and more area coverage. Tomas, did you try to find mineral wool or rock wool (Thermafiber)? The kind I can find in the Chicago area is similar in density to rigid fiberglass. As far as I know this is essentially correct but if not, please set me straight. Thanks, Rock
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tomas
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Post by tomas on May 1, 2016 17:30:12 GMT
Tomas, did you try to find mineral wool or rock wool (Thermafiber)? The kind I can find in the Chicago area is similar in density to rigid fiberglass. The material I am talking about is ISOVER ORSTECH 65 and it's stone wool. Is that a problem?
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Post by Rock on May 1, 2016 18:42:00 GMT
Great, seems that mineral, rock and stone are all pretty much the same thing when it comes to wool so yes, I imagine that should work fine!
Cheers, Rock
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tomas
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Post by tomas on May 10, 2016 19:34:07 GMT
Now I am thinking. Isn't it better to place a dense material (+-30kPa*s/m2) into corners where the low frequencies are cumulated, and less dense and more fluffy material (+-5kPa*s/m2) as first reflection panel to absorb frequencies that can be reflected otherwise (300Hz+) ?
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Post by Hexspa on May 11, 2016 6:03:01 GMT
Now I am thinking. Isn't it better to place a dense material (+-30kPa*s/m2) into corners where the low frequencies are cumulated, and less dense and more fluffy material (+-5kPa*s/m2) as first reflection panel to absorb frequencies that can be reflected otherwise (300Hz+) ? I think it comes down to thickness and something about dense material not working as well at greater than 8" - that's where less-dense starts to shine.
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