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Post by paindpt on Aug 19, 2016 7:52:56 GMT
Hello, Ethan. I would like to ask you some questions on acoustic treatment in the home studio based in the attic of a house, if I may. The complication is that the ceiling is angled. I've read some of your articles where you stated that this is not a problem at all, and that this kind of celeing should almost be treated like a normal one. But every room is special, so I've got to be sure. I attach the photos of the attic for you to evaluate the situation. The room is rather large and there's, actually, an option to build a wall across these iron pillars if necessary (explained in one of the pictures). The location of the sound engineer is also seen on the picture. The main concern is unevennes of the stereo sound picture because of the angled ceiling on the left side of the mixing desk. So, the questions are: 1) Should we build the wall across the iron pillars? (to make the stereo field more even) 2) Should the angled ceiling be treated somewhat special in my case? How, for example, bass traps shold be placed? 3) Shall we make special acoustic treatment in the walls during construction? I mean purposfully like as we're building the studio using special materials or will just the foam and bass traps on the unprepared walls be enough? I'm planning to do just the mixing\mastering work there and maybe some vocals recording. Nothing special. Thank you very much! |
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Post by rock on Aug 19, 2016 12:44:18 GMT
Interesting space. The symmetry is across the width which seems to be fairly narrow so that's not recommended but your other choice, firing your speakers down the length is not great either since the left/right symmetry is way off.
A diagram with dimensions would be helpful. Are you going to finish the walls with drywall or wood panelling or just leave them as they are?
If this is the only space you have and want to make the best of it, generally, you put bass traps in all the corners and treat for first reflections and flutter echoes. In your "proposed wall" you could create a giant bass trap with a fabric covered "false wall" with fluffy insulation filled in the space behind. With this, the four adjacent corners of the "false wall" will be addressed. I wonder what Ethan's suggestion would be but to have symmetry, you'd have to fire your speakers across the width. This is not great but if you trapped the "proposed wall" as I mentioned, that would eliminate reflections from the rear. You could also put absorbers on the ceiling behind you.
1. I don't think you can do anything with that wall to get an "even field". The best you can do is make it a giant bass trap but that does not even out anything.
2. Ceilings are treated firstly for reflections, secondly for taming flutter echoes and reducing RT60, and thirdly for additional bass trapping. So because your ceiling is at an angle, you still treat it for those reasons. Bass traps go across the corners.
3. Yes, you can build absorbers into your wall instead of attaching them to the wall. It's more of a construction choice than what will be better acoustically. For instance, a 2'x4' 4" thick absorber will do the same thing if it's "built in" or "hung on" the wall. If you decide to cover a wall, you can stud the wall and fill with insulation then cover over the studs with fabric. That can be easier than building panels but you loose the flexibility.
Since you have a non-rectangular room, your room modes will not be (easily) calculated. Optionally, you might acoustically measure your empty room to see what you dealing with and what frequencies your modes are. This may be help as you apply treatment but it's just optional and in general, the more bass trapping is better and the smaller the room, the more absorption of mid/high as well.
Cheers,
Rock
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Post by rock on Aug 19, 2016 19:35:52 GMT
Something I missed is that your ceiling is apparently insulated with paper faced insulation of some kind. This is good, exposed the way it is, as you probably have some degree of low frequency absorption there. To enhance/improve the mid/high freq absorption, use un-faced absorbers BUT, I'll suspect you'll get more mileage with the giant bass trap and corner traps and then addressing the brick walls with wide band absorbers. (Thicker is always better. Air space equal to absorber thickness increases LF performance for FREE except you give up some space.)
Many decisions usually include expectations, budget, time etc. so what you do will be determined by those and other forces unknown to me.
Cheers,
Rock
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Post by Hexspa on Aug 22, 2016 14:42:54 GMT
My opinion is face the pillars, don't build a wall inside that wedge, instead fill it with fluffy.
Be sure to treat your rear wall with very thick fluffy, maybe 24" worth, as well as the sides and ceiling.
Like Ethan says, there's no difference between no walls and heavily absorptive ones so, considering that room is wild, tame it with extensive insulation.
Also, if you keep your speakers near your head you'll maximize direct signal. Of course you won't get a wide soundstage but it'll be ok.
-m
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Post by paindpt on Aug 23, 2016 11:38:04 GMT
Thanks for the feedback, guys! The material to finish the walls is another topic to discuss as I'm also concerned about it. I thought about fabric as a finish, and combination of layers of very thick fluffy and foam rubber according to Phillip Newell. What do you think about it? Actually my main concern with acoustics there is the low freqs. I thought about building the sand-filled floor and using the thickest fluffy I can get to tame the lows. The bass traps confuse me as I don't know what kind of them to use: the smaller foam ones or the larger panel ones? The positioning is also a mystery. What to consider a corner on an angled side of the ceiling? I just can't visualize that. I also wonder what material should the "possible' wall be made of if built. I don't want to face the pillars as I really feel I should be seated to shoot the speakers across the length of the room. And because of that it's also interesting where to put the foam absorbers. There's a standard scheme for rectangular rooms (attached), which I have trouble adopting to my setup. Attachments:
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Post by Ethan Winer on Aug 23, 2016 22:01:19 GMT
Usually it's better for a room to get wider or higher in the rear. But in your case I'd face the main vertical wall, and stuff the entire cavity behind the iron with fluffy insulation all the way back to the corner. As Rock said, you'll need something that absorbs better for mids and highs on the angled wall. But it doesn't have to be thick. Even 1-inch thick rigid fiberglass, or 2-inch thick foam, behind your head will be fine.
--Ethan
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Post by Hexspa on Aug 24, 2016 0:06:48 GMT
Usually it's better for a room to get wider or higher in the rear. But in your case I'd face the main vertical wall, and stuff the entire cavity behind the iron with fluffy insulation all the way back to the corner. As Rock said, you'll need something that absorbs better for mids and highs on the angled wall. But it doesn't have to be thick. Even 1-inch thick rigid fiberglass, or 2-inch thick foam, behind your head will be fine. --Ethan Respectfully why, Ethan? I can understand why he wouldn't want to fire down the length because of the angle but why face the vertical wall; because it acts like a corner? I'm genuinely curious. And to paindpt - I think positioning can be simplified by the metaphor of disappearing walls: if your walls aren't there, they can't cause problems. Thus, if you treat them maximally they are a non-issue (at least practically). All the corner, superchunk, "cloud absorbers" and RFZ specifications are dual-purpose: to make most effective use of materials and to educate on critical points and WHY you treat at all. But look at an anechoic chamber - they don't have rigid panels diagonally across the corners nor do they have "rfz" panels. Why? Because there's no need - everything is maximally absorptive. I hope that makes sense. I specified this in a video I've yet to make public but this post summarizes it well. At least this is my understanding. I hope I'm right because the video is going up regardless lol. Thanks, -m |
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Post by rock on Aug 24, 2016 1:36:37 GMT
Hi paindpt,
Here are some comments regarding your last post:
Yeah, some kind of open weave fabric, burlap is one but there are other choices. I don't know about the layering of foam and fluffy but fluffy is way cheaper than acoustical foam products but the foam is decorative and does not need to be covered.
The sand filled floor would add mass which would help reduce transmission but that's another subject. Do you need acoustic isolation from the rest of the building? If so, that's a completely different matter and acoustic treatments will do little to nothing to help. I think, instead of sand, reinforced concrete will have structural value where sand will just be a load. Either way, you'll need to consult a structural engineer but hopefully, you won't have to go down that road.
Bass traps: 1. the thicker, the lower the frequency 2. the more area coverage, the more of that frequency they absorb. So you need both thickness 4" to 6" inches and coverage 2' x 4' panels of rigid fiberglass or mineral wool are good, solid superchunk are better if the coverage is equal to the panels because of more volume of insulation. Corners are simply where two (or three) surfaces meet. The bass traps straddle the corners. In YOUR room many corners are not 90 deg. (some are greater than 90 and some are less) but they are STILL CORNERS so just straddle them. (sorry for shouting:)
About the corner in your room that is greater than 90 deg is the corner where the ceiling meets your "possible wall" in the back. If you fill the space behind the pillars with fluffy and stretch and staple fabric across the "possible wall" you now have a giant superchunk and it will effectively trap all the adjacent corners to itself including where it meets the the ceiling. Bottom line: you don't need bass trap panels across those adjacent corners as they are already treated.
Possible wall fabric: Open weave as mentioned above. You'll probably need to install more vertical studs for stapling fabric to.
Of course you don't have a rectangular room. I think our suggestions are to try to make the best of the room you actually have.
Cheers,
Rock
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Post by Ethan Winer on Aug 24, 2016 17:01:48 GMT
He needs to face either the main wall or the "crawl space" for symmetry, and facing the main wall puts half (on average) of the surface behind him farther away. If he faces the low part, there's a wall literally two feet behind his head. --Ethan |
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Post by Hexspa on Aug 25, 2016 17:55:40 GMT
He needs to face either the main wall or the "crawl space" for symmetry, and facing the main wall puts half (on average) of the surface behind him farther away. If he faces the low part, there's a wall literally two feet behind his head. --Ethan Ok. And from what I understand the rear wall is a critical point so, despite the amount of treatment, it's better to be further away. Thanks, -m |
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Post by paindpt on Sept 2, 2016 11:13:01 GMT
Thanks again, guys! I understood everything Rock said, the angles explanation is hyperinformative  Also Hexpa was talking about the initial building stage room preparation. Yeah, that's exactly what I was into from the very beginning, we'll try to do maximum on that initial level and then, if anything is still there, we'll use traps and stuff. That was one of my questions, thanks! There's one thing I can't understand. Ethan, can you, please, explain what wall do you consider "the main vertical" one? Because there're 2 vertical walls there. I've read your and hexpa's messages several times, but still couldn't figure that out. |
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Post by rock on Sept 2, 2016 13:00:51 GMT
From what I gather, I'm pretty sure that by the "main vertical wall" Ethan means the wall that is opposite or across the width of the room from what we are calling the "possible wall".
Cheers,
Rock
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Post by Hexspa on Sept 3, 2016 8:33:50 GMT
The main vertical wall is the wide one with the 90 degree angle.
I think.
Basically in your room you'll eschew the typical approach of "firing down the length" and instead fire down the short side - that angled wall will be behind you.
I think.
Adding to my current understanding: your front wall is relatively meaningless. In contrast, your rear wall is significant - especially when very close. Therefore, if you face the wide front wall, you'll have more length behind you. That space can become absorptive and is at least not a flat surface, per Ethan, behind your head. It's like a mirror - no one is glamorous up close and flush; a little angle might do you good. In that sense, having that angled cavity behind you will reflect the sound down and not "right back at'cha." Additionally, since symmetry ahead of the listening position is critical, you can't "fire down the length" because that angle is going to irretrievably f your imaging.
Dang I can't wait to see some REQ on this.
-m
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Post by rock on Sept 3, 2016 15:11:28 GMT
Hi paindtp,
I was looking at your photos again and thinking dimensions might give me a better idea of what's going on over there. When measuring length, please go from wall to wall. Width, measure from the "front" wall to the pillars. For the height, measure the height of the "front" wall and also the height at the pillars.
Also from the photos, I realize you'll probably want to build up the floor since those channels on the floor appear to have a structural purpose and if you don't, you'll end up tripping over them. As a byproduct of building up the floor, you'll have an opportunity to create "chases" to hide cable runs. With some forethought about your possible uses, it could work out quite nicely. You can install electric power outlets in the floor too. Of course, you want to keep power away from audio signal but that's just another part of studio design.
Cheers,
Rock
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Post by Ethan Winer on Sept 3, 2016 20:23:36 GMT
I'm pretty sure that by the "main vertical wall" Ethan means the wall that is opposite or across the width of the room from what we are calling the "possible wall". Yes, exactly. To me, the brick walls I see in the photo are the side walls, and not suitable for the front or rear. --Ethan |
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