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Post by adamforemusic on Jun 15, 2016 21:41:53 GMT
Hi Ethan, The room I have is rectangular, on the ground floor with nothing directly above me and only 1 wall is joined to the rest of the house (it was an extension built at the back of the house) Dimensions - L 6.5m W 2.8m H 2.4m ratio is 1.00 1.17 2.70 Floor - exposed (sealed and painted) concrete Walls - not completely solid except one which was an exterior wall. I'm planning to use it to record and mix in (I have an upright piano, drum kit, guitars and basses) I plan to do some soundproofing to the wall that joins the rest of the property to lessen the noise for others in the house. I am set up at the short end and can make my listening position 38% away from the front wall. I have a couple of questions in regards to the first half of your article 'Acoustic Treatment and Design for Recording Studios and Listening Rooms' 1. You say that the denser the fiberglass panel the more it absorbs at low frequencies, but you also warn that if a materials density is too high it will reflect more than it absorbs. Q. Is 100kg/m3 too dense to absorb frequencies between 60-300hz? Rockwool RW5 100mm has a density of 100kg/m3 I've been told by a supplier. 2. You say that for a given thickness of absorbent material, the ideal air gap is equal to that thickness, but you also advice to make the air gap as large as you can justify and that if you can afford to fill it, all the better. I appreciate the reason for making the air gap as large as you can justify, because to give an absorption panel the best chance of absorbing a 250hz soundwave you would have to place it 33cm away from the wall which is more space than the majority of people sacrifice. Q Should I fill the corner traps? I am thinking to either glue the 100mm rockwool RW5 slabs together to make 200mm slabs and leave an air gap behind, or is that a waste or fiberglass? Will 100mm RW5 slabs with an air gap behind be effective enough? If I fill the space behind, what density fiberglass would you recommend? I just watched your YouTube video on diffusion and I was shocked at how much more clairty there was when you played the guitar in front of the Real Traps QRD diffusor. I want the instruments to sound alive when recorded. Do you think placing two on the back wall and one on each side wall (toward the back - the 'live' part sounds like a good idea? If so I think I will buy 4 Q7D diffusors from GIK Acoustics (as they seem to be the only company that operate in Europe I can find). Do you have any experience with their diffusors and do you think that is a good place to buy them? See photos for an idea of the room.
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Post by Ethan Winer on Jun 16, 2016 17:29:19 GMT
1. No, 100 kg/m3 is fine. All I meant by "too dense" is when it starts to become as dense as wood. I'll also add that higher density helps mostly when the panels are relatively thin. For panels 2 to 4 inches thick (50-100 mm), higher density helps absorb more bass. But once the material is twice as thick or even thicker, less density works fine and also costs less. 2. Filling a corner increases absorption a little, but uses twice as much material. So if performance matters most, and cost matters little if at all, then fill the corner. Otherwise use 4 inch thick panels and have more of them around the room including wall-ceiling and even wall-floor corners. Another option is to fill the corner behind the denser panel with fluffy insulation, which costs less yet is better the nothing. I'll also mention that the ideal gap is related to the panel thickness. As above, for panels less than a few inches thick having a large gap creates "holes" in the absorption. Figure 5 from my Acoustics FAQ you referenced is repeat below for clarity. But once the panel is 4 inches thick or more you can benefit from a gap 3 or maybe even 4 times larger than the panel thickness. I say "maybe" because I know the principle is valid, but I never did controlled tests to derive specific thicknesses and distances. I can't help you much with GIK products, but I imagine their diffusers work as advertised. I'd be remiss if I didn't mention that RealTraps ships all over the world. But our products (and overseas shipping) are indeed more expensive. --Ethan
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My Room
Jun 17, 2016 6:13:53 GMT
via mobile
Post by adamforemusic on Jun 17, 2016 6:13:53 GMT
Thank you very much for taking the time to answer my questions Ethan. When I have done some more work to the room I will update the thread.
One more thing which I know you have talked about before. To get as close to the equivalent of 705-frk would you cover the 4 inch panels with black plastic garbage bags or Kraft paper? They seem like the two most affordable options for me.
I would love to give you my money and buy the real traps diffusors but I'm not sure I can justify the extra expense. I might PM you for a quote on 2 inc shipping just to get a rough idea.
Kind regards
Adam
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Post by Ethan Winer on Jun 17, 2016 18:23:53 GMT
I never compared paper to plastic directly, but I know for certain that both work.
--Ethan
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Post by adamforemusic on Jul 6, 2016 22:30:53 GMT
Hi Ethan, so I bought a 4 pack of RW3 (50kg/m3 density 100mm) to test out my absorption panel building skills (pictures attached) before my 48 slabs of RW5 Rockwool (100kg/m3) arrives on Tuesday. I am planning on building a stud wall along the length of the room that joins the rest of the property to isolate more of the sound from the live instruments. The wall is the previous exterior wall (as the room I'm in was built as an extension), there are two doors on that wall, one set of double doors, which is where I particularly want to isolate the sound from, are solid oak, and will not be in use (I have tightly packed in the alcove from the adjoining room with 100 yrs worth of national geographic magazines, so there is a decent amount of mass there). The other single door will be my main entrance to the room, it's got 1 ft of hollow sounding wall around it before it becomes the solid exterior wall but I don't intend to mess with the walls to fill them in with timber - I removed a small rectangle of the drywall which revealed a piece of timber (see picture) but thats as far as I went. I have some questions regarding this and other points. 1. Should I leave an air gap between the wall and the stud wall I build, if so, how big would you suggest? (the room is only 285cm wide as it is) 2. How should I arrange the order of materials when constructing the stud wall, drywall - rockwool - drywall, for example? 3. The 1 ft of hollow gap around my entrance is (I assume) going to undermine all of the hard work I do to isolate the sound from the rest of the property, and it will make my intentions of having a solid core door with good seals pointless. How would you suggest I go about this issue? Could I make a beefy 1 ft wide border around the door frame out of 2x4s? Will that have any effect? Thanks for your help, any suggestions from anyone on your forum are most welcome! Adam
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Post by adamforemusic on Jul 6, 2016 22:31:55 GMT
Here is a picture of the entrance to the room. Attachments:
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Post by Ethan Winer on Jul 7, 2016 19:19:37 GMT
1. Yes, an air gap extends absorption to lower frequencies. Make it as large as possible, up to twice the panel thickness. 2. Walls usually have fluffy insulation between the drywall. There's no need to pay more for high density insulation there. 3. Without actually being there to see it in person it's tough to suggest what you should do. That's not really my area of expertise anyway. But generally, Yes, you want to beef it up with solid stuff like wood and make sure there are no air gaps. You can also buy professional door seals, though they're not cheap. This place has many such products: www.zerointernational.com/index.aspx#--Ethan
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Post by adamforemusic on Jul 7, 2016 22:11:22 GMT
I ripped off the bit of dry wall on one side of the door (see picture) , i assume its the same the whole way around which i will uncover tomorrow, this is good news as I can now fill the gaps properly. Whats the best thing to do here? wood or insulation? I'm wondering if John H. Brandt would also be willing to give some input here? Any helpful suggestions or tips would be great. Also I'm now undecided on whether to build a stud wall or just essentially a box in front of the oak doors to stop as much sound as possible going through there, if I do the whole wall I won't have access to the radiator which isn't great.
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Post by Ethan Winer on Jul 8, 2016 18:44:23 GMT
I hope John chimes in too because he knows more about this than I do. Generally, you want solid walls with mass, and fluffy insulation inside. I can also tell you that the principle of "weakest link" applies. Even if you had a door and frame that stopped sound completely, the walls and floor etc all touch each other and transfer sound via "flanking paths."
--Ethan
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Post by adamforemusic on Jul 8, 2016 23:16:31 GMT
Thanks Ethan, just to clarify my plan.
For the Oak Doors I am going to build a partition wall 11 or so inches away from the doors using 2x4s, I am going to cover it with 3 layers of fire rated drywall, staggered across the studs so that the joins aren't in the same place, I'm going to fill the area behind with cheap insulation then seal it with backer rod and sealant so its air tight.
John could you please suggest what to do for the door in the picture shown 2 posts above. its like that the whole way around the door way.
Kind regards
Adam
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Post by rock on Jul 8, 2016 23:37:01 GMT
Adjacent ceiling, walls and floor are also involved in conducting vibrations into and through the wall/door in question. When addressing the issue of acoustic isolation, a holistic approach needs to be considered. Ethan mentioned "flanking paths" and that's the big problem... With "beefing up" the obvious or primary weak link only to find all the other "weak links" that will emerge. I also hope John chimes in since isolation is a completely separate issue from acoustic treatment. I like to recommend Rod Gervais' book on studio building like the pros.
When the band comes over to practice at my house, the entire house is filled with noise (yeah, we play too loud) and there is nowhere for my wife to escape... so she puts up with it (she's a saint!). To solve the isolation problem, I know I'd have to tear all the walls an ceiling bare and start from the studs/joists. Not gonna do it.
Cheers, Rock
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Post by rock on Jul 8, 2016 23:47:55 GMT
Hi Adam, we must have been typing at the same time. Sounds like you're building a double wall. Good idea. Read Rod's book. There's this concept of M-A-M. A good wall will have 3 and only 3 components. Mass, Air (or fluffy insulation) and Mass. Your mass layers can be as thick as needed like 3 or 4 layers of drywall but just one composite on each side of the Air or insulation in the middle. Use mineral wool compressed under (and over) the partition's floor and ceiling plates.
Cheers, Rock
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My Room
Jul 9, 2016 8:02:39 GMT
via mobile
Post by adamforemusic on Jul 9, 2016 8:02:39 GMT
Hi Rock, thanks for your reply.
I should probably take the time to read a couple of acoustics / studio design books to really understand all the elements of the problem but I'm a musician not an engineer and I have some time constraints. I do find in all very interesting though and will endeavour to have a read of Rod, Ethan and John's books. Saying that, I do of course want to get it as 'right' as I can, the first time. I have financial constraints and I know my limitations for the project.
I appreciate low frequency loss is basically unstoppable in my situation, but I want to do my best around the weaker spots of the room as the rest of the connecting wall is concrete, and my neighbours aren't an issue. I just want to know how I can get that hollow bit near the door frame so it's as close to as massive as the concrete wall that stands next to it.
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Post by rock on Jul 10, 2016 15:47:06 GMT
Hi Adam, I have to admit, but I am unable to completely understand the exact construction of your building and room but if I am to understand that the building is a solid concrete box or at least there are no other tranmission concerns or with flanking etc. except for the framing you have exposed, and all you need to do is to bring that section of the wall up to the same STC of the concrete wall, first determine the STC of the concrete wall. www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=stc+rating+for+poured+concrete+walls www.ncma-br.org/pdfs/5/TEK%2013-01C.pdfThen build your partition using drywall and framing to the same STC. This can be two separated wall sections, each with layers of drywall on only the outsides and the space filled with fluffy insulation. The number of layers and thickness for your STC can be found from building and material pdfs like above. Finally, use a solid core exterior door or one with a stated STC, you might need to use a double door, one on each wall. In the case of the double door, one usually stand open the majority of the time except for when the most transmission isolation is needed. Of course you'll need to use appropriate door sealing techniques. I am not a professional builder but I've done several projects so even though I have ideas and opinions, they are just that. Sorry to say you should not proceed on my suggestions alone but this is one way to approach the project. Lots of us want to DIY this stuff but I think it can be pretty tricky to get the best results without professional advice or help. Cheers, Rock
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