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1" vs 2" rigid fiberglass fabric covered wall treatmen
Old 5th April 2021
  #1
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🎧 15 years
1" vs 2" rigid fiberglass fabric covered wall treatmen

The title pretty much says it. I'm in the process of getting my iso booth done right. Currently, I have packing blankets and other makeshift things keeping reflections at bay. It's an odd triangular shape and already has a 8" deep, 6 foot by 4 foot bass trap.

Now its time to put 703 or rockwool with fabric to really contain the reflections and focus the room. 1" fiberboard is much cheaper and I wonder if it will be effective, or do I need 2".

Anyone use 1" for reflections and high-end control?
Old 5th April 2021
  #2
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Kyle P. Gushue's Avatar
 
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🎧 5 years
Something more like 4" of Rockboard 40 absorbs pretty much flat across the measured spectrum. 1 or 2 inches won't get enough LF and you will end up with a muddy room.
Old 6th April 2021
  #3
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🎧 5 years
I guesstimated thickness density etc and deeply regretted it. Find out the gas flow resistivity figure (rayls/m) for the material and use the calculator http://www.acousticmodelling.com/porous.php to see what effect different thicknesses have. There are always trade offs, but if you're more precise about it you'll use up much less space and end up with a better result.

You'll notice that there are some sweet spots for denser materials like 703 that allow for thinner panels and acceptable results. You'll also notice that lighter materials work better at greater thicknesses. It's a balancing act, that's why you need accurate figures.
Old 6th April 2021
  #4
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Quote:
Originally Posted by Kyle P. Gushue ➑️
Something more like 4" of Rockboard 40 absorbs pretty much flat across the measured spectrum. 1 or 2 inches won't get enough LF and you will end up with a muddy room.
There is a LARGE custom build [S.O.S style] bass trap already installed in the space. This is phase 2 of the rebuild.

Quote:
Originally Posted by replaceablehead ➑️
I guesstimated thickness density etc and deeply regretted it. Find out the gas flow resistivity figure (rayls/m) for the material and use the calculator http://www.acousticmodelling.com/porous.php to see what effect different thicknesses have. There are always trade offs, but if you're more precise about it you'll use up much less space and end up with a better result.

You'll notice that there are some sweet spots for denser materials like 703 that allow for thinner panels and acceptable results. You'll also notice that lighter materials work better at greater thicknesses. It's a balancing act, that's why you need accurate figures.
Thanks for this.
Old 6th April 2021 | Show parent
  #5
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🎧 5 years
Quote:
Originally Posted by Drumsound ➑️
There is a LARGE custom build [S.O.S style] bass trap already installed in the space. This is phase 2 of the rebuild.



Thanks for this.
A room that size needs bass trapping at all possible places. You need your broadband panels to be effecient at low frequencies. One bass trap isn't enough to handle all the LF.
Old 6th April 2021
  #6
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🎧 10 years
3" is minimum, 4" much better. Half of the room can be 2", but the half with 4" is much more important.

Better off treating less space with 4" then more space with 2"
Old 7th April 2021 | Show parent
  #7
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Quote:
Originally Posted by Kyle P. Gushue ➑️
A room that size needs bass trapping at all possible places. You need your broadband panels to be effecient at low frequencies. One bass trap isn't enough to handle all the LF.
The room size hasn't been mentioned. Its a small triangular booth.
Old 7th April 2021 | Show parent
  #8
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Kyle P. Gushue's Avatar
 
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🎧 5 years
Quote:
Originally Posted by Drumsound ➑️
The room size hasn't been mentioned. Its a small triangular booth.
You said its an iso booth in your first post. That means small area.

Do as you wish, you've been told what's correct.
Old 7th April 2021 | Show parent
  #9
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🎧 15 years
Quote:
Originally Posted by Kyle P. Gushue ➑️
You said its an iso booth in your first post. That means small area.

Do as you wish, you've been told what's correct.
Are you saying a smaller space needs more bass trapping?
Old 8th April 2021 | Show parent
  #10
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🎧 5 years
Quote:
Originally Posted by Drumsound ➑️
Are you saying a smaller space needs more bass trapping?
Yes, that is the general rule. Its a primary obstacle in studio design. The smaller the room the more bass trapping you need.

The reason the 4" rockboard is so useful, is that it absorbs evenly down to a usefully low frequency. It does work down at the low tones of a male vocalist, and a low E string on a guitar in standard tuning.

With 1" for example, its only effective down to say 500hz. So hypothetically let's say your bass trap is perfect from 20hz- 125hz (which no bass trap is in reality). If you line your booth with the 1", you now have a big, ugly peak from 125hz thru 500hz. Play a song thru your speakers, and boost from 125-500hz 12 or more db. It will not be good.

Notes on guitar in that range will poke out louder than others being controlled by trapping and the panels.

That's where a broadband panel that is even across the spectrum, plus focused bass trapping can help keep things smoother sounding without wonky resonances poking out.

If you use 2" stuff you can mount it with an airspace for improved low end, and you can do the same with 4" stuff.

Around North America 6" of rockwool safe n sound is the best bang for the buck. You can go thicker than that as well.
Old 4 weeks ago
  #11
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I agree. One large bass trap can never "suck" the bass out of the room. Quite the opposite, the bass will tend to go around it. Whereas if you cover the majority of the surface area with broadband that is effective down to bass frequencies this makes a bigger dent in the low end bumps.

Rockboard 40 is a good product. If you can go even thicker, Rockwool Safe N Sound is widely available in the US and works really well if you triple layer it, 9 inches thick total. 6 inches with a 3 inch gap is nearly as good if you need to save money, but of course in the end these both take up the same amount of space and it is better to "fill the gap" if you can afford to buy 50% more insulation. I have large 12 inch thick panels on my back wall, but on the doors (2 of them on the back wall) I could not risk mounting something so heavy as that, so I went 6 inch thick mounted 6 inches off the door. You can adjust depending on your needs. Air gaps can be used to increase the performance of thick traps or obtain "nearly equal" performance as a thick trap using less material.
Old 4 weeks ago
  #12
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🎧 15 years
I can't afford the space of 9 inches off of each wall. The Leslie lives in there and sometimes I'll have 2 amps with a divider. Basically taking each will in 9 inches would really kill too much space. I can add bass trapping above if it sounds completely out of whack after I do this step in the booth's evolution.

You guys have given me great things to think about. The bulk of the space goes up and peaks at 14 feel and there a 90ΒΊ corner that I can (and eventually will) do some sort of corner trapping. I might be able to do a Superchunk type deal ABOVE the area I'm working on next.
Old 4 weeks ago
  #13
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Gotcha. Yeah depending on how much space you can afford to give up, different products are appropriate. Something dense with high gas flow resistivity like Rockboard 40 is good if your panels are 4 inches. If you go a bit thicker, over 6 inches or so, then Rockwool Safe N Sound starts being a more optimal choice. Over around 10-12 inches thick, you would want to use fluffy attic insulation (just FYI, obviously you won't be going that thick).

Something to think about - I don't know about you but I don't typically use my ceiling for anything in particular... that is to say, the ceiling for me represents a lot of unused space that I don't mind occupying with thick absorbers. Another reason to go heavy absorption on the ceiling is because its parallel surface, the floor, is typically not going to have any treatment at all. Open-sided frames built with lightweight wood can make these lighter than you might expect.

The other option which may be a little more involved than you want to get, is to use tuned bass absorbers like a helmholtz resonator or a membrane absorber. I have also heard good things about "VPR" type traps though I don't know much about them. These are much easier to screw up than porous absorber panels, though. I've had both success and failure building tuned traps.
Old 4 weeks ago | Show parent
  #14
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🎧 15 years
Quote:
Originally Posted by Hot Sauce ➑️
Gotcha. Yeah depending on how much space you can afford to give up, different products are appropriate. Something dense with high gas flow resistivity like Rockboard 40 is good if your panels are 4 inches. If you go a bit thicker, over 6 inches or so, then Rockwool Safe N Sound starts being a more optimal choice. Over around 10-12 inches thick, you would want to use fluffy attic insulation (just FYI, obviously you won't be going that thick).

Something to think about - I don't know about you but I don't typically use my ceiling for anything in particular... that is to say, the ceiling for me represents a lot of unused space that I don't mind occupying with thick absorbers. Another reason to go heavy absorption on the ceiling is because its parallel surface, the floor, is typically not going to have any treatment at all. Open-sided frames built with lightweight wood can make these lighter than you might expect.

The other option which may be a little more involved than you want to get, is to use tuned bass absorbers like a helmholtz resonator or a membrane absorber. I have also heard good things about "VPR" type traps though I don't know much about them. These are much easier to screw up than porous absorber panels, though. I've had both success and failure building tuned traps.
The ceiling above actually is actually angled, which is good. I think I'll put some sort of corner bass trapping up in there, after this is done.

I also had a thought, based on a couple planing drawings from my contractor, musician builder friend (who will be doing most of the work on this) that I could possible put 1" rigid insulation with spacers of some sort that would put air behind the absorption, but I'm not sure it that is smart or not, especially if it is only an inch or less.
Old 4 weeks ago
  #15
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1 inch is not going to do much to any bass I would think. If you can increase the thickness, then maybe. But also you want to cover whole corners or surfaces if possible, since low frequencies tend to just bend around obstacles. And then of course, it's always better to "fill the gap" behind a panel rather than leave an air gap. So, whatever you can manage will be better than nothing, but 1 inch is only slightly better. If you can just fill the areas between studs with insulation and cover with fabric that is probably the easiest way to get reasonable absorption, though not having a layer of drywall would probably hurt the isolation.
Old 4 weeks ago | Show parent
  #16
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🎧 15 years
Quote:
Originally Posted by Hot Sauce ➑️
1 inch is not going to do much to any bass I would think. If you can increase the thickness, then maybe. But also you want to cover whole corners or surfaces if possible, since low frequencies tend to just bend around obstacles. And then of course, it's always better to "fill the gap" behind a panel rather than leave an air gap. So, whatever you can manage will be better than nothing, but 1 inch is only slightly better. If you can just fill the areas between studs with insulation and cover with fabric that is probably the easiest way to get reasonable absorption, though not having a layer of drywall would probably hurt the isolation.
The drywall has been there for years. There are studs, hushboard, and then drywall (maybe 2 layers, but I don't think the landlord actually did that). This is treating the interior walls of an already constructed studio booth.
Old 4 weeks ago | Show parent
  #17
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Quote:
Originally Posted by Drumsound ➑️
The drywall has been there for years. There are studs, hushboard, and then drywall (maybe 2 layers, but I don't think the landlord actually did that). This is treating the interior walls of an already constructed studio booth.
Okay I see. Well in that case, just go as thick as you can, use whatever product is appropriate for the thickness. For you, it seems like that will be Rockboard 40 as was suggested by Kyle. Pile it up on the ceiling if you can. Am I to understand that this room has no parallel surfaces? Triangular side walls with a vaulted ceiling?

A small room "sounds" small. Obviously the point of an iso booth is to have an area for recording away from other instruments and noises. It being small is by necessity but not because anything about a small room "sounds good." So whatever you can do to eliminate the sound of the room completely will be good.
Old 4 weeks ago | Show parent
  #18
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🎧 15 years
Quote:
Originally Posted by Hot Sauce ➑️
Okay I see. Well in that case, just go as thick as you can, use whatever product is appropriate for the thickness. For you, it seems like that will be Rockboard 40 as was suggested by Kyle. Pile it up on the ceiling if you can. Am I to understand that this room has no parallel surfaces? Triangular side walls with a vaulted ceiling?

A small room "sounds" small. Obviously the point of an iso booth is to have an area for recording away from other instruments and noises. It being small is by necessity but not because anything about a small room "sounds good." So whatever you can do to eliminate the sound of the room completely will be good.
Yeah, I'm pretty much eliminating the room sans for the air above.
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