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Post by Quint on Jul 10, 2021 15:35:11 GMT -6
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Post by svart on Jul 12, 2021 11:46:37 GMT -6
Interesting. It still follows most of what the old papers you can find around the internet say. Density is king. Depth is queen. If something is not dense, make it deeper. If you can't make it deep, make it dense. |
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Post by bgrotto on Jul 12, 2021 13:32:52 GMT -6
Interesting. It still follows most of what the old papers you can find around the internet say. Density is king. Depth is queen. If something is not dense, make it deeper. If you can't make it deep, make it dense. I do appreciate how clearly the author illustrates the potential for *too* dense with regards to reflectivity of upper frequencies, though. That, and the correlation between a less-dense / more-deep trap to maximize efficiency. |
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Post by svart on Jul 12, 2021 13:44:45 GMT -6
Interesting. It still follows most of what the old papers you can find around the internet say. Density is king. Depth is queen. If something is not dense, make it deeper. If you can't make it deep, make it dense. I do appreciate how clearly the author illustrates the potential for *too* dense with regards to reflectivity of upper frequencies, though. That, and the correlation between a less-dense / more-deep trap to maximize efficiency. There's still some rule-of-thumb stuff out there about this, that depth with less dense material would be overall more beneficial than less depth but higher density, but it seems that there's been a lot of argument over whether high density really "reflects" more. Some data says yes, some says no. |
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Post by bgrotto on Jul 12, 2021 13:47:29 GMT -6
I do appreciate how clearly the author illustrates the potential for *too* dense with regards to reflectivity of upper frequencies, though. That, and the correlation between a less-dense / more-deep trap to maximize efficiency. There's still some rule-of-thumb stuff out there about this, that depth with less dense material would be overall more beneficial than less depth but higher density, but it seems that there's been a lot of argument over whether high density really "reflects" more. Some data says yes, some says no. Oh, interesting. So does that mean the model used by the calculator linked in that article is flawed? I'm curious to read more about that if you happen to have any links to papers at-hand. My poly diffusers build from a couple months ago got me real interested in this stuff...it's a helluva deep rabbit hole. LOL |
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Post by svart on Jul 12, 2021 14:26:25 GMT -6
There's still some rule-of-thumb stuff out there about this, that depth with less dense material would be overall more beneficial than less depth but higher density, but it seems that there's been a lot of argument over whether high density really "reflects" more. Some data says yes, some says no. Oh, interesting. So does that mean the model used by the calculator linked in that article is flawed? I'm curious to read more about that if you happen to have any links to papers at-hand. My poly diffusers build from a couple months ago got me real interested in this stuff...it's a helluva deep rabbit hole. LOL I'm sure there's something out there. Most of that stuff I picked up at Sayer's acoustics forum years and years ago when I was building out my studio. I read and learned enough to build the studio and promptly forgot a lot of stuff, but the rule of thumb I remember was that depth with less dense was better if you have the depth. I ended up deadening my ceiling by packing 3 layers of R30 (about 12" deep each layer) into about 15" of space and it worked great. |
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Post by Quint on Jul 12, 2021 14:31:48 GMT -6
From what I've seen, the low density of pink fluffy seems to be why it is routinely recommended for super chunk corner traps, due to depth you can use there. That's where I've used pink fluffy before.
As for the rest of the density versus depth stuff, I've never thought that hard about it before. I've just used OC703 or Rockwool for first reflection point/ceiling cloud kind of stuff and called it a day.
But after reading that article, I will probably take it more into consideration for any future treatment I build. I thought the author laid everything out in an easy to understand fashion. The graph and associated info for each depth/density scenario really presented things in a useful way.
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Post by Quint on Jul 12, 2021 14:33:03 GMT -6
There's still some rule-of-thumb stuff out there about this, that depth with less dense material would be overall more beneficial than less depth but higher density, but it seems that there's been a lot of argument over whether high density really "reflects" more. Some data says yes, some says no. Oh, interesting. So does that mean the model used by the calculator linked in that article is flawed? I'm curious to read more about that if you happen to have any links to papers at-hand. My poly diffusers build from a couple months ago got me real interested in this stuff...it's a helluva deep rabbit hole. LOL I've gotten interested in poly diffusers as well. I saw that you mentioned making some the other day. What'd you build them out of? |
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Post by bgrotto on Jul 12, 2021 15:31:43 GMT -6
Oh, interesting. So does that mean the model used by the calculator linked in that article is flawed? I'm curious to read more about that if you happen to have any links to papers at-hand. My poly diffusers build from a couple months ago got me real interested in this stuff...it's a helluva deep rabbit hole. LOL I've gotten interested in poly diffusers as well. I saw that you mentioned making some the other day. What'd you build them out of? Being the terrible carpenter that i am, i went as dumb/simple as possible: sheet of plywood with 2x2 sticks on either end, and a sheet of masonite bent into place between the sticks. Screwed that in place, capped the bottom with some plywood, and layered a buncha pink fluffy in (about 7" depth, held in place on the masonite with 3M spray-on adhesive). Kept the tops open so they don't become pressure traps. Pizza cake. |
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Post by Quint on Jul 12, 2021 15:52:39 GMT -6
I've gotten interested in poly diffusers as well. I saw that you mentioned making some the other day. What'd you build them out of? Being the terrible carpenter that i am, i went as dumb/simple as possible: sheet of plywood with 2x2 sticks on either end, and a sheet of masonite bent into place between the sticks. Screwed that in place, capped the bottom with some plywood, and layered a buncha pink fluffy in (about 7" depth, held in place on the masonite with 3M spray-on adhesive). Kept the tops open so they don't become pressure traps. Pizza cake. Did you do any kind of calculations on this? I'm guessing that, since the Masonite isn't porous, the pink fluffy isn't doing much besides damping the Masonite? |
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Post by bgrotto on Jul 12, 2021 16:02:36 GMT -6
Being the terrible carpenter that i am, i went as dumb/simple as possible: sheet of plywood with 2x2 sticks on either end, and a sheet of masonite bent into place between the sticks. Screwed that in place, capped the bottom with some plywood, and layered a buncha pink fluffy in (about 7" depth, held in place on the masonite with 3M spray-on adhesive). Kept the tops open so they don't become pressure traps. Pizza cake. Did you do any kind of calculations on this? I'm guessing that, since the Masonite isn't porous, the pink fluffy isn't doing much besides damping the Masonite? Ha, no, no calculations. Just lots and lots (and lots) of reading. The masonite is thin enough that stuff < 500c just sorta goes through it, and the pink fluffy does some trapping once the LF gets through. The polys basically diffuse above 500 or so, and the stuff below that gets absorbed. Did some measurements after mounting them, and they are effective down to 80hz (actually, even lower, but only sort of marginally) |
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Post by Quint on Jul 12, 2021 16:07:14 GMT -6
500c?
I need to read up on polys. My understanding of any kind of absorption is that it requires airflow to be able to pass through the pink fluffy, which the Masonite wouldn't allow. But I may be wrong on how this would work with polys.
Is there some sort of "this works in a lot of situations" poly design that you used? If so, got a link?
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Post by EmRR on Jul 12, 2021 16:52:34 GMT -6
I can add that a retired futon rolled up nicely to fill all the space under and behind the client couch, def does some lows control. : )
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Post by srb on Jul 12, 2021 22:12:34 GMT -6
I can add that a retired futon rolled up nicely to fill all the space under and behind the client couch, def does some lows control. : ) Haha. I still have more bass than I'd like at the couch on my rear CR wall, despite some effective trapping. I may have to get creative.  Like to clean that up a bit for client listening. |
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Post by bgrotto on Jul 12, 2021 22:12:37 GMT -6
500c? I need to read up on polys. My understanding of any kind of absorption is that it requires airflow to be able to pass through the pink fluffy, which the Masonite wouldn't allow. But I may be wrong on how this would work with polys. Is there some sort of "this works in a lot of situations" poly design that you used? If so, got a link? 500 cycles aka 500Hz. Sorry, i was being even lazier than usual  Airflow is achieved by leaving the top open. If the unit is sealed, it works as a resonator-type / pressure trap. At least, that's what I *think* the materials I was reading said. I'm no acoustician, so take anything i say with a big fat grain of salt. That is, other than the fact that these things worked exceptionally well - the audible difference was dramatic (you can hear for yourself if you track down my polys thread), and the measured difference confirmed it. The design I came up with was more or less pulled out of my a-- um, out of my imagination. I did a buncha window shopping on various forums, reading threads about builds, and read some tech-y documents (the Volkman one is sorta the bible, methinks, and easily found online), and the polys i made represent a sort of greatest-hits medley of the ideas contained therein. |
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Post by Ward on Jul 20, 2021 6:46:04 GMT -6
Interesting. It still follows most of what the old papers you can find around the internet say. Density is king. Depth is queen. If something is not dense, make it deeper. If you can't make it deep, make it dense. Deep thoughts for the dense. Ba=dum-pish. |
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Post by mrholmes on Jul 27, 2021 12:03:17 GMT -6
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Post by Bat Lanyard on Jul 27, 2021 21:36:15 GMT -6
I ended up deadening my ceiling by packing 3 layers of R30 (about 12" deep each layer) into about 15" of space and it worked great. Did a similar approach with my ceiling. Added Roxul between all joists above the ceiling sheetrock, added R30 above that and in the middle area where I raised it up I used 703 with a layer of R30 laid on top of it. Did add another layer of 5/8" sheetrock to the interior side of the ceiling across the whole room as well. |
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Post by svart on Jul 28, 2021 6:33:27 GMT -6
I ended up deadening my ceiling by packing 3 layers of R30 (about 12" deep each layer) into about 15" of space and it worked great. Did a similar approach with my ceiling. Added Roxul between all joists above the ceiling sheetrock, added R30 above that and in the middle area where I raised it up I used 703 with a layer of R30 laid on top of it. Did add another layer of 5/8" sheetrock to the interior side of the ceiling across the whole room as well. I left mine open and covered it with fire retardant burlap. The ceiling is now a huge absorber. |
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Post by Bat Lanyard on Jul 28, 2021 23:04:57 GMT -6
Did a similar approach with my ceiling. Added Roxul between all joists above the ceiling sheetrock, added R30 above that and in the middle area where I raised it up I used 703 with a layer of R30 laid on top of it. Did add another layer of 5/8" sheetrock to the interior side of the ceiling across the whole room as well. I left mine open and covered it with fire retardant burlap. The ceiling is now a huge absorber. Yeah, cool, whatever works. I added mass to stop transmission to the second story. |
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Like to clean that up a bit for client listening. 
