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Post by emmett13 on Dec 16, 2020 17:35:05 GMT
Hi everyone,
It's my first post here, though I've read through a lot of posts and Ethan's resources over the years, and have built a good number of DIY broadband absorbers and bass traps for a prior small mixing room.
I bought some Knauf Ecobatt 12" R38 batts to shove up in my basement's drop ceiling between the joists (at least in the corners), however the Home Depot only had the Kraft faced version. I wanted to know if I should install facing-side-out as one would if using as standard insulation, or if this will somehow affect absorption. I can also look for unfaced insulation if that's better (or less expensive). I'm open to suggestions and can easily take the Ecobatt back—i just like that it's more eco-friendly, etc. I paid about $70 for a pack of 11 batts. This is a rental property, and I may not bring the insulation with me when I leave, so I don't want to spend a ton of money.
Also, I'm in a fairly big semi-finished basement with a diagonal wall (single layer of drywall) in the middle of the room boxing out the furnace, and a lot of stored items on palettes and shelves (natural diffusion?) on the far walls. Without going too crazy, would a couple of 703/rockwool or comparable broadband absorbers on the available wall faces/reflection points be a good idea to dampen higher frequencies? I could probably keep or sell these when I move.
I'm using the space mostly for production (synths/guitars/pianos/beats) and mixing and some minimal recording (one to two mics at a time, mostly guitars and vocals, maybe a snare drum or cymbal overdub).
Thanks in advance for any feedback/help!
Emmett
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Post by rock on Dec 16, 2020 19:57:44 GMT
Hi, Welcome the the forum.
For your R38 batts, what are you trying to do? Isolation/sound attenuation from the floor above OR acoustic treatment of the basement? For isolation, the direction or the paper won't really matter if you're going to finish the ceiling with drywall. If so, consider RC channel and double layer drywall. If you really wanted to, you could tear/slice/peel the paper off but I don't think it will matter.
If it's for acoustic treatment, using the kraft paper facing into the room will act like a bass trap but reflect mids and highs. Facing the paper up to the subfloor above will allow the insulation to absorb all frequencies. If you want to do both, kraft paper down around the perimeter (about 2 to 3) feet will give you bass trapping there and the center or certain areas you choose can be paper up creating broadband absorption.
Keep in mind that the kraft paper is meant to be a vapor barrier so as long an both sides of the floor (above and below) are heated/air conditioned, you should be OK.
Regarding other treatment, if you've followed other projects cover here, you know there's lots or little you can do. It all depends on what you want. Acoustic measurements (with REW) of your untreated room will give you a baseline. Subsequent sweeps after various stages of treatment will inform your following choices.
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Post by emmett13 on Dec 16, 2020 22:02:12 GMT
Thanks so much, that's super helpful! It's meant for acoustic treatment. It's going to sit above the drop ceiling tiles that are already there (i think they are pretty basic, but not sure). I like the idea of putting facing side down for bass trapping on the perimeter, and maybe flipping it for more broadband absorption above my desk. The downstairs isn't technically heated (i.e. no radiators), but it's pretty much always warm—i guess because of how the furnace throws off heat? Not a homeowner and don't know much about these things;) There's a dehumidifier down there to help neutralize any dampness.
I have never done proper measurement with REW, but it seems straightforward enough—I may try it!
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Post by rock on Dec 16, 2020 22:54:56 GMT
Sorry, I didn't read your post correctly/completely. I disregarded the part about the drop ceiling tiles and my post was referring to the insulation open to the space below. When you cover the insulation with the drop ceiling tiles, I'm not exactly sure what will happen acoustically. I'm sure there will be a difference but you'll be negating a certain amount of absorption from the insulation with the drop tiles in front of it.
Here's where REW comes in. Measure each configuration and see.
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Post by Hexspa on Dec 17, 2020 18:39:22 GMT
With Doug's studio, they used a fabric ceiling with 1'-thick fluffy between the joists. 1' is roughly equivalent to 4" rigid at 125Hz. Like rock mentioned, having tiles in front of the absorber is an unknown so you'd have to measure. Pay attention to the upper midrange too to see how comb filtering either improves or doesn't. You can also do impulse tests but I haven't done one.
The thing about FRK is it's glued to the absorber itself and its semi-rigid. The system acts as a hybrid pressure-frictional absorber and helps bass response. Like I said, neither rock or I know how a ceiling tile will behave in conjunction with the fluffy. The other effect FRK has is reflecting above about 1kHz which you don't want at RFZ points.
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Post by emmett13 on Dec 18, 2020 14:27:18 GMT
Thanks, guys! I guess I'm going partly off of what Ethan suggests on his acoustics page: "Treating a "dropped" grid ceiling is even easier: Simply lay fluffy fiberglass batts on top of the grid, above the ceiling tiles. The thicker the fiberglass, the better. One foot thick R38 is perfect for this if you have the space. If you don't want to bother covering the entire ceiling that way, at least put fiberglass batts around the perimeter to treat the important wall-ceiling corners. And since the fiberglass is not exposed to the room and doesn't show, you don't need to cover it with fabric."
I imagine it effectively acts as a deeper bass trap than what the tile and space above it can otherwise provide? Maybe since the batt is above the tiles, I don't need to worry as much about the reflection above about 1kHz that you talk about, Hexspa? It sounds like it's a little unknown given the variable of the tiles. As far as installation goes, I mostly worry about whether or not I should stick to paper facing the room as a damp layer to mitigate slight temp differences between floors, but since it's generally pretty warm in the space despite being unheated, maybe it doesn't matter much. I did read here that one should actually put the vapor layer toward the warm side, so maybe there won't be that much reflection after all. "If you are adding fiberglass batts under a floor over a basement or crawl area and on the "cold" side of the floor, the vapor barrier, if there is one, belongs "up" towards the underside of the floor (or use unfaced fiberglass). To hold the insulation in place use wire springs, not a poly sheet stapled to the underside of the joists.I'm using it mostly for bass trapping around the perimeter anyway, and may build a couple of broadband absorbers for the walls. |
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Post by rock on Dec 18, 2020 19:31:07 GMT
1. I do remember reading that from Ethan but I had since forgot about it so I'm glad you found it. Sounds like he's saying or maybe suggesting that for the perimeter bass trapping "zone", you'll get similar performance with the dropped tile covering the R38 as if it were paper face down.
The difference I see is that in the center area of the room, you probably won't have the advantage of as much absorption the R38 would give you if it were open to the space only covered by fabric. Depending on the acoustic rating of drop ceiling tiles will tell you the mid and Hi freq absorption, which probably won't be bad. And like you say, you'll use wall panels too, which you would need anyway.
2. The issue of the paper is now moot from an acoustical standpoint. From a vapor barrier standpoint, since your basement is an occupied, "room temperature" space, this issue is also moot. So, be on the safe side and put the paper facing up to the floor and be done with it.
BTW, I have a bandmate who did his basement ceiling like you are planning. His ceiling is so low that he didn't want to use fabric and he had the tiles already anyway. His goal was mainly for sound transmission, which was somewhat improved but nothing like if he had put up drywall with resilient channel etc. He never took acoustic REW measurements as we just play down there. But, I can tell you his room is "tighter" sounding but not dead. He still has exposed concrete walls so this room could use more treatments but the ceiling work really made a nice improvement.
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Post by Hexspa on Dec 18, 2020 23:34:07 GMT
I think the main thing is upper frequencies since the tiles will probably not reflect much bass. If they're reasonably absorbent then I'm sure you'll get a good result. I'm inclinded to hypothesize that a bare or fabric-covered fluffy batt is more absorbent but I don't know for sure. Maybe you can find the data sheet and compare performance from 1kHz and up.
If they're less absorbent then they're possibly more reflective and that's going to give you a less good result for managing comb filtering.
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Post by emmett13 on Jan 5, 2021 18:36:54 GMT
Just wanted to say thanks to both of you for the feedback/insight! I shoved a good amount of batts, paper-side up, all around the perimeter and a bit over the console and it seems to already have tightened up the space a bunch. Didn't get to really bump any music over the holidays, but I'm looking forward to getting into some mixing in the coming weeks, and adding a couple of broadband absorbers on the walls to make it even better. Thanks again!
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Post by rock on Jan 6, 2021 2:59:50 GMT
So nice to hear you're happy with the improvement! Thanks much for letting us know; it's much appreciated! You'd be surprised how many we never hear from again afterwards.
Cheers, prosperity and good vibes (sonic and otherwise) in the New Year,
Rock
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Post by Hexspa on Jan 6, 2021 12:14:54 GMT
Mmm. Tight bass.
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