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Post by chollus on Jul 3, 2018 11:45:17 GMT
Hi Ethan, Hi Everyone, First of all, excuse my poor english. I m from france and i have a home studio in a basement under my own house. Dimensions are not great at all : 21’4 x 11’10 and ceiling about 6,5 ft (i know, i know...) I play and record jazz, acoustic kind of music in it. Like a lot of guys working in such a room, i have troubles with the modes of my room and especially with low medium ones. For me, the worst thing happens berween 90hz and 250hz. I can hear it even when i m speaking... So, obvioulsy, the frequency response is uneven, hard to make real music, but nothing fancy, only physical laws. The walls of my room are made of big stones and the low ceiling by their nature can t be drilled. This is what i ve already tried : - 2 «* bass trap*» on 2 corners behind speakers, 4,72 inches thick, (135x60 cm) with rockwool alpharock, density : 70kg/m3. Results : less uncontrolled resonances at low frequencies but too much high absorber -Idem behind the drums but only 3 inches thick. - a more few broadband panels - i tried to absorb ceiling with lighter material just for testing and checking differences, once again a bit better. I faced the kraft to the floor, much clarity. But still this mask over low/low med. During last month i have gathered a lot and lot informations by reading all i could find about this subject...so this is what i am thinking to do... I m planning to build about 10 basstrap with semi rigid fiberglass Isover gr32pp with kraft who is about 30 kg/m3 of density, 135x60 cm, and from 7,8 to 10,6 inches thick...(where i live it s very hard to find medium density like 703, it s only low or high) For the ceiling, the same iSover , but only 3,9 inches thick cause i don t have so much room between ceiling and woods brackets. Above drums i have much room so i could go for more thickness If i can, i will space with a gap, and i will try different placements, with some measuring... Do you think it s a good way to do in this kind of room... My goal is to have a correct sound in my room in order to focus myself on playing and recording... There are son pictures ( sorry for all the stuff, cleaning will be a full part of the process) And thanks a lot to someone who could help me!!!!! I looking for all advices and ideas, and i won t give up
this is a dropbox folder link in which you can find pics of my room, measures with rew (captures ans .mdat and sample sound)
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Post by Michael Lawrence on Jul 3, 2018 12:34:09 GMT
Hi Chollus-
Welcome to the Audio Expert forums. Your English is fine, I understood you perfectly.
There are others here who will be along shortly to give you better advice, but I can offer you a few things, at least.
The Kraft paper backing on rigid fiber becomes reflective at high frequencies, so you can absorb the lows and not dampen the highs too much.
The bass traps you tried are likely too thin to do much good at the frequencies you mention, so thicker is definitely the way to go.
As Ethan likes to say, you can use rolled-up carpet or bags stuffed with pink fluffy fiberglass insulation as a test, to see what the extra absorption will do for you, before investing a ton of time and money in the project. Be careful not to make the room too much smaller than it already is. Doesn't matter how good it sounds if it's unusable.
Lastly remember that tons of great recordings have been made in non-ideal rooms, so just do the best you can, and don't worry too much about it.
I'm primarily a live audio engineer, and we don't have the luxury of treating our rooms. We work around it: moving a mic closer to a source by a factor of two (maybe 24cm to 12cm) increases the signal-to-noise ratio of the recording by 6 dB. Go to 6cm and you've effectively "turned down the room" by 12 dB. So you can never get a room this small perfectly flat, but you can improve things, and you can decrease the influence of the room significantly by carefully choosing mics and mic positions. Placing mics while listening to the source through headphones can help as well.
Best wishes.
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Post by chollus on Jul 3, 2018 13:03:27 GMT
Hi Michael and thanks a lot for your answer full of informations...indeed , today i know most of my absorption has been made to thin’ that s why i m planning around 10 bass trap around 10 inches thick in the room and a more thicker absorption on ceiling too, but i m wondering if 30kg/m3 density could do the job..i guess yes...?
I appreciate your philophy and i have to say, i think the same way but even if i know the sound of that roomm won t never be high class, i want to be sure to have done all i could to optimize it...
Thanks again , really!!!!
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Post by chollus on Jul 3, 2018 22:17:48 GMT
I have choice beetween 2 mineral wool :
1- isover gr32 ~30k/m3 semi rigid fiberglass
2- Rocwool « rocfacade » semi ridid 39kg/m3
I know that more than density, it s the gas flow resistivity who is important, but impossible to find some data, all i know is that both of them are >5ka s/m2 but it could be infinite...who knows....
Any advice?
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Post by Ethan Winer on Jul 4, 2018 16:36:54 GMT
I got your PM, but it's better for me to answer here.
You are correct that the real issue is gas flow resistance more than density, though the two seem to be related. The good news is both of those materials work just fine. For thinner panels less than two inches thick (5 cm) higher density is a little better. And once you get to 8-10 inches thick (20-25 cm) lower density is fine and less expansive. But they all work very well, especially if you make bass traps thick enough. So buy whatever costs less, and just avoid the really lightweight stuff unless you're able to make the panels 12 inches thick (30 cm) or more. Then the fluffy insulation is fine too.
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Post by chollus on Jul 4, 2018 17:46:39 GMT
Ok, mille mercis Ethan ,for the input. so it will be 20 cm of isover, with kraft facing, with a 10 cm gap. before starting to build, i have 2 more questions for you : 1 - each isover panel come with kraft on one side, i m going to combine 2 panels to reach 20 cm, is it a problem if one of the two krafts is in the middle of the trap? (This way i could choose later to face the trap kraft or not as an hf eq) 2- i would li ke to absorb most part of my ceiling (who is very low 6,5 feet/ less than 2 meters) to make it the most sonically invisible. The trouble is that i can t really drill it, but with some wooden brackets and a bit of imagination, i managed to insert pannels of semi rigid isover of 75 mm and i think i can go to 100 mm; so my question is : with so little room beetwen brackets and ceiling what kind of material should i use, low density, higher one (i can get 27, 39, 70 kg/m3) ? Once again thanks a lot, i m so excited to start the game!!!  |
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Post by chollus on Jul 7, 2018 9:52:45 GMT
Building started Attachments:
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Post by Ethan Winer on Jul 16, 2018 16:41:59 GMT
You do not want paper in the middle between the panels. So peel that side off.
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Post by Deleted on Jul 17, 2018 15:03:38 GMT
You do not want paper in the middle between the panels. So peel that side off. What are the effects of having Kraft paper in between layers of fiberglass? I have in my panels papers in between... For example, I have 4inch fiberglass then paper, then 2inch fiberglass. |
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Post by Hexspa on Jul 17, 2018 19:13:23 GMT
You do not want paper in the middle between the panels. So peel that side off. What are the effects of having Kraft paper in between layers of fiberglass? I have in my panels papers in between... For example, I have 4inch fiberglass then paper, then 2inch fiberglass. I've heard several times that it's not the ideal situation. Still, I've never seen any hard evidence to the contrary. If you're up for it, you can test it for us. |
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Post by Michael Lawrence on Jul 18, 2018 0:01:18 GMT
I'll venture a guess. Disclaimer: It's a guess.
Acoustic absorbers are made of open-celled foam so air can flow through the material. This causes friction with the air molecules and slows them down, in a manner of speaking. That's why fiber is classed a "velocity absorber."
A layer of FRK halfway through a 4" panel means that airflow can only get through the first 2", reducing its effectiveness.
Eh?
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Post by Deleted on Jul 18, 2018 9:31:49 GMT
I'll venture a guess. Disclaimer: It's a guess. Acoustic absorbers are made of open-celled foam so air can flow through the material. This causes friction with the air molecules and slows them down, in a manner of speaking. That's why fiber is classed a "velocity absorber." A layer of FRK halfway through a 4" panel means that airflow can only get through the first 2", reducing its effectiveness. Eh? This maybe true for higher frequencies, but I would "guess" bass will go through that thin frk paper easily. I have no idea why did I put that paper in between, at first place. Guess I was inexperienced. Maybe I thought it helps with bass, lol. This "technology" is only used in my very first panels, which are still being used in my room.. |
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Post by chollus on Jul 18, 2018 11:05:25 GMT
Damn, i had time to build 8 of this before reading your answer obout kraft paper in the middle...like Pasim, i was figuring out that the paper in the middle wasn’t a problem for the low frequencies flow... Is it a problem? ![]() Question about ceiling, only have 10 to 15cm free room for absorption...should i go for low density or higher density with that thickness (20, 30, 45, 70 kg/m3?) Thanks Attachments:
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Post by Michael Lawrence on Jul 18, 2018 12:41:30 GMT
I'll call Ethan today and ask him if I get a second.
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Post by chollus on Jul 18, 2018 13:04:02 GMT
Oh thank you so much Michael...really!
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