Recording space: 24'Lx16W' with 8'H ceilings; concrete floor: The room is partially anechoic, with about 8" cellulose insulation covering two-thirds of the walls and ceiling. Rubber on the floor. I added reverb to create the space I wanted, using the TC Electronic Powercore MD3(VSS3).
I am tearing out all the cellulose insulation, to add more layers of drywall. Now is my chance to try some experimentation. I want to try a more live recording area. If I don't like it, I can always add more absorption and go back to anechoic.
The Experimental Plan: ALL horizontal ceiling corners covered with 12"x12"x17"cellulose insulation (House wrap covered)(Two are 24'and two are 16' long)
ALL vertical wall corners covered with 12"x12"x17"cellulose insulation (House wrap covered). (Four 8' high)
Eventually will also additional panels to the walls and ceiling. We can cross that bridge later.
Questions: 1. Any reason to add 703/705/FRK/alternative surface, to the hypotenuse (17")? 2. Am I wasting time and should just go back to anechoic and keep creating the space in the box?
Perhaps I did not provide enough info... First let me say I appreciate your willingness to help teach me, and I will try hard to get myself in line and be teachable Missing a few things: My apologies, I have updated my profile. I am from the Chicago suburb of South Holland IL. USA.
History and goals: I have mixed music at church for about two decades. I also did live music for about a decade, but my back could not handle carrying all the equipment (two back surgeries), so I switched to the goal of a recording studio. My goal is to help bands that can't afford much, from recording all the way to mastering. I want to do charity for church bands, and poor people to crate demos. I know electronics, and IMHO know how to mix and OK for mastering, but the sound treatment is not my strong suit and I am requesting help.
The space is a garage 24'x24', which my wife said I could have for the above goal. I sectioned off 5.5'x24', where I and the band members are at while recording. The actual recording occurs in the 24'x16' space. The dimensions don't add up perfectly as there are double 2x4 walls separated by 1" gap on the outside walls. The sectioned off 5.5'x24' space also has a double door airlock space to the outside world. No windows anywhere.
Q: Define the purpose of your room. What do you plan to do in there? A: Record bands in the larger space 24'x16'. Mix and eventually master in the same larger space after the band departs. This is for charity demos. Unfortunately the recording area is 16'x 24' ish.
Q: Define your isolation. How much isolation do you need, in decibels, to the outside world A: As much as possible, that is affordable, and is value added for charity. Does 50dB sound reasonable for road noise? The road behind my recording studio, is about 30' away, with traffic noise. Not trying to keep studio noise in, but I am trying to keep traffic noise out. I can hear the traffic on sensitive condenser microphones, about -50db down. This has me concerned. I already have double 2x4 walls separated by 1" gap. The outside wall has only one layer of 1/2" OSB. On the inside walls, I am planning on increasing the existing one layer to six layers of 5/8" drywall. I have already purchased enough drywall and green glue to do six layers total of 5/8" drywall.
Q:So it is a perfect modal resonant chamber, tuned to 70.6 Hz, with major, huge, extreme modal issues? Why did you choose those dimensions? It's about as bad as it can be. Width is exactly twice the height, and length is exactly three times the height. You have created the perfect acoustic storm! A: Charity is what I have, and the space is what I have. What can I do to improve? I can completely remove the dry wall ceiling, and gain about 4 more foot height peak of a trapezoidal roof. Peaked at the center and angled out. Should I remove the ceiling and raise to the roof rafters? I will if it makes a difference. Or is the space not useable? It appears I should solve this before anything else. I am not trying to make money. I am willing to do whatever it takes to help others, but I am not rich enough for a new space. I want to make a difference and help others in this life, if I can. I thank you for trying to help me...
Can't really help with your acoustic treatment, but with your unwanted sounds getting in, your ceiling could be the weak spot?...but not sure exactly whats its all made of? I did a build where i Spent more money on the walls and neglected the roof. It showed....im originally from the uk, so not sure of what your buildings are made of?...regarding weather, you have a good deal of insulation and from memory Chicago can get cold, im battling with heat and aircon units ATM so thats all new to me! Im guessing you could do a lot with your gap in the ceiling but i can't visualise it, im more of a diy builder/designer, so that's where my ideas tend to lead, pictures might help you get an answer from the acoustic experts. Sorry I can't be much help....
On the subject of isolation, Rod has some specific techniques you should learn. Among other things, if you're rebuilding your space, you can tweek your inside dimensions to optimize modal distribution.
The reverb you'd get in a 24x16 foot room is probably not as good as your digital reverb unit. So I wouldn't expect removing insulation to improve the sound. However, you might consider moving some of it to be spread around more evenly. A combo room used for musicians and mixing is usually more treated at the mixing end, and the band behind you can have a little more reflective surfaces. But isolation will be the big problem. Real isolation requires construction, which is expensive and makes your space even smaller. But if minimal isolation is enough, then this could be viable.
Note: I have created two picture links, in case one does not work. All drawings are in inches.
I purchased the calibrated microphone Dayton Audio EMM-6, and paid double the price to get the better calibrated version from Cross Spectrum. I used REW software, completed loop calibration and also the calibrated microphone configuration. I did notice a significant difference between the Neumann U89 and the calibrated Dayton Audio EMM-6 measurements. Being obsessive, I purchased a 3rd microphone , and it appears the calibrated EMM-6 is accurate.
Please note for these measurement, no corner trapping, as I have recently torn it out. I have some wall and ceiling trapping, which will be torn out and redone. From the waterfall I see huge issues at 34Hz and 51Hz.
I will do additional REW measurements as the work progresses.
I assume I can't get rid of the 34Hz and 51Hz with this plan. After the above is complete, I plan to build some Helmholtz bass traps in the attic for the 34Hz and 51Hz. I have room. I will also ensure the attic is sound resistant as Pingpangpong suggested. I will do additional REW measurements as the work progresses.
The skinny side room is the first task, so I can get the electronic equipment reinstalled. 2nd is the large recording space. (See studio pics)
Also just a FYI, I am in the process of reading the "Master Handbook of Acoustics" 5th addition, by F. Alton Everest & Ken C. Pohlmann.
Thoughts? Am I on the right track, or doing too much bass trapping off the start?
Being obsessive, I would rather error on the integrity side.
Question: For the wall trap drawing design, each is 24" wide which is symmetrical. Should I do asymmetrical? One trap at 24"W, another at 28"W, another at 33", another at 38" etc... Asymmetrical make a difference? Hmm...
The long side Equipment Room (almost a hallway), is only used to keep the mic's from picking me up, and typically the scratch vocal. Equipment Room is only used during recording in the large room. Never ever used for mixing. The Equipment Room ceiling studs are almost done. The studs are only for absorption traps. Time to do a REW measurement in the Equipment room, before traps. Next post REW measurements before traps. I suspect the Equipment Room may act as a low frequency resonator, and even more so through the Equipment Room window, so I am doing some extra care in the Equipment Room treatment. Plus, although I don't care about the scratch vocal quality occurring in the Equipment Room, it would be nice if scratch VOX doesn't sound terrible. So off I go to do extra care in the Equipment Room. Next post Equipment Room REW measurement. This should be scary, 62"W x 234.5"L x 93"H. :-)
Last Edit: Nov 21, 2018 21:38:54 GMT by grega60438: Changed Control Room to Equipment Room to make more understandable
I can't find the noise reduction coefficient ratings for blown-in cellulose. Neither can I determine the thickness of it. Symmetrical is better but I'm not sure what you mean. I just don't really understand this thread lol.
I have double walls separated by an inch gap, and I am adding more layers of drywall and green glue to improve isolation, which is the reason for the studio rebuild. But not the purpose of this thread. The purpose of this thread is about absorption. The actual blow in cellulose, brand name Regal, I bought in the USA, is very cheap at about $6 US a bale. I have been able to find a post stating "cellulose (C2) 90 mm blown 33000 mks rayls/m. 90mm is about 3.5" thick for the USA. For shallower depths blown cellulose as a higher Gas Flow Resistivity (GFR) IMO is acceptable, but not always the best candidate for deeper depths IMO. I am using blown cellulose for shallower depths, and will switch to lower GFR insulation for deeper depths, such as super-chunks. As for further clarification of the purpose of the post, I see much theory posted, but wish there was more before and after data. I will log the results before and after treatment, to hopefully help others. I am using REW software, calibrated microphones, and calibrating the signal path, in an attempt to offer credible data. I will try and be as scientific as I can. I do not know it all, so I am also posting here hoping for any recommendations to improve the design in progress, and also any testing.
Thanks for providing all the images. I was wondering how you were going to contain the cellulose and I see you're using Typar. I don't think typar is acoustically transparent (can you blow through it?). I would imagine you want mid/high absorption on the walls so something like burlap or speaker grill cloth would allow that... but maybe I don't understand exactly what you're doing there?
Something easy to change and experiment with is the mic'ed drum set location. IMHO, it's best to get mics away from boundaries, even if they are treated so maybe consider trying setting up the drums closer to the center of the room for recording. Placing absorbent panels (with no backing) around the set will attenuate any reflections too but you may not need them...Just a suggestion.
Your wall construction for Isolation looks lopsided in that you only have one layer of OSB on the outside and four sheets of drywall on the inside. I really don't know but it just seems most of the examples I've seen are more or less balanced. If you can't add more mass from the outside, you can add mass (drywall etc.) from the inside of the OSB cut to fit between the studs. You can also isolate your inside stud from the floor with compacted mineral wool.
One question about the wall, I know what a furing strip is but what is the CLIP? From my understanding, you should only have two mass components. The OSB would be the first and the four drywalls would be the second. If the four are isolated (2 + 2) by the CLIP and FURING, it is my understanding that their effectiveness will somewhat negated and the mass would be better utilized on the outside wall or at least combined to one solid mass on the inside. But I have to admit, I'm certainly not the expert and not completely sure so if you can help me understand, I'd really like to know.
Answer to Rock: Typar is a woven weave housewrap. I understand and I am OK with, Typar reflecting higher frequencies as long as it passes the lower frequencies. The wall drawing was rev 1, and I am leaving out the isolation clips on rev 2, as the double walls are already built separated by 1" gap. I plan on focusing on the inside walls this year and next year will review options for the outside walls. I have been considering alternative locations for the drums, thanks for the recommendation.