Recording Studio Design in Cali, Colombia.

Ok now let's start with the panel construction. I designed the frames first in sketchup wich is great and so acurate. After the designs where finished I ordered all the parts and have them pre cut in order to assemble them. All the height sizes are 1.22 and the widths are 61cm x 5cm (Hi Absorber), 80cm x 10cm (Mid Absorber) and 80cm x 15cm (back wall broadband and cloud absorber) Also there are Corner Bass Traps 61cm x 28cm deep. All will have clothing + 1" thick rigid fiberglass layer, then 3 1/2" glasswool, and finally a layer of expandible polystyrene (the material used for packing) wich is porous too but retains the small glass particles to scape from the back of the panel and float in the air. My theory is that the deepness of the cavity and the different thickness and density of the materials inside the frame will make an excellent panel absorber for all the frequencies. Of course I will need to build slats for low mids, and maybe some hangers for the super lows. My plan is to reduce the reverb in the rooms and later test and treat individual anomalies like standing waves or specific room modes with a dedicated panel absorber tuned to the annoying frequency. I used 18mm thick melaminic MDF for all the panels.

Here we have the sofa, the studio desk I designed in sketch up, and the cutting of the layers of rigid fiberglass.

Heavy rain and cloth frames. Yesterday we had a terrible rainstorm here and an incredible flood never seen before. All the water ducts collapsed and the streets became rivers!!!.

Here I'll explain the construction of the cloth panel. I used a fabric that is used in upholstery. One coat is in a color and the back has some kind of rubber or sinthetic layer that makes this cloth ideal because it prevents de glassfibers to scape and is porous enough to be acoustically transparent.

Here I will explain the building of a corner basstrap. First cloth frame inside panel frame, then 1 layer of rigid fiberglass, then levelor sticks to create an air cavity, then 2 layer of fiberglass, then glasswool, then expandible polystyrene.

Continuation of the Corner bass trap panel

That's it for now. All the other panels are pretty much the same construction. All comments are welcome. See you soon. Ed. Next. Building of the cloud with the lightning.

it all looks, really great. Good craftsmanship! Great photos. Keep'm coming. couple o' comments: 2x 1" thick wool for a basstrap is waaay to thin. You need atleast 4" (10cm). The pink insulation on the back of the rigid panels, how thick is that? And what's with the hardfoam backing? (EPS/polystyrene) It has no acoustic value to start with. It would be wiser to put that on FRONT since it's a basstrap and you wanna keep it for low frq only (the polystyrene will reflect mid/high frq and therefor acts as a low pass filter) For a basstrap to work it needs volume in wool. thicker is better.

Ro wrote:

it all looks, really great. Good craftsmanship! Great photos. Keep'm coming. couple o' comments: 2x 1" thick wool for a basstrap is waaay to thin. You need atleast 4" (10cm). The pink insulation on the back of the rigid panels, how thick is that? And what's with the hardfoam backing? (EPS/polystyrene) It has no acoustic value to start with. It would be wiser to put that on FRONT since it's a basstrap and you wanna keep it for low frq only (the polystyrene will reflect mid/high frq and therefor acts as a low pass filter) For a basstrap to work it needs volume in wool. thicker is better.

Hello and thanks for looking my post. Ok. The problem is that I have to do what I can with what I have, you know what I mean. Of course it would be great to put 4 layers of 1" rigid fiberglass but my budget only allows for two. So I decided to use the pink insulation wich was a leftover from the Isolation made in the ceilings and studio front wall. This pink glasswool is 3 and a half inches thick. I decided to used the polystyrene (hardfoam) in the back not for his acoustical value but for closing the back of the panel in a cheap way. I want to prevent glassfibers to scape and float on the air. I hope it will do nothing more that sealing the back and because it is only 1cm thick I guess it is not much of an acoustical barrier for high frequencies. Ed.

Adding the pink insulation was a good idea, it doesn't really matter if it's rigid or not. 3,5+2 equ 5,5" -> very good. There you have some volume. :) I'd remove the polystyrene from the back to keep an open back, the trap will benefit from the (open) space behind the trap.

the traps look great pcmusicpro. The clean look that you got on the front using the 2nd smaller frame to pull the cloth tight is a good idea which I will steal! How is the room any way? what was itsounding like before?

lilith_envy wrote:

the traps look great pcmusicpro. The clean look that you got on the front using the 2nd smaller frame to pull the cloth tight is a good idea which I will steal! How is the room any way? what was itsounding like before?

Ey I'm glad you like it. In the past I had a small home studio in the same space. The only treatment I did was to put some foam, then after reading a lot in this forum I realized that I had to control the bass and mid frequencies too. Later I went to Argentina to study music production and sound for films, after finishig I returned to my country and decided to star over again with the studio in my appartment, but this time I wanted to make it better, but my budget was tight so I decided to go for the panels. I will add some others and build a couple of slat resonators as soon as I get more money. The room was very reverberant, wich is logic since it had no treatment at all. Today I hanged all the panels and the reverb time decreased a lot. Still haven't done any measurements or exhaustive tests but as soon as I finish I will test thoroughly and post the results. Finished too the cloud but it seems too heavy so I'm testing if my ceiling can handle the extra weight. I'll post new pics soon. Ed.

Hello all. It's been quite a while since I was here. I finished the first part of my studio construction and now I want to continue with more sound proofing. I did some tests and noticed especific problems in some low frequencies. I suppose those are standing waves or problematic room modes in my studio and control room. I don't have much time so I will be slowly puting results of the tests to let you know what has been achieved regarding sound proofing the rooms with the panels I build a couple of years ago, and what can be done to improve even better the spaces. As I said before, I have some low frequency issues that I'd like to try to resolve or at least to control a little. Maybe I will try some bass hangers and Helmholtz resonators to control in the range below 300Hz. I've been testing with a normal Large Diaphragm condenser mic set in omni directional polar patern. I'm thinking of purchasing a measurement mic, a cheap one. What do you think? is it worth to buy it or the large diaph condenser is just ok? Well thanks for reading this, any help, as allways, will be greatly appreciated. Ed.

are you trying to acoustically isolating or acoustically treating the room? if you have sound leaking out and you do not want that, then you should work on the isolation. if you have the isolation you need and you are concerned about the room response, then you should work on the treatments. i'm assuming since you mention low frequency and panels you built that you're focusing on the treatment. using a large capsule omni mic will be fine for testing.

gullfo wrote:

are you trying to acoustically isolating or acoustically treating the room? if you have sound leaking out and you do not want that, then you should work on the isolation. if you have the isolation you need and you are concerned about the room response, then you should work on the treatments. i'm assuming since you mention low frequency and panels you built that you're focusing on the treatment. using a large capsule omni mic will be fine for testing.

Yes, yes, I mean to acoustically treat the room. Regarding to isolation I did some with acceptable results. I still have to treat a window in the living room that leaks a lot of street noise into the studio, and reinforce an acoustic door which is well built but leaks noise at the borders, between the frame and the door. And I was thinking on putting a second door in the corridor in order to obtain more isolation. I need to do things here and there but one at a time, this is a work in progress but in the meanwhile I have to use it to make records the way it is. I've had good results recording and the mixes translate well outside the studio but with a better room response and a little more isolation I'm sure it would be more comfortable to work here. I'll post some pics soon. Thanks for your answer.

I will start tomorrow with some test before and after treatment. I will empty the control room, take all the panels I've made in the last years and do some test to know the most I can the problems of the room "as it is" then I will put the panels again in it's place and make the same exact tests following the same steps and see what changed. My tools are: pink noise file at -20dBFS Sweep tone from 20Hz to 20KHz Test tone CD by Real Traps http://www.realtraps.com/test-cd.htm American Audio digital Sonometer tipe II Studio Projects B3 Large Diaphragm Condenser in omnidirectional polar patern The test: My plan is to star with Pink Noise Test. I will measure 85dBC (should it be dBA curve better???) with the pink noise file at the listeners position, then I will record the response heard by the micophone and analize it with a frequency analizer (Waves Paz Analizer.) Do you reccomend a better or more accurate one? The next test is to play the sweep tone, record it with the mic and see what's changed The last and more time consuming test is the one described by Etan Winner here http://www.realtraps.com/test-cd.htm. Questions: Are this tests ok? Are better, more acurate tests I can do with the tools I have? Can I improve the tests I described before in order to make the results more accurate? Any help will be appreciated. Thanks. Ed.

check out REW (Room EQ Wizard) which will help more, as well as provide more details later - like reflections and such.

Thanks I downloaded REW and I'm in the process or reading the manual. Gonna wait until everything is clear to start with the tests.

Hello people. Well, I'm back and with some pics and REW graphs. I learned more or less to use REW, I callibrated my sound card, and my levels and I did some tests. Here are the results: First I'm going to show you the response of the room with the panels out, this means empty room. The only panels I did not remove where the cloud and the back wall because they where too heavy for me to move them since I don't have any help here. Look at the pic of the room, then the REW response graphs. You can see the large diaphragm mic I used at the mixing position.

Ok those where the results with the room empty. Now here we have the results witl all the panels I built inside the control room and at their position. This is where I am right now. I want you guys please to check the response graphs and tell me how do you find them and what should I do to improve the curves. I did many more tests than those posted here. In different positions than the mixing sweet spot and the results in the low frequencies where more or less the same you see here. There are some peaks and nulls and I'd like to know what can I build (resonator, membrane absorber, etc) in order to have a more focused and controlled response. Should I upload more pics and do further tests just let me know. Ok here they are:

Hi. Is there anybody out there? I think the graphics are interesting and I can see that the treatment I did effectively controlled high frequencies and tamed a little some mids. But I can see various issues in the low and mid/low side. I guess that building a broad band Helmholtz resonator with slats could help. But I'm just guessing, and I need an experts advise. Any help will be appreciated. Thanks. Ed.

I think you should start with some more bass-absorbing, to begin with. Your current corner absorbers are very "light", consider doing a full corner fill. Top to Bottom and preferably fully stuffed (aka super-chunk). Corners are the best place to control that low-end dynamics I see in your plot. The very low end can be addressed with a tuned resonator if you like.

Looking at those photos, it seems you are not using full range speakers for the test, so everything below about 100 Hz. on those graphs is most likely not valid. Anyway, it looks like you don't have enough bass trapping in that room yet, and what you do have is not in the optimum locations. You get the best effect by putting the bass traps in the tri-corners (a corner where three surfaces meet, such as wall-wall-ceiling, or wall-wall-floor). Theoretically you get an 18dB boost from tri-corners, and only 12dB from normal corners, so simply lifting your traps up to the ceiling or sliding them down to the floor might improve things. But you still need more of them, and they should be deeper, too. There also seems to be something wrong with the way you have REW set up, since the waterfall plots never get down much below 30 dB, and you have peaks beyond 300 ms. even at 250 Hz, which seems unusual: Do you have a lot of ambient noise in there? Anyway, I would add more bass traps in better locations, and measure again.

Ok. Understood I'm going to begin by improuving mi front wall and the front corners. I have a space of 40cm x 65cm with 45 cm deep over the corner traps and 77 x 65 x 45 cm deep under them. I will fill that completely with rockwool and cover it with a frame and a cloth for aesthetics. That way I will have a long bass trap from floor to ceiling in each front corner. In the front wall I will try to put 4 inches of rigid rockwool and acoustic foam for a nice look and a little more absorption. I have an untreated space on the side walls between the floor and the panels that are already installed. Would that be a good place to install slat resonators? I could build a couple of them 1.60m long x 65cm high x 20cm deep. and put them in every side. Your are right, the speakers are not full range, and you are right too about ambient noise because with everything closed the sonometer reads between 30 to 35 dBA of noise floor inside the studio. The studio is built at an appartment near an avenue and I can't do much more for isolation. I'll post some pics later. Thanks for your answer. Ed.

Hello Well I've been thinking what to do to increase the height of my corner bass traps. I have 4 bass traps that are 80cm x 1.25m. What I have in mind is to put one trap over other thus having two 80cm x 2.50m corner traps in the control room and later I will replace the traps in the recording room with new ones. If you look at the previous pics you'll see that the traps are built with 2"rigid fiberglass and less denser fiber glass behind. When placed in the corner there is still a small space of 20cm between the wall corner and the back of the panel. Should I fill that space with absorptive material in order to increase the effectiveness of the corner bass trap? CONTROL ROOM FRONT WALL Ok that's all regarding the corner traps. Now what do you think about front wall? as you will see in the pic I have no treatment in the front wall, just my 32"LCD tv recently placed. How thick should be the treatment in the front wall? CONTROL ROOM SIDE WALLS I have at my right, from de mixing position, the studio window, which I can cover with a movable panel I take from the recording room when mixing. I have a 10cm thick 80cm x 1.25m panel on my left and lighter panels (blue ones) beside them. The space behind the window and over the window is untreated. Are this good places to put slat resonator panels in the future? CONTROL ROOM BACK WALL In the back wall I have the couch which I guess is doing some bass trapping by itself (it's built of hi density foam, wood and fabric) and over it I have the largest panel I could build. It's 15cm deep x 1.25 high x 1.65m. It is fully stuffed with 2 laters of 1" rigid fiberglass and less dense fiber glass. Is this treatment of the back wall enough? Ok here are the pics.