Building mix room in 2 car garage

Mix room design overview Hey Everyone Thanks heaps for all of the great info on the site. It gives me enough confidence to attack a project like this. I have been trundling around the web on sites looking for information on studio design for about 2 months now in preparation for my own project. I have found plenty of great information and am now ready to put it together for my specific situation and see how I go. I am still at the planning stage (guess I have been for a couple of months now) and hope to begin construction at the start of September. My budget is around A$4500 for materials and I will be building the room with some help from a few mates. The room will be constructed to suit 5.1 surround mixing, although initially it will be setup for stereo mixing only. The loudest I would be mixing would be 90dB. Generally I mix at a level around 83-85dB. The neighbours are close because I live in a residential area of Brisbane. The night time ambient SPL is 50dB slow response C weighted . Ideally, I would want to isolate the room enough so that any sound escaping from the studio is below the ambient level and not noticeable by the neighbours. I have access to another local studio where I can do my main tracking (drums, guit etc) but I imagine on occasion I will be tracking some instruments in the mix room. My monitors are Adam A5’s which I am initially going to mount on speaker stands that have a sand filled cavity (increase the mass). They have 2 x 25Watt amplifiers in each speaker and a rated 101dB SPL at 1m. I have a 2 bay 6m x 6m shed (that has steel C purlins with ceiling battens between them and some tin sheets screwed to the outside of that) that I am converting to a mix room with space left over for household storage. The room I will build at the back wall of the shed allowing the storage to be close to the roller doors for easy access. The ceiling height at the walls is 2.4m and 2.9m at the peak in the centre of the shed. I am considering a room size 3.19m wide by 4.66m long by 2.45m high (average). There are structural steel ‘C’ channels that reduce the allowable studio ceiling height to 2.2m at the walls and 2.7m at the peak. By reducing the room width to less than 3m (to fit the ceiling structure in between structural C Channels) I can get an extra 200mm ceiling height but the room dimensions would look more like 3m wide by 3.7m long by 2.65m high (average). After a little more reading I’m going to keep the width and not worry about the extra ceiling height. I can get some extra height by building the ceiling just under the Structural C Purlin. I am getting these room sizes from recommended room ratios from ‘RealTraps mode calc’ Materials and design I am thinking of building the outer leaf for the ceiling, east and north wall on the inside of the shed by screwing 19mm yellow tongue directly to the ceiling batten. The other 2 outer leafs will need to be constructed using 70mm x 35mm pine frames. The outer leaf will have standard 90mm ‘pink batts’ glued to it. Make the internal ceiling construction modular. The required roof truss beams will go in and then the 2 layers of gyprock will be fixed to the pine frame and screwed to the roof beams. Once screwed in 2” Rockwool will be fixed into the frame in line with the bottom of the roof frame allowing an air gap of approx 40mm between the insulation and the gyprock. Where the roof frame contains the shed structural C Purlin the 2 layers of gyprock will be fixed in line with the bottom of the roofing purlin and 2” insulation will be installed above the gyprock. This will be replicated on the opposite side of the ceiling so that it remains symmetrical. I am looking at a false floor not so much for the isolation but so that I can run cables under the floor to improve the appearance of the studio. Acoustic treatment At the moment I want to put I 2 slat resonators/diffusers alongside the mix position at a 6 degree angle. Superchunk bass traps in the 4 corners of the room from floor to ceiling. The north wall (behind the speakers) will be an inside out wall with insulation to absorb as many reflections from the rear of the speakers. I’m not sure what to do on the rear wall yet. Perhaps some curved reflectors? I've attached drawing that I have so far and (once I have worked out how to get my photos down to 700 pixels wide) will attach some photos so you can see what I can see. QUESTIONS (for now anyway) 1. Will standard Pink Batts be adequate insulation for in between the two wall leafs? 2. Should I put insulation between the yellow tongue and the tin wall and roof of the shed? 3. Should I build a fully floated floor design to help with isolation? If I don’t need a full floated floor I will just create a false floor to allow for cable access. 4. Will the Adam A5 monitors be powerful enough for the room size? 5. I have my speakers focussed at 60 degrees just behind where my chair would be. This makes the speakers (being 600mm off the wall) 1.84m apart. Will that be too wide and mess with the imaging?

Here are a couple of photos to give you an idea of what the shed looks like form the outside. There is one that gives you a look at about 1/4 of the inside of the shed shows what the internal construction looks like Cheers

"I am getting these room sizes from recommended room ratios..." Thing about ratios is that all surfaces are assumed to be flat as in not splayed at wall level or slanted at ceiling level like your ceiling is, so all bets are off ;) To do a false floor you have to take into account that the plywood will have it's on resonant frequency so effectively it will vibrate if care is not taken. Some have attempted this process using dry sand in-between the floor joists to damp the cavity/plywood. Others have used full sheets of Owens Corning 703 (or a comparable rigid insulation) to do the same thing, either one will work but the application is different for either method. You PDF file looks like the ceiling will be slanted from the left to right. If you can it would be beneficial to either change the sitting position to a wall that places the low side of the ceiling over you head, basically you want the ceiling, if not flat, to go up (higher) as the distance from the back of your head increases, to push sound equally away from you. Or to re-design the ceiling so that you have it slanted up and away from you rather than falling off from left to right or right to left, as it seems to be now. I don't quit understand your isolation methods at this point, how you are going to add mass to the thin metal exterior. I read it, but I am not on it yet. The exterior is going to be the hardest part to get mass added to, and it will need it. But, funny thing about metal buildings is they tend to sweat so you have to think about that as well as anything. You will notice that there is not venting anywhere on a typical metal shed/garage. Reason being that the design uses the door openings and the metal corrugation as a means to get some unrestricted air flow. So if you restrict these areas, you have to take your materials into consideration. Also, that metal shed will not support as much as you might think it will and it >reads< like you are well on your way to overloading the ability of the shed to support itself by attaching more weighted material.

Hey xSpace Thanks for your thoughts. I'm trying my hand at Sketchup to try and explain better what I am seeing in my head. I'll post the results shortly Cheers Brett

Hey xSpace Alrighty.....so here is what I have come up with. The vision file I was using initially went corrupt on me so I had to start from my original measurements and recalculate everything. That being said, I have had to learn how to use sketchup which I have found to be a great program. I have been able to get a lot of the design done up in Sketchup put I am unable to upload the file because it is 3Mb. I have tried to purge in the model window but it only saved me 300kb. I have made each section a component but it looks as though it keeps all of the previous components in the file for when you explode or edit a component. Any thoughts about how to get the file size down? If I can't get the file size down I could use dropbox to get the sketchup file to you if you need it. Here are some images This first image shows how the room will be orientated in the shed. The roller doors are at the open end of the frame. This second image shows the frame work for the inner leaf of the wall with the acoustic treatment. At the moment I am thinking superchunk bass traps in the four vertical corners. I am thinking of also putting a superchunk bass trap on the front and rear wall/ceiling corner as well (not shown in the drawing). There are broadband slat resonators on a 6 degree angle to keep the first reflections away from the mix position. The ceiling above the mix position is angled at 10 degrees. On the 180mm x 35mm beam that runs through the room below ceiling height I was thinking of putting mid frequency absorption on both sides that will also help with and reflections from this beam. The front inside out wall will be all absorption with 4" insulation. I am going to try and get some insulation with a density around 48kg/m3 to try and absorb as many frequencies as I can from the rear of the speakers. I'm not sure what to do on the rear wall yet. I am thinking there might be too much high freq absorption in the roof so thinking I might need some plastic over the front of the bass traps or maybe some curved reflectors on the rear wall? The ceiling will be modular with 2 layers of soundcheck gyprock and 2" insulation on a pine frame. These will get screwed in between the inner leaf ceiling joists so that the gyprock is level with the top of the ceiling joists. There is one section of the ceiling where the shed frame protrudes below the top of the ceiling joists. To keep things symetrical, the sections of the ceiling closest to the wall will have the modules mounted so that the gyprock is level with the bottom of the ceiling joists. Should I make a curved reflector for these two sections to balance out the rest of the ceiling being absorptive? This final image is the top view of both leaves of the wall. The outer leaf is 19mm yellow tongue and the inner leaf is 2 sheets of 13mm soundcheck gyprock. There will be fibreglass (pink batts or similar) in the cavity between the two leafs of the walls and the ceiling. The outer leaf of the ceiling will be screwed to the existing ceiling battens allowing a gap between the yellow tongue and the tin roof and walls of the shed. Should this cavity be filled with pink batts? I am going to ask the owner for the plans of the shed to make sure that the yellow tongue doesn't overload the shed framing. If there is a problem I will have to add extra support somewhere At this stage the floor panels will go straight on the concrete slab to help with the budget. Let me know if you need any more info/clarification. Thanks again for your thoughts Cheers