New recording studio in Carleton, QC

Hello everyone, First of all I'd like to thank everybody on this forum who took the time to share their knowledge. I am already deeply indebted to you all for what I've gathered from my reading on these pages so far. Thank you. A little bit on myself: My name is Alexis, 23 yo, from up north in Quebec, Canada. My first langage is french, so my interventions might be confusing at times. I'll try to be as clear as possible. I currently study recording and mixing for both live and studio applications. I have developed a passion for architectural acoustics over the past few years and studying recording has led me to studio design and thus, to this forum. The project: I've been involved over the past month or so in the design of a recording studio which will be located in Carleton, QC. This little town on the shore of the St. Lawrence river is truly a beautiful and inspiring place. It hosts a quite renowned blues festival in the summer and so music is well alive there. Unfortunately, it lacks adequate recording facilities... but this is why were here! The studio is to be built within an extension to an existing commercial building. Separating the existing structure and the new one is a stairwell, which serves as a link from and to the existing structure and the new one, as well as between the two floors that will be built in the said extension. The extension hasn't been built yet, but general plans for the constructions have been produced by the architects. They thus comply with the local building code and other legal requirements. As we will see, there may be a possibility of slightly modifying those plans to suit the need of the studio. The first floor, which will contain the recording studio is reached by going down the stairs, so it is actually halfway into the ground. The second floor will contain a video post-production facility, so sound-proofing between the two levels is important. The budget: I have not yet received a clear info on this subject, but I was told by the owner that he was willing to pay what it takes to get the quality he wants. He has set-up financing plan few years back and seems confident he can manage. Of course, I try to keep the costs as low as possible without compromising the quality. The dimensions: The dimensions we have to work with are as follows: Height: 13' 10'' from slab to upper-floor support beams Length: 40' exterior to exterior, or 38' 8'' interior to interior (because of the width of the foundation walls) Width: 20' exterior to exterior, or 18' 8'' interior to interior The division: The idea is to have a comfortable size control room, while keeping enough floor space for a live room and a small vocal booth. Circulation between the spaces would be by the airlock provided by the stairwell adjacent to the new structure. Sound levels are expected to be around 85 dB SPL in the control room, and as much as 115 dB (is this realistic, for a full band?) for the live studio. The insulation: Like mentioned above, the need for good insulation between the first and second floor is very real. We need to be able to track a full band downstairs while maintaining a relatively quiet space upstairs. Proximity to the road is also an issue, the building being located on the side of the main road. Sound proofing between the built extension and the existing building should not be a problem because of the stairwell acting as a spacer between the two. I was also considering the idea of using this space (the stairwell) as the airlock between the studio and the control room, thus leaving the entire space available. Keep in mind that the build has not yet started, so the plans can still be tweaked to add a door here, scrap a window there, etc. Here is the general idea I had concerning sound proofing, along with technical data for all surfaces: Floor: Heated 4'' slab on Grade From the info I've gathered around, I understand there is no need to treat the floor for insulation between the rooms because of the dampening effect of the earth on which it rests, correct? Exterior Walls: The first 5' of the exterior walls (foundation walls) are 8'' thick reinforced concrete. The remaining are typical exterior walls that comply with the thermal and hydric insulation needs for this part of the world. To save interior space, I was thinking of using the exterior wall as the second leaf of my 2-leaf structure, beefing it up to approx. match the STC of the foundation wall on which it rests. Interior Walls: Interior walls would then essentially be the first leaf of my 2-leaf structure: 2'' 1/2 Metal Studs @ 24'' C/C with 2'' Roxul wool and 5/8'' gypsum boards (how many is still to be derived from the needs in soundproofing). I plan on leaving a 4'' airspace between the two leafs, leaving space to run the snakes and other wiring. Ceiling: Resilient channels (Z channels) on support beams with 3-4 gypsum boards attached to them. No connection between ceiling and walls. Roxul wool in the cavity above the gypsum. ***All joints, cracks and corners are to be sealed with acoustical scellant. All walls to be resting of Neoprene pads 1/4'' thick. The acoustics: Control Room: I've mainly focused my work on the acoustics of the control room so far, because achieving optimal characteristics in this room will dictate the space remaining for the studio and booth. I've read pretty much everything that was to be said about room modes and optimum room ratios, but I'm still faced with this problem: Considering the fact that it is impossible for me to satisfy to the optimum room ratio because of the height of the room (13' 10''), would it be best to reduce this height or keep it as it is and add more bass trapping? My gut tells me that a higher ceiling would overall give a more interesting quality to the acoustics of the room... maybe i'm wrong. The hand-drawn draft I have attached to this post is a design that is consistent with this thinking (higher ceiling, more bass trapping). The dimensions in the draft are as follows: H: 13' 4'' L: 17' W: 15' 6'' Semi-circular areas noted ''D'' are specular diffusors mounted on resonators tuned to problematic frequencies. Triangular areas noted H.R. are Helmholtz resonators tuned to problematic frequencies. Apart from these resonators, bass trapping is assured by hanging panels with rockwool (as seen in other designs). Question: "How do we compute the technical specifications needed for the design of these hanging panels?" Is it as simple as "depth of the cavity = 1/4 desired absorption wavelength" or do we have to also take into consideration the spacing between the panels? The modal distribution with these dimensions is not ideal, but I remember John saying somewhere he had never took modes into consideration for his designs and people who have worked with him seem quite happy nevertheless! I am not sure whether I should worry about this too much as I do now... I have upload also another design idea I had, which is not to scale. I have decided to go back to the straight walls/angled treatment design (hand drawn draft) for the ease of construction and computation. Maybe with you guy's assistance I could manage a satisfactory result using the splayed walls for the control room... To conclude this first post: - Are there any major flaws in my thinking so far? - Do you have suggestions regarding the layout and design of this studio? Thanks in advance to everyone that will take the time to read this long post, and hopefully your knowledge and wisdom will guide me in the path to better design. Alexis PS. I have not yet computed the info for the live studio and the booth because I am waiting to have the final measurements for my CR.

welcome! couple of thoughts: 1) the slab (if possible) should be separated between rooms and the walls for the best isolation; 2) the ceiling in the CR can be 11' high and the live room 12' and thus leave enough space for the HVAC and avoid tying the ceiling to the upper supports. support the ceilings on the inner isolation walls each on its own slab. you will need air. so do not skimp on the HVAC design. to ensure proper isolation you want those duct decouple and the ceiling/wall penetrations to preserve the isolation and avoid transferring sound between rooms. I don't see any isolation booths in the design but presumably you'll want a pair of those on the far end of the live room facing the CR and with wide glass doors you can open when you don't need them as isolation booths. for the CR, all the usual suspects for treatments to get the flat response with the right RT60. i'd probably go with a bigger window in the CR. for the live room consider reversible or changeable treatments to allow the room sound to vary. having the stairwell as an air lock might not be best unless their is an intermediate door because the sound will escape into that space when you open the doors (either room) and therefore into the upper stairwell space where it is most likely not wanted. maybe this means encasing the bottom area of the stairwell and putting a door there.

Wow... experience has spoken! First of all thank you for this quick reply. I have often benefited from your interventions on other's topics so i'm glad to have you as a first replier.

1) the slab (if possible) should be separated between rooms and the walls for the best isolation

Gotcha.

2) the ceiling in the CR can be 11' high and the live room 12' and thus leave enough space for the HVAC and avoid tying the ceiling to the upper supports.

Can't believe I forgot space for the HVAC! I was saving it for later thinking the design had to follow the layout of the floor plan... lesson learned, thanks.

I don't see any isolation booths in the design but presumably you'll want a pair of those on the far end of the live room facing the CR and with wide glass doors you can open when you don't need them as isolation booths.

The design I have uploaded was only for the CR. I had planned on 1 iso booth at one corner of the live studio. Do you think I can manage two of those without sacrificing the liveliness of the studio?

for the CR, all the usual suspects for treatments to get the flat response with the right RT60.

What do you mean by usual suspects? :horse:

i'd probably go with a bigger window in the CR.

I was trying to cut on costs there, maybe I should stand my ground and make a point about the importance of visual communication between the spaces.

for the live room consider reversible or changeable treatments to allow the room sound to vary.

Yes! I already started to design panels that open for absorption and close for diffusion. I'll post them here once i'm done.

having the stairwell as an air lock might not be best unless their is an intermediate door because the sound will escape into that space when you open the doors

Access to the upper floor and to the existing building is separated by a door. I was thinking that absorption on the ceiling and walls of the stairwell, coupled with these access doors would do the trick...? Thanks again for the reply, Glenn. Now back to the drawing board and I'll come back with a few more questions i'm sure! Until then, happy holidays!