control room shape

Hello John! Hello all ! It may be a stupid question, but i am seriously asking myself this one. You have a rectangular sized building and you want to build a control room inside, should you build your internal walls (isolation vs outside world) following the building shape and then give the room the octogone or hexagone shape only with the internal treatment walls ? Or should you build the room with the shape you want (octogone or hexagone) to force the sound following the path you want and then treat the inside the best you can with the room left???? Same question goes for the ceiling, splayed or not ? Have a look at the design i made and please give me your advice Philippe

Bump !!

I'll take a shot at this. there are a couple of approaches as you've described - one is create an isolated room with good modes and build inside a control room based on treatments, or, create a room (based on approximations of good modes) with angled walls and treatments as needed. depending on the space you have available, construction experience, and isolation requirements, you can go with either design model. if you have an open space, I would tend to go with angled walls in the design, and obviously if you have a small space or its primarily a rectilinear space, you're pretty much forced into dividing up the space for practical purposes and apply treatments. From a ceiling perspective, I've seen arguments for high front - slope down behind mix - then slope high back, and other cases for slope up front, even higher slope mid, and slope down back, or a consistent slope upwards from front to back. each design seems to have merit when the rationale behind it explained by someone with an heavy duty engineering degree... my preference would be to slope up front to some point behind the mix position and slope down using the ceiling to hide additional treatments. surface of the ceiling to be defined by the level of brightness desired in the room with the idea on keep reverberation on the low side. in the case of your design, I'm assuming the slope down towards the back is to enable more treatments overhead (past the rear speakers). if need be, you could add a cloud overhead to reduce reflections on the mix position and trap reflections that might occur between the front and rear speaker sets. the side wall positions that are parallel are a possible source of flutter echos so some moderate absorption there would probably be useful. if this is built in a rectangular room, the areas behind the front angled walls and the rear corners can be used for additional trapping. one thing I've seen is the rear speakers in sidewall soffits which also house trapping. this would breakup the flatness of the sidewalls.

Glenn, thank you for your answer From what i see, you would preferably go for a design with angled walls but this arises the problem of room for treatment (especially in the low end) Speaking of ceiling, its not clear in my mind that if you have a sloped one and you use the slope for treatment- but if you do that you end up with a flat ceiling !!!! i don't get the point here Thank you for clearing things in my confused mind Philippe

Bump !

in these examples, you see the false ceiling (hopefully) and above it the hangers (illustration only, in reality you'd have bunch of different sizes, positions etc...). the sloped ceiling not only hides the hangers but also other treatments you might have in the space and may be constructed to reflect more or less depending on liveness desired. I've seen some rooms where the false ceiling was sheet metal... very live... the top ceiling of the structure is what you use for your design measurements in determining room modes, and the false ceiling construct is the treatment. ideally if you can define the actual structure, you can build it so its not flat, and in combination with the treatments is even nicer. in a purely angled wall design, you either need to make or find pockets to build in the trapping, or find other ways to treat it. in the end design is about finding acceptable compromises unless you have unlimited budget, time, and/or opportunity...

Thank you Glenn i think i begin to understand better. To be perfectly clear: - angled walls and sloped ceiling are better in respect of controlling the sound reflections - try to create pockets and places to hide the treatment in this structure Am i right here ? another question (if i may): how do you calculate the amount of absorption (in sabines) of hangers bass-trap system ? thank you for helping Philippe

generally speaking, estimate based the the absorption on the material wrapping the hangers, any ceiling/wall treatment above the ceiling (for instance if you lined it with mineral wool or similar), and if you put a layer of 1" (25mm) 703 (or equiv) on the cloth-over-plastic false ceiling + the air gap (averaged). you can use this with the surface areas to calculate the estimated RT60. the fiberboard/soft ply used in the hangers should be included, so you can add in the area of that as well when looking for an overall number.