Mission Recording 3 room design, looking for finishing ideas

Hello fellow recordists and sound enthusiasts, I’m looking for some ideas on a small complex I’m building inside an existing warehouse space. I need to do bass traps. Do I need to do diffusion on the walls? As you can see from the drawings of the space, I am working with a small area, but I have good conditions and materials. All walls are 10' high, double 2x4 parallel, 16" on center with odd spaced ties, 1" apart. Rock wool was used in the walls. Ceilings are doubled 2x6 spans (16" on center) hung with joist hangers. Wall and ceiling surface membrane is ½" plywood screwed to 2x4's and glued with Sheetrock brand acoustic sealant. Second layer is ½" blackboard glued (carpet glue applied liberally) and nailed. Third layer is ½" sheetrock, glued and screwed through to the plywood. Fourth layer is 3/8" sheetrock, also glued and screwed through to the plywood. Each layer of sheetrock is taped for seal and no seams match except the corners (obviously.) Floor is concrete slab that was cut to shape of rooms for isolation. Floors are to be 5/16" pre-finished hardwood glued to 1/4" sheet rubber which is glued to the slab. Doors are custom studio doors manufactured by Krieger products, with an installed STC rating of 53 (talk about heavy and tight!) The space will have custom HVAC with large diameter flex ducting that originates at least 20' outside the complex, with a supply and a return for each space (2 supplies for the control and the machine room.) The machine room has a separate vent to the outside for drawing cool air in winter and to exhaust warm air in the summer. Electrical is stranded flex in an armored jacket with a 100 amp service and each outlet returning to an individual breaker with an isolated ground. The cable runs were made before the walls were built and each passes through the membrane ceiling above it’s permanent location. I am planning to hide the cabling in the absorption/diffusion. I also have power filtration and regulation for the computer and recording gear. I couldn’t do soffit mount speakers because of the design, so I settled for near field placement. If anything is confusing or unclear I’ll be glad to answer any questions. Here’s the beginning of the question session. . . How do I calculate room nodes (or are there any?) in rooms with non parallel walls? Can you recommend custom wall broadband absorption/diffusion that consumes as little space as possible? What are the recommended locations in this space? How do you do recommend window construction in a double wall space? How do you recommend constructing ceiling bass traps in the 1.5 feet of space around the flex duct? What kind of ceiling surface do you recommend in the control room? What kind of ceiling surface do you recommend in the studios? Since I have a very bright floor I was thinking absorption only . . . Should I do an HVAC return in the control room come down to the floor in the back corner and then bass trap around it? (Seems like that would cost a lot of space . . .) Any other ideas? Thanks for your input. missionrec

1st three pics Let me know what you need to see . . . . Thanks again! missionrec

Hi missionrec, It would be nice to keep those 10' ceilings, maybe clouds would do the trick and just paint the ceiling black. About the back wall defusion, looks like you have less than 10' behind your head, I know Knightfly reconmmended for me, just absorbtion if it's less than 10'. Anyone else have any ideas? You might try bumping this thread over to the construction forum and get more replies. John might also help with your walls and ceiling. Looks like you're headed in the right direction. Arthur

OK thanks Arthur. Also "newbie question" How do I bump to "Construction forum?" Do I copy text and start over? Thanks, hank

Hank - you need to read up a bit - go here and read up about abosorbers and what and why they work. ;) http://www.saecollege.de/reference_material/index.html cheers john

thanks, I'm there!

I would be worried about your door frames, seals, etc. Those metal frames appear to be shorting the two walls together. There don't appear to be any seal systems. What will you do for that?

The doors are bolted to the floor and each layer is sealed to the grout filling with Sheetrock brand acoustic sealant. Otherwise they are free standing . . . I'll try to get a picture up Monday. thanks for the insight! hank

The only big thing I can see is the 90 deg corner behind the mix position. Left untreated it'll reflect sound right back at the listening position. It's not too big of a deal to prevent though... Just make sure that there's absorption as wide as the speaker placement. Personally I'd build a soft absorber-wall out of 2x4s with rigid fiberglass in the stud spaces and fill the space behind it with hangers. You could make that corner an absorptive black hole if you wanted- just make the rest of the room reflective enough to get the live-ness you want.

Thanks dymaxian Is there any way to get a clue what the hyper active low frequencies will be before you build the trap? :? I like the soft absorber-wall idea but how do you design the hangers b4 you build the wall and how much space will this idea rob from the room? Thanks again for your interest. Hank