Corridor as Airspace in M-A-M

Hi all, It's been quite a long time since my original project in 2003, a film sound mixing stage in a former theater that I own here in Los Angeles. I got a lot of help from many Sayers forum members, especially Knightfly, John & Rod, and now the time has come to tear it down and build a bigger one! In working on some preliminary drawings I've come up against a problem. The mixing stage will be built in the main room of the theater, which is 100' long and 45' wide (I know, pretty big). The stage itself will be a little over 50' long, and positioned roughly in the middle, front-to-back. Because of this (and other reasons), there needs to be corridors on either side of the stage to get from the front of the building to the rear w/o travelling through the stage itself. So here's my question; I'm already losing 5 feet on either side of the stage for the corridors. So that's 10' of interior stage width lost right off the bat. To build a typical M-A-M double wall system with 2 or 3 layers of d-wall on each outer face ends up with a wall assembly that's around 16' thick, and that's without any interior acoustic treatment. What I'm getting at is that I'm eating up the interior width of the stage like crazy. The existing exterior walls of the theater are 3 rows of brick, common for construction here in 1930. If I were to use the exterior wall as a MASS leaf, the corridor as the (giant) airspace, and then the "inner half" of the double wall system as the inner MASS leaf, how would that perform? I imagine I'd need to add some sort of skin (maybe fabric & pegboard or slats?) to the "corridor side" of the inner wall to protect the wall & insulation but not actually add enough mass to create a 3-leaf system.....Basically I'd end up with a M-A-M system that's about 6' 8" from one side to the other. Or, do I just have to suck it up and build the M-A-M assembly normally, but unfortunately 5' in from the exterior wall? Sorry for the long post out of left field, and I promise to post pictures this time! In the meantime, let me see if I can get a pic up of the existing stage. Best, Joe

Bumping up :) I guess the core question is whether or not a corridor can function as the air/spring space, or if I need to go ahead and build the outer side of the M-A-M wall assembly and take the hit of losing an additional 18" over the interior width of the stage. Thanks in advance!

74 views and no replies........anyone??? Thanks in advance! :)

I've wondered about this for a while myself. Logic says that a corridor is great "A" to have in your "M-A-M" design. I've always thought that the ideal studio floor plan would incorporate service areas like corridors & bathrooms to contribute to aesthetics utility, and isolation in a holistic way. But if this forum teaches anything, it's not to assume that what appears right, is right, without verifiable testing. I'd like to see an "official" answer from the people who design studios for a living and write books about it too.

Thanks for the reply Adam :) Yeah, I've tried to find the answer for "at what distance does a wall stop acting as a leaf (to avoid making a 2-leaf into a 3-leaf)", or conversely "at what distance does a wall stop acting as a leaf (thus making a 2-leaf into a 1-leaf)?" So far I've been unsuccessful in my search.

I'm going with YES. It will make your door seals and thickness even more important. but if your happy that the punters walking down the corridor will hear 10-15dB more in the corridor than the studios? Fine! In a way your building a small budget studio that can't afford the $$$. I'd like you to draw the alternate MAM (bullet biting senario) becuase in my hed i'm thinking that will be a 4 leaf system. Also is that a protools rig your running? lil

Hey Lil, thanks for the reply! Yeah, it's a bit of a weird scenario; spending the money isn't the issue as much as losing the space. Although I'm horrible with SketchUp I'll try to do an illustration of the 2 ideas, or (gulp) actually scan something hand-drawn, LOL. And yes, the gear you see in the picture is a 32-Fader Pro Control with an additional 8-Fader Main Unit for the odd occasion where I'm running 2 systems.

Joe - I'd do it like this. I'd make the inner walls inside/out construction. BTW - do you need 2 corridors to acces the front? whynot just one.

Hey John, thanks so much for that! The reason for the 2 corridors is two-fold; first, the seismic "kickers" are on both sides of the building, so 5' gets chopped off of each side. Over the length of the building the kickers "inch down" the wall; at either end they only go down 2 feet, but in the middle (where the stage would be) they extend 5' down the exterior wall so if unless I wanted to frame the stage walls around them, they would penetrate the stage walls. You're right, only one corridor is needed for front-to-rear access, but since I figured the space on the other side was going to be taken up anyway, on the other side the corridor doesn't go all the way, but ends about halfway, where I'll utilize the corridor space to increase the size of an iso room for music editors and such. So there'd be a door from the corridor to this space, and a door from the space into the rear of the stage. On the opposite side of the stage (where the full-length corridor is needed) there will be a smaller iso room for phonecalls It's clear I need to post a sketch, even I can't understand what I just wrote! Thanks again, sketch to come! cheers, Joe

OK, here's a scan of something drawn on graph paper, hopefully it will come through. At the bottom of the drawing is the full-length corridor, at the top is the half-corridor leading to the MX editor's room. Thanks!

"It's clear I need to post a sketch, even I can't understand what I just wrote!" :)