converted garage swinging doors

Hi all, my official 2nd ?post. sorry if I am premature in my questions. I will read up more if you think its needed. I started this thread http://www.johnlsayers.com/phpBB2/viewtopic.php?t=6773 about triple leaf and incorporating a 4x4 membrane panel trap on the inner wall of my swinging garage doors. It then changed to a absorber then a slot resonator. Then back to a BB absorber. After many appreciated replies, I want to repair the situation for better isolation and inner treatment. Attached pics are of the general layout, and current door scenario. I searched extensivley, but apparently not enough , or I could't find what I was looking for. My main concern is not totally isolation, but due to the information I gathered on the triple leaf phenomenom. I seek to incorporate building the garage door with acoustical treatment as the main ingredient. This garage is: 17x11.3x9' Built in 1920's true redwood heart timber. (the 4x6 is actually true 3x6), the other 2x's are current nominal studs I unknowingly added. It is used for a dual purpose i.e. tracking and mixing. Iam not too concerned about TL due to I don' have a full drum kit or full band coming in here any time soon :shock: Mostly jazz, latin and some light pop/rock genre stuff. At any rate I have a somewhat big dip(10dbs) @ 60, 100-140, 300& 400hz that I am trying to circumvent. The ceiling is 80 % soft, ultra touch R13 cotton insulation in the rafter cavity covered with fabric. Floor= concrete. Walls= stucco. sheathing, fluffy, 1/2" drywall with 2x4 studs. I have a 2x4 cloud over mix position and a 4x4 cloud in the rear. that is not in the 3d sketchup render. Now to the doors! I do think I need to seal the exterior better. But is there anything that could help, Its 4x8' x2 in size. The pic shows the constructin of the exterior and interior false wall. The inner door does have weather stripping . The 4x4 pnel is on the right side on inner wall. I looking for any ideas to possibly incorporate acoustical treatment into the door structure. Any opinions/ideas appreciated. Any lack of info, I will post pronto!! Tony

You are going to have to reduce the size of the pictures to something around 700 pixels wide before you'll get much help here. We have to keep scrolling left and right to read your post when the pictures are too big. You should also at a minimum, read the first post in this forum ("Don't even think about posting...") which discusses this. len

Thanks Len, upated the size. Hopefully it should work. T

No Bones? No hope?

Tonio, Wow, the othe thread you linked to certainanly took on a life of it's own :shock: Maybe could you take pics of the actual doors & rear wall and post them in this thread? Am I correct in trying to simplify your question(s)... You want a rear wall absorber to help take care of your dips (or maybe any absorber to take care of dips) AND you want to improve isolation of this rear wall assembly... BUT isolation is not as great concern as the sound with in room. Marc

Thanks Marc. I don't have the photo-genics in me, but I guess I could go out and buy or borrow one. Based on that thread I starting to think that because of the lack of isolation,its defeatinig the acoustical treatment. At least thats what i gather. Or with major isolation issues, the treatment doesn't effect where its designed to? I think you have it right. Bottom line is acoustic treatment, but I am willing to redo the whole inner false wall. Somehow there should be a way to incorporate the wall as the treatment without making a third leaf. T

Can you post a drawing of the ENTIRE door area, showing at least the entire existing door and your new proposed inner door? double doors are tricky at best, so more detail at wall/door junctions would help... Steve

Thanks Steve. Posted drawing of config so far and propsed build. Looking from top view. There is 2x's horizontally above & below the studs (cut view?) The bottom I have a MLV type limp under the floor 2x's for seal/moisture bearier & floating. The right exterior door I plan to permanentaly close/seal. And add in some sealing points to the left door. I added mass to the existing doors and prepped for 2 leaf system-or one leaf?. Biggest challenge bottom seal on the exterior doors!! The right door I can manage to seal it off, but the left??? Weatherstrip city I suppose? The inner and outter floor is concrete. The i/o junction does have a lip as a moisiture bearier. Would a slot resonator be viable on the interior where I marked fill and??? I'm looking at BB , not sure I want a narrow trap again. T

If multiple layers of panel have ZERO air space between them, they act as one LEAF but each LAYER maintains its own coincidence frequency unless you glue them together with ACTUAL GLUE - this is NOT recommended, separate coincidence frequencies makes the leaf stronger. Your drawings show some 3-leaf and some 1-leaf constructs, neither of which are good. The simple way to figure this is to pretend you are a SOUND - try to get through from one space (outside, for example) to another - optimum is if you must pass thru mass, then air (preferably with insulation in it) and then a second mass. More than that, or less than that, and you aren't at optimum isolation for the amount of material you used. If you want the best isolation you can get, don't put any sort of resonant trap on your outside walls - it will weaken isolation at its resonance (in addition to the already existing weakness at the wall's OWN resonance). Now, pretend you're a sound; try to pass thru each of your drawings, then re-draw what you think will work, and "Arnold" (as in, "I'll Be Baaack") :wink: Steve