Tell me the weak points of my vocal/iso booth idea

Im building a vocal/iso booth. I'd like to know the flaws/weakness of my idea. The booth will be exclusively used for vocal and guitar cabinet tracking. Im going to do a wall inside a wall design. I plan on doing a 4'Wx5'Lx7'H (interior dimensions) booth. For the exterior walls, Im going to use 2 layers of 5/8" drywall mounted to 2x4 studs. The interior walls would be 4"OC 703, wrapped in fabric, placed between 2x4 studs. For a door, I'd use a thick, solid core door, with a 2"thick OC 703 panel wrapped in fabric, mounted to the interior of the door, to cancel some reflection. The ceiling would be made using 4" OC as well, with either sheet rock or 3/4" plywood for the exterior. I cant afford a super high quality door sealing system, like those on Acoustic Solutions, So I'll be using Neoprene gaskets, spring loaded hinges and a commercial door closure to keep a tight seal. I'll also be installing a small double paned, angled window. Probably 2'x2'. I wanted to know your thoughts on the using fabric on the interior to cover the 703, rather than using drywall on the interior. I just assume that covering the 703 with drywall would reduce the amount of absorption (and/or increase reflection). Also, what are the pros/cons of using plexiglass rather than glass for the window? Lastly, is it necessary to use slot absorbers on the interior walls? If so, on how many walls? and what size slots? I tried using one of the calculators on this site and I swear I could hear my brain cells sizzling. Thanks

Aloha, If I understand the description correctly, the design uses a single leaf (albeit double layer) construction. While this might produce acceptable results for vocals, depending on your isolation requirements, a loud half stack may prove otherwise. Check out the the diagram attached and note the illustration/construction at the far right. This would be described as a two-leaf system (good). What you do want to avoid is a thee-leaf system (bad). If you were to use John's inside-out wall design http://www.saecollege.de/reference_material/index.html (click on construction tab, then walls & ceilings tab) in addition to the STC 63 construction, you may have a viable solution. Because John's inside-out wall design does not entirely enclose the layer of insulation it then avoids the problems of a three-leaf system. I seem to remember a thread or two discussing the plexi-glass/glass debate with the "mass of glass" being the material of choice. Perhaps using the search function might prove fruitful.

is it necessary to use slot absorbers on the interior walls? If so, on how many walls? and what size slots?

Necessary? That depends on how "dead" you want the booth to sound. The slat help to keep a bit of the highs "live." Some of John's designs have used slats on two of the 4 walls. Hope this helps, Aloha 8)

Thanks for the response! Before you even responded I found the answer to my Plexi vs. Glass question, and clearly glass is the way to go. no pun intended. I took all of your info into consideration. The main problem with this project is space. obviously a double leaf plan would be the best, but due to space im not sure if i can make it work. Since my main objectives are recording vocals and guitar amps, that sound great while at the same time doesnt get me evicted from my apartment, I wanted to know if you think using a single leaf wall (2ply 5/8" Drywall, 4" OC 703 wrapped in fabric) would be enough to isolate the vocals, and then to deal with the guitar situation, I could construct an Iso Cabinet, which would be placed inside the vocal booth.

Aloha, Hard to say without knowing what your isolation requirements are. Perhaps an investment in a Radio Shack sound level meter http://www.radioshack.com/sm-digital-di ... 03667.html would be a good place to start to get an idea of what you need isolation-wise. Aloha 8)