I have been researching various design/construction techniques for building a 'room-inside-a-room' home theater / stereo listening room and have several questions about creating a soundproof enclosure. Below is a description of the space where I intend to build the enclosure and a summary of how I propose to build the walls/ceiling, followed by my questions. I know its long with alot of questions, just feel free to answer on any topic you know about. THE SPACE: I want to build the soundproof enclosure in the basement of a house. The Basement is totally unfinished (except for the wood stairway leading down to it from the kitchen). The floor of the basement is the concrete foundation of the house. The basement area provides several expansive open spaces which provide ideal locations for constructing a home theater / listening room. The largest unobstructed section of the basement spans 30' x 20', with two sides of the space being the side walls of the house's foundation. ENCLOSURE DESIGN: I want to take some time and seriously research design/construction methods recommended for such an enclosure before I do anything. My primary goal is to build an enclosure that isolates the sound inside the enclosure, so I can play full volume, without excessive sound escaping to the rest of the house. My secondary goal is to to engineer the room for acoustic accuracy. My last goal is to make it comfortable, but I am quick to sacrifice any comfort/aesthetics to acheive my first two goals. I intend to do as much as possible on my own, not only to save money, but because I think I will gain something from the process of designing and constructing it myself. My idea is to build a completley free-standing enclosure 25' x 15' in the 30' x 20' basement space. I intend to locate the enclosure 3' from each side wall of the house's foundation, so it will be a totally free-standing structure, with a seperate ceiling. Everything I have read about isolating sound from a home theater room emphasizes the need to eliminate/reduce vibrations transmitted to the rest of the house through the joints/ceiling/walls/etc... I am hoping to eliminate vibrations transmitted to the rest of the house altogether by completely isolating the enclosure from the house, with the only contact of the enclosure and the house being the house's foundation (which I hope will not resonate much or transmit too much sound). My theory is, by seperating the physical structure of the enclosure from any contact with the house structure, I should be able to almost completely isolote the sound from the rest of the house. SOUND PROOF WALLS: I am currently searching for the ultimate soundproof wall design. I am imagining building a standard frame with 2x6's, then fill the space in between the 2x6's with standard fiber glass insulation and attach two layers of sheetrock to both the interior and exterier of the frame. Finally, I will line the interior of the listening room with 4" convoluted acoustic foam (expensive, but from what I read, nothing quite works like the real stuff...?). I hope this design will provide enough matter of varying density to disrupt most of the sound produced in the room, and prevent much of the sound from leaking out of the enclosure. In my search for the right sound proof wall design, I came accross the ASC website (excellent!) and read about their 'walldamp' and 'iso-wall' products/systems. http://www.asc-soundproof.com/ If I understand these materials/techniques correctly, they are intended to provide a physical vibration barrier in between the listening room and its physical connection to the house's frame. I don't think this applies to my proposed design because the whole point of isolating the entire listening room enclosure in the basement, independent from the house's frame (other than contact with the house's foundation) is to eliminate contact with the house's frame altogether, thus eliminating the possibility for sound to transfer throughout the house. (if I understand this...?) SOUND PROOF CEILING: I imagine using the same 2x6 frame I described for the walls of the enclosure to create a ceiling. I would then install a traditional hanging ceiling to the interior of the listening room enclosure. SOUND PROOF FLOOR: Since the floor is the solid concrete foundation of the house, I was not planning on constructing any floor for the enclosure. I would only lay down some heavy carpet to provide dampening inside of the listening room (mistake?). SOUND PROOF ENTRANCE: I imagine using a standard wooden door (maybe steel?) and insulating it with acoustic foam and sealing it with a foam-rubber seal. I saw a steel coated door at home depot that came in a frame already sealed with a rubber seal for under $100. (Will this work?) QUESTIONS: 1) Am I correct in thinking that building a seperate enclosure will completely isolate the sound from the rest of the house? 2) Is there a risk that the enclosure itself may viabrate/resonate, potentially causing sound to travel throughout the house anyway? (this would justify application of the ASC soundproofing materials/techniques to eliminate viabrations...?) 3) Will longer wavelengths (low-frequencies) pass through my proposed soundproof wall/ceiling? If so, can I trap the low frequencies and keep them contained in the listening room somehow? I will most likely employ tube traps (from ASC web site...) inside the listening room. I thought these may partially help to quiet the the room as well as provide better bass response inside of the room. 4) I am proposing multiple layers of drywall and insulation, with the interior of the room covered in accoustic foam as the primary sound barrier. Are there other matierials that I should be considering for the soundproof walls/ceiling/room interior? I have seen mention of others using Z-shaped material for creating soundproof walls on other threads, and I have heard there are other materials designed specifically to block sound. 5) An article on the ASC site mentioned that if you are building a listening room, you should consider 'building-in' accoustical enhancements into the room as you construct it. An example was given of someone who built in a low-frequency baffle into their listening room floor to improve the low-frequency accoustics of the room. Are there any simple enhancements I may be overlooking that could readily incorporated into the construction of this room to improve the acoustics? 6) Any good references (books/websites/articles) to learn more about designing/constructing a professional listening room at home, or on listening room acoustics is greatly appreciated! Thanks for any insights!