Improving the accoustics for my basement theater

Discussion in 'Home Theater Projects' started by Dan Mages, Nov 17, 2005.

  1. Dan Mages

    Dan Mages Auditioning

    Nov 14, 2005
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    Greetings all!! I have been lurking around here for over a month and have seen a lots of awesome information about building home theater rooms. So much so, that I am lost on what to use for this project. Here is the lay of the land.

    My basement is right now bare concrete on the walls and the floor in the main living area, so anything goes. The ceiling height is roughly 7' 6". The house has a Futuresmart panel in the basement with full wiring throughout the house. This will be my source for the TV signal and possible audio broadcast throughout the house. Darn cool stuff if you ask me.

    The layout. The basement is approximately 24'x 15' As you walk into the basement, you will have the theater area in front of you. On the far wall is a 12' row of built in book cases on the right corner of the room. To the right of the entrance will be another smaller book case for my record collection (700ish records and growing). There is a 6ft wide by 30 inch tall window on the right side. The left side of the basement will be my pub area with a bar on the inside wall and a game area in the remaining area. There is a 36" exterior door on this side. I am quite handy with tools, and will be doing the work myself.

    Equipment list. I currently have a Denon 3805 receiver, a Harmon Kardon HK720 turntable, and JM Lab's Sib and Cub speaker set up. I am considering a front projection system, but I am not sure if the room is big enough to make use of it. I figure there will be 10 ft between the screen and the viewing area.

    My goal for this project is to improve the accoustics in the room. Any advice on how I can improve the accoustics in this room is greatly appreciated. with three exterior walls and one facing a storage closet and the utility room, sound isolation is not a major concern.

    Thanks for any help that you can provide on this project!!!!

  2. chris_everett

    chris_everett Second Unit

    Jul 20, 2003
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    First and foremost, remember that accoustics is still more art than science. Take _everyones_ advice, including mine, with a large grain of salt.

    There are three sorts of accoustic treatment to concern ourselves with.

    1. Absorption
    Absorption, as it's name implies, is used to absorb sound rather than have it reflecting around the room. Lots of things absorb sound, from carpet, to soft furniture, to people, to foam absorbers designed for that purpose. In my theater I used foam absorbtion on the ceiling, and a strip around the room at ear level. With concrete walls, you will want lots of additional absorption. You can also build your own absorbers with a specialized fiberglass and some fabric.
    (Google for instructions)

    2. Diffusion
    Diffusion is used to reflect sound around a room randomly, rather than in a consistent direction. Although there are "diffusers" you can buy, many home theaters have plenty of natural deffusion with the detail work, trim, furniture, bookcases, DVD cases, etc. Spend your time/money on absorption

    3. Bass Trapping
    While Absoption and diffusion will keep a room from sounding like an echo chamber, the biggest accoustical choices involve bass trapping. All rooms have low frequency problems (usually lots of them) and they are usually severe, with lots of bass in one spot and none in another. The most important issue is the size of the room.

    First, download "modecalc" from

    This little DOS program will show you your problem frequncies for a room of a given size. If you have a lot of problems at one frequency, you may want to shrink your space a bit to help. It will also give you an idea of what your problems will be.

    That should get your started, let us know how things go.

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