[philiprst]

I am looking for some guidance on the design and construction of a small home theater in our basement. I have spent the past couple of weeks reading and searching in this forum and feel a lot more educated than before. However I am still a little confused about some of the acoustic issues I need to pay attention to. so I thought that I would list some of my questions and ideas and hope that someone here will be kind enough to answer.


BACKGROUND: The home theater space will consist of a dedicated room in the basement and will be constructed as a part of a larger remodelling project. At the moment the basement is just an unfinished just big open space. The only existing wall that will be part of the finished room is a 2x4 exterior stud wall insulated with R11-R13 fiber. At the moment this wall has not been drywalled. The distance between the concrete floor and the 2x10 ceiling joists is 7' 9".


QUESTIONS:


ROOM DIMENSIONS: The dimensions of the finished room will very restricted. The length must be

 

[tlllava]

Philip,


Good questions that are asked about once a week. Here are some good threads:


Insulation:
http://www.avsforum.com/avs-vb/showt...hreadid=352519


Room Dimensions:
http://www.avsforum.com/avs-vb/showt...hreadid=353205


Wall Treatment: Short answer, it can only make your room sound better. Search for insulshield.


Soffits: Search for that term for many links.


Where are you in Maryland? Perhaps we can get together & trade ideas. I'm in Elkridge.


-Tom

 

[schmidtwi]

Another good idea is to follow the links to completed HT's to see their construction photos and comments from the generous individuals that love sharing their experiences. Or hire someone to help with your design.

 

[Ethan Winer]

Philip,


> Studying the room modes suggests the there is little I can do to make the room dimensions anywhere close to ideal; not without reducing the square footage dramatically, anyway.

 

[Michael Green]

I've heard some great small rooms. Remember it's how you build the room thats important. I was working on a room for the London symphony six years ago. The room was 11 by 12, we were using 5" woofers and getting a linear response to 38hz with only one little peak at 3500hz. Little rooms can do some amazing things.


good luck

 

[krasmuzik]

Wow - big welcome to Michael Green...


Just when you thought this forum could not get more interesting.....now we should have some really interesting acoustics discussions!


Philip your concern with footfall noise means you need to research ceiling/floor system not based on STC (sound transmission coefficient) but instead look at the number for impact isolation. IIC? - I forget the acronym.

Normally home theater concern is about not letting sound out - and not so much somebody tapping on the walls!

 

[bpape]

In a small room like that, you may find that diffusion might be of more benefit than too much absorbtion. Hit the high points with absorbtion, add some diffusion on the back wall and some decent bass trapping and you should be OK.


I'll defer to Michael and Terry as they are the real pros here. I can only describe what has worked well for me in the past.

 

[Michael Green]

Hi guys,


1. Be careful of soffits in short rooms.


2. Once fabric is added to a room you have lock yourself into a particular sonic flavor that heads to-wards killing the sound. You want to control the sound not kill it. I'm not saying don't use fabric, I'm saying use it wisely. [ carpet and stuffed furniture is fabric ]


3. Before putting in floor covering lay down a layer of wood. By doing so you will gain better tonal balance. Use the same wood on your riser.


Questions


1. How big are you planing to make your riser?


2. Where is your door?


3. What is your speaker configuration and placement?


4. What type of floor covering are you planing on using?


Note


Remember your room is going to sound like the products and materials used to build it. I've seen alot of people use the wrong combinations, then be stuck with trying to fix it.


Theory is great, reality is better.

 

[Dennis Erskine]

Just a nitty point...fabric is not a treatment. What lies behind the fabric is what counts. Thus, if you're looking at pretty pictures, understand the fabric you're seeing may have different 'stuff' lurking below. Don't assume that just because you see fabric everywhere, that fiberglass is behind it all. It could be fiberglass, diffusors, resonators, absorbers...any number of things.

 

[Michael Green]

Hi Dennis,


Hope your doing well. We do a lot of testing on different fabrics mostly listening test. We have found that fabric makes a big effect on the sound. There are many acoustical fabric companies out there.


It's important to find a synergistic blend of all the materials being used, as I said in my previous post.


have a good day

 

[JimBookhard]

Quote:

Just a nitty point...fabric is not a treatment. What lies behind the fabric is what counts.

Although what you say has merit, fabric does and can make a considerable contribution as to what the sound will be, otherwise not so many speaker manufacturers (or reviewers) would recommend removing the fabric grill covers on loudspeakers for best sound performance.


Just a thought.

 

[Dennis Erskine]

We've tested considerable fabrics here. The point being that someone installing thin fabric on the wall and expecting audible differences in reverberation time or reflections will be sadly disappointed. Clearly the use of a very heavy fabric, or heavy curtains, will have a high frequency impact of varying degrees.


Jim...it disappoints me when speaker manufacturers make such statements. Either they are saying they cannot compensate for the fabric or they couldn't use a good acoustically transparent fabric, or they are suggesting their grills are horrible works of art and shouldn't have been included with the speaker in the first place. Rather like buying a Bently and being told to take the burled walnut out to improve performance. If that's the case, why is it there in the first place. You might ask the speaker manufacturer some serious questions about their published response curves...measured with or without the grills...and if the grills ruin their speakers, why'd they include them in the first place? Just to put expensive bad sounding speakers in listening rooms?

 

[Ethan Winer]

Jim,


> otherwise not so many speaker manufacturers (or reviewers) would recommend removing the fabric grill covers on loudspeakers