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Discussion Starter · #1 ·
I have been reading a lot about room treatments lately, so much so that I can't help but think that my theater is treatment deprived. I have a dedicated room. about 14x22x8. The ceiling has wood soffits made from pine and the the rest is a dropped ceiling with acoustic tiles. The walls are double sheetrocked with batting on the top half, acoustic panels on the bottom covered by GOM. Two windows on the left side of the room are covered with a frame wrapped in batting. Any suggestions on panels, other things that may make my theater better. Not that it sounds bad now, but I can't help but think that improvements can't be made. I like to go the DIY route when possible(limited budget). Any ideas.
 

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Once can always make improvements. However, it hardly sounds like the room is deprived, maybe just misguided ;) It sounds to me like every surface is covered in some sort of absorbtion as it is now!


I would take some measurements of the room response and do some RT60 calcs to get a handle on what the room is really doing. I have no idea based on "acoustic panels on the lower wall" and "batting" on everything else but the soffits.


Do yourself a favor, do the measurements and the calulations and see where you stand FIRST before adding any more absorbtion.


The only thing that appears to be "missing" is some absorbtion at the reflection points and more on the front wall (and potentially some dedicated bass traps.) What and where it is needed will come from the measurements.
 

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Since I'm rebuilding my Theater to do it right, my designer asked what I thought about using some Sound Systems Acoustical Wall coverings to finish everything off, if I decide to skip AI and go with the DIY treatment, still getting the look i'm going for. It's made by Technique Textiles, it's a carpet look and feel. They use it in factory office's to kill the sounds from outside the office. I'm wondering what it would do for a Home Theater. I went to see a room with it installed and the room was dead quiet, no echo at all.
 

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Discussion Starter · #5 ·
Thanks guys. What do I need to make measurments? Is there some kind of device or tool?


Ethan, I will take a look at those articles, thanks. I think I understand some of the basics, butit seems everyone lately is making panels and traps and all sorts of things. A couple of years ago everyone was just doing the batting on top half or walls and some sound board up front and bottom half of walls, so thats what I did.
 

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Discussion Starter · #6 ·
Alright, lets take another approach with this. My plan is to start redesigning my theater and I think I am going to start with the front wall. I have enclosed my current front wall layout. With the all the speakers it is too busy, I want a nice clean look.


So I plan on building a false wall in front out of 2x4's and covering with fabric. The speakers will sit in the 2x4 wall so they will all look flush from the room. Now what is the best treatment for the front wall. I currently have ceiling tiles glued to the front wall, should i try something else instead? I am not concerned about covering them as the false wall will cover everything. Should I use some of these 702 0r 702 panels I keep reading about? If so how think and can I just attach them over the ceiling tiles already on the walls or should i remove them(may be hard as they are glued)?
 

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Hi Mark,


Hiding speakers behind a false wall of fabric is an excellent strategy. You should be able to leave the ceiling tiles, and cover the wall with a 1-2" thickness of any brand of fiberglass with a 3 pcf density. This will treat early reflections from the screen wall and in general improve the accuracy of sound in your theater. Disclaimer: without an analysis, it's very hard to do accurate room diagnosis and treatment recommendations.


Treatment of other walls and/or addition of bass absorption behind the false wall may be necessary. However your acoustic tile drop ceiling may already provide sufficient wideband absorption. Such ceiling structures vary greatly in their effectiveness. The only way to know for sure is with an acoustical analysis which includes measurement of reverberation times and early reflections.


Regards,

Terry
 

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I agree with Terry. You probably already have much of the spectrum covered. I'd hit the reflection points on the side walls and maybe a little fiberglass behind each speaker and in the center between them and then measure the room.


You might still need some low frequency absorbtion but like Terry said, it's a real crap shoot until you actually measure it. You can take some educated guesses based on dimensions and furnishings. HOW you trap the bass if needed is going to be guided somewhat by what the rest of the absorbtion is already doing.
 

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Quote:
Originally posted by marjen
TWhat do I need to make measurments? Is there some kind of device or tool?
I (and others) recommend ETF, from www.acoustisoft.com. You will, in addition, need a quality microphone and preamp for your PC. This will set you back in the low hundreds of dollars.


Or for a roughly comparable price (since you are near Rhode Island), we could come out and do an analysis :). Advantage: professional analysis by an experienced acoustician. Disadvantage: one time, vs. ETF to use as many times as you like.


Regards,

Terry
 

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Discussion Starter · #10 ·
OK, So fiberglass up front, should I cover all surfaces behind the false wall with fiberglass? Such as the front wall and the small portion of side wall and ceiling? Now how thick? 1" 2"? ICan you get this 701 and 703 stuff at home depot? Or do I need to special order it?


The side walls are what worry me most. I have posters (2 on each wall) along the walls and I am concerned they may cause some reflections.
 

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I understood that you already had the real front wall covered in tiles. If so, you really only want/need additional absorbtion (wider band) at the reflection points as I stated.


1" 703 or equivalent spaced out from the wall an inch or 2 will do fine.


Posters (even in a glass frame) aren't going to reflect any more than the drywall under them. Even with absorbant already on the wall behind it, the amount that the poster takes up in relation to the whole wall is trivial. The only issue would be if they were located at the side wall reflection points.


You might consider hitting the ceiling reflection points if you want.


HD does not carry 703. Other brands are available - not just Owens Corning. You are looking for a 3lb/cu ft. rigid fiberglass. The thicker the material, the lower the frequency it will absorb. You can order it but shipping is not cheap due to size. IF you only need say 5 panels, it wouldn't be too bad as long as someone would sell it to you that way.
 

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Discussion Starter · #12 ·
Here is a very detailed drawing showing the room size, location of speakers, subs, risers, windows and seating. Looking to see if anyone can see any problem areas. Thanks.


The thing I see is maybe the location of my first row seating, it is JUST past the 1/2 point in the room.

 

theater 2004.pdf 27.4609375k . file
 

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Unfortunately, it looks like the poster and window (depending on height) are not in good places. I'd bet you that the'll be issues with the first reflection points. If you are serious about doing this, I'd consider maybe moving the poster.


The seating is still close enough 10 1/2 that you may have null issues in the bass and the even harmonics. Not sure what can be done though. Depending on screen size, you're already @ 8'. Wouldn't go much closer probably. Farther back looks like an issue to potentially.
 

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Discussion Starter · #14 ·
Well I know the seating situation is tough. I have the riser built. Unfortunately when I build the theater I did not take that into consideration. I did decide to build a stage instead of a false wall. It turned out to be the least destructive to the existing theater layout. Looking at getting fibergalss insultion. Found one place that carries it, hope to pick it up at the end of the week. Here is pic of the new stage framed out.
 

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Go spend $40 at Radio Shack for a meter, $5 for a cable, download the free version of ETF5, install it on your PC and go for it. Total cost; $45 plus your time.
 

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Discussion Starter · #18 ·
Actually I have the Radio Shack meter already, I use it for calibration. I take it this software is NOT available for mac? Actually I think I could track down a PC somewhere. What type of cable do I need?
 

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Quote:
Originally posted by bpape
Go spend $40 at Radio Shack for a meter, $5 for a cable, download the free version of ETF5, install it on your PC and go for it. Total cost; $45 plus your time.
Bpape,


[Edit]....I started a "ETF for Dummies" thread [end edit]......, can you (and perhaps Terry or anyone else familiar with it) walk us through using it? When I say walk, I may actually mean crawl :)


It seems like it is a great tool, but not the most intutive for people non-accustomed to it. For example, what am I suppose to use when measuring RT60?? Should I be playing pink noise (from one or all speakers), a sinwave? How and what should you use to calibrate the mic (in my case a RS SPL)? Yes there are some basic instructions, but they were not very clear....but perhaps it's just me.


I think it would be helpful to many of us.


-Jason
 

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Quote:
Originally posted by marjen
Actually I have the Radio Shack meter already, I use it for calibration. I take it this software is NOT available for mac? Actually I think I could track down a PC somewhere. What type of cable do I need?
My RS SPL meter (analog) required a RCA to 1/8" plug adapter --->$4.29 at Radio Shack ( part# 42-2444 ).



-Jason
 
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