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Eric,Here are some acoustic treatments I did recently.I used Roxul brand mineral wool because I was not able to obtain the OC 703 fibreglass.

The tall blue panels are for first reflection points on the side walls ,the small panels with pine frame are to tame reflections on the rear wall and the big white traps are placed behind my main speakers.
 

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Wayne,

> just how much 703 treatment does a room need to accomplish this? If it’s as many square ft. as the carpet on the floor, that’s an awful lot of wall treatment! <

Again, the issue I was addressing is not so much the total surface coverage as ensuring that whatever absorption you have is sufficiently thick to absorb to low frequencies as well as mid and high frequencies.

Even though small rooms don't really have "reverb" per se, RT60 measurements are still used, and they work well enough to assess the decay time. This is the part you're talking about. Most listening rooms do well with an RT60 of around 200 to 600 milliseconds. I prefer shorter decay times but others prefer longer. This is what changes based on the total surface coverage.

Now here's the part I'm talking about: RT60 is not a single number. Or at least it shouldn't be. The "correct" way to assess a room's RT60 is to look at the decay time in all third octave bands. It's one thing to have an RT60 of, say, 300 milliseconds at 1 KHz, but it's not so good if the RT60 is wildly different at other frequency bands. Using a thicker absorber extends the absorption to lower frequencies, making the RT60 more uniform.

--Ethan
 

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Thanks, Ethan. So I guess the simple answer to my questions would be “Use enough to get your RT60 down to between 200-600 ms.”
Exactly. :clap:

Both my home studio and my living room home theater have been works in progress for a few years. I'm happy now with both, but over time as I learned more about acoustics and treatment, and learned what to listen for, I added more traps and other panels and changed the placement of some. Of course, today I could do it it perfectly on the first pass! :bigsmile:

--Ethan
 

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I love this thread.. there is a lot of great info here.

First, to clarify, and I hope Ethan (or, of course, anyone else) will correct me if I'm wrong, the numbers in bold represent the sound frequency in Hz and the numbers below are the absorption numbers for the various materials I referenced. The readings are in Sabins (see here for a treatise). I've always read the numbers as how much sound is absorbed at a given frequency. Some numbers exceed 1.00, and you'll have to read the article referenced above for more info on that -- my brain started to hurt while reading it.

The RT60 is something I didn't really know about -- that will be something for future JCD to research. That being said, for those that know, is there a rule of thumb regarding treatment coverage to get to the right RT60? I've kind of worked on 30% as a rule of thumb.

JCD
 
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