Originally Posted by JMAX2016
So I've really been playing around with acoustic treatment over the past two months, moving them, stacking them (for lower freq absorption), and a loooot of listening. I have a 7.2.4 setup, with a 120" AT screen. Here's what I've learned, and maybe this will help in some kind of way.
1. Only absorb the whole front wall if you have an AT screen. Otherwise, I don't like the sound. I use 1" lin, plastic membrane, 1" lin (Thanks BIG!). I love the sound of this, because less SBIR (speaker boundary effect), great speaker localization, and great bass trapping.
2. Make sure both side walls have equal amount of absorption, and at the same height and distance. In other words, symmetrical. Otherwise, I can hear the difference. My side walls are covered about 40%.
3. I like the back wall about 50% covered with absorption. I hear this difference in the dialogue.
4. I use 3" rock wool at first reflection points, and 2" almost everywhere else.
5. Ceiling clouds, I have not tried, but I want to try the at the first reflection point on ceiling.
6. With the amount of absorption I just mentioned, the amount of power you need to reach the same SPL is greater. Meaning that if you'd regularly play movies at 60% of the receiver/amp capability, you'll need to run it at 75%. But that sound will be way more clean and linear.
7. I have not used REW yet. I have the app, but no mic. I would love to measure my room. Decay times, etc. But to my ears, this is the best my room has sounded.
What do you guys think?
Thanks for sharing. My turn now
1 - Managing base decay: I have had all this done that you are doing before. I have had Lin but I just went with 1". I don't think it really matters if you have 1" then plastic and then 1". Using just 1" will absorb High frequencies just fine. I don't think making it 2" with plastic will help will Low/Mid frequencies. I use REW. In fact, I used it by placing each panel and then took reading to see what it does and then added more or removed based on what I saw. So, if you want to make sure the room decays withing 300ms, you take reading and start observing. When I took all the panels out, the dacay was going beyond 450ms. Then I added 8" 703 on front wall corneres and also in one back wall corner. Then took reading and then installed the ceiling panels (3 4" 703) and 1 4" 703 on each side side wall on 2nd reflection. Took reading and all the mid-bass (150 onward) was well within 300ms. Now if you have anything under 150 going beyond 300-400ms, you'd have to add a lot more to tame them down. In my case, I didn't. For some reason, my room does resonate at 60Hz but I think its my mic (will post question on REW thread). Other than that, my whole waterfall graph (that shows decay) is within 300 ms. So that takes care of bass.
2 : Room Reflection. So after installing bass traps (or Mid-bass traps I should call), I moved my target to room reflection. At this point, I already have 1" lin on front wall and 50% back wall covered with 2" 703 and corner bass traps and panels on top and side wall. Checked the Impulse response. From top of my head, it should be below -20. When I checked, I hardly had any spike going above -20. Now, there has been discussion where some say to have Lin on front wall and some say that you are damping the room too much if your front wall is completely covered. So, it was time to find out. I took the whole 1" Lin off. Then put 1 2" 703 behind C starting from its tweeter height going up. Then took reading and guess what !!! I didn't see any noticeable change in reflection. So Lin really wasn't taming that much for me for early reflection and I think it was damping my room.
Now all that is purely based on what REW is showing me. Listening is obviously the final answer to all the changes which I'll be doing over the weekend. As of now, I have 3 corners covered with 8" 703 with front ones from top to bottom and back only up to ear level (since I don't want it to absorb L/R reflection). Then I have only 1 2" 703 panel on each side wall parallel to each other and 3 4" panels on ceiling (1 for L, 1 for R and 1 for C). Then I have 1 4" 703 behind C on front wall starting from tweeter to all the way up. All this has gotten the low frequency under control within 300ms and also the reflection.
BTW, I do have AT screen but its not weave. Its a Perf screen with 1.3 gain (amazing . With screen on, I do loose 8db on high frequency which Dirac (room correction system) fixes for me. I guess the point I'm driving to is that Lin on front wall might not be necessary and its definitely not for helping out with mid bass. With a setup above 5.1, we do have speakers firing towards the front wall and it might help absorb them. But I don't want to just put it there and go with it. Instead, I want to first listen to my room and if I find that its too reflective, only then I'll add more absorption. This will ensure that I'm not over absorbing. My speakers are 106dB sensitive so I can easily over damp my room and crank up the volume and they won't give up on me.