Originally Posted by OKGeek
Thanks, man! I didn't think about RT60 uniformity, so it's great you've mentioned that. Currently in design stage, so measurements will be available a bit further along the way. Will definitely post here.
Awesome. That's for sure was not on my radar. Impression was that the more bass traps I have, the better, but I see, that not all basstraps are created equal
RT60 Uniformity is important as a means of understanding the listenability of a room. In more tangible terms, when a room has really good decay in the mid and high frequencies, but poor decay in the bass, a room may have clear dialogue but sound boomy. Conversely, a room with good bass decay but poor mid/high decay may lack speech intelligibility, may have audible echo issues, etc. Notches in the decay can make it sound unnatural. The actual decay of the instruments or recording are already on the recording, so you don't want the room to contribute to that.
I really think that the main reason for keeping the RT60 values over .2 seconds is really more because a room that is too dead is uncomfortable, and the reason to move music rooms above .3 is just because a lot of recordings don't have good "room sound" unless they are a more natural or acoustic recording. It also wouldn't be possible to get bass decay that low and I do think having an even/flat RT60 value over the widest possible frequency range sounds more natural.
In terms of bass trapping, the more the better is mostly true, but certainly not all bass traps are created equally. Corners of rooms are very special places acoustically and need to be treated in very special ways. It's a lot more efficient of acoustic material to simply place 4"-6" panels across a corner instead of chunks, and they actually absorb, overall, very similarly to solid chunk absorbers, however if the material is too thin and doesn't break up all paths that the waves reflect in, you can get a less ideal absorption. Some commercial options have solved this simply by placing "shelves" of acoustic material up the length of the trap at periodic positions.
My main concern with over-use of full range bass traps is the RT60 problem. As an example, the GIK tritrap is nearly flat from 80hz to 250hz in absorption. The Monster bass trap is similarly flat out to 500hz or so. With numerous 4" panels also in the room you can end up with too much absorption at 200hz to 500hz and so its not uncommon to see a notch in the RT60.