Isolation or treatment boundaries (Room ratios and angles)

There are two types of boundaries in most of CR designs I've found here: - isolation boundaries (eg gypsum board) and  -treatment boundaries (eg the edge of a slot resonator or bass trap). If I want to satisfy a given room ratio, am I adjusting at the dimensions of my isolation boundary, or my treatment boundary, or both? Flutter echo from parallel walls is bad, so can I get away with angling my treatment boundaries, or do I need to ensure my isolation boundaries are non-parallel, or both? Same question for reflection free zone: Should I angle my isolation boundaries to make sure first reflections miss the mix point, or is it sufficient to angle treatment boundaries? My studio will have no soffit-mount speakers, and I've been trying to create a first-reflection-free mix point but it seems impossible to do without making the room very wide... Am I missing something or is this a common problem?

from a mode perspective, the isolation walls is where you determine your room measurements. you can angle the the isolation walls, the treatment walls, or both as needed. depending on the space, sometimes the straight walls with angled treatments provides more depth, in some cases the angled isolation walls is enough.

"If I want to satisfy a given room ratio, am I adjusting at the dimensions of my isolation boundary, or my treatment boundary, or both?" To satisfy a given room ratio you have to have a ten foot ceiling, that ceiling point will be ten foot from finish floor elevation to this same ceiling. Ten feet tall was the measurement that Loudon and Sepmeyer used in their measurements of room acoustics. Speed of sound (1130) / 10 (feet) /2= 56.5 Hz, the equivalent to approx. A1 on the piano. When these ratios are altered, they change the response of the room which is not to say do not use them, but things will change so your mileage may vary, so to speak. So the hard interior boundaries of the room are what your measurements should reflect. This can be a tedious process since you have to layout or draw the actually interior finish and then step out the thickness of the sheathing (to include however many layers you will be using) and then the framing so you can have a baseline idea of where to pop that first line :)

I did not realize the room ratios were for 10' ceilings! Thanks for clarifying that. My studio will most likely have an 8' ceiling unless I can find some major cash to underpin. I'm about to start a new thread to show a design I came up with based on the 1:1.4:1.9 ratio for an 8' room, but please do let me know if there's a preferred ratio for such a ceiling height. Thanks!

The thing with ratios is you can loose your mind worrying over them and the bother needn't be there. There are literally dozens of room ratios. The best thing about any ratio is at >least< you are not developing a square or worse, a cubed shape room. So while the ratios are not scalable and seem to depend on a ten foot hard boundary to be the most "optimized", don't get too caught up in the hype, it isn't worth it. Even a square room can be treated to be pleasing to the ear...but I wouldn't construct one :)