I'm not convinced of the necessity of bass trapping at the reflection points, as it's usually going to be the higher frequencies giving you first/direct reflection trouble. Bass issues tend to be more of a function of the room reflective dimensions and corner bounces than of the room's primary reflection points.
Then again, I'm not a pro acoustical engineer, either. But just from personal experience, I'd give three pieces of general advice *just to start out with*. Others may see it different than I, I'm not a burning bush on the mountain here:
First, unless you are trying to build a professional studio for professional - meaning business - purposes, I'd take it in stages rather than a balls-out, grand plan from the start. And if you were going down that path, I'd find another room to start with.
But otherwise, if you're just looking to make decent mixes for yourself or your band, while everything that John, Ethan and I say are absolutely true, and are theoretical ideals, honestly there are a lot of people out there who can make perfectly good mixes with slightly less than theoretical ideal conditions. And I think surrounding yourself with a defensive rampart of bass trapping gobos and broadband absorbers may be overkill. It may not. But I'd work my way up to something like that only when less than that is not working out for me.
Second, remember that any room with four walls, a floor and ceiling, actually has 12 corner joints not just four. People tend to think only of those corners between one wall and the next, when those between the walls and ceiling or floor are corner joints just the same. This doesn't mean that you necessarily have to bass trap all 12 corners, but often when you find that two or four corner traps hare helping, but not enough, that maybe adding one between the real wall and ceiling or front wall and ceiling, or whatever, may be the ticket without going overboard elsewhere.
I forget now what the third one was
G.
