Thanks guys. Rarely in this hobby, it seems, is there a hard and fast rule. With my space opening to a larger area, I haven't noticed too much bass boominess. It's mostly a problem of echo I'm dealing with given all the wood surfaces. I do have fairly heavy curtains, mostly for light control, so that may help minimally. I'll probably incrementally add absorption and do a little diffusion behind the main speakers.
Well there actually are hard and fast rules but not in the way your probably thinking. As you mentioned you are searching for one size fits all general guidelines and that is what I would hope to apply as well.
Unfortunately actual room treatment is specific to that room so the treatment becomes frequency and amplitude dependent. That requires measurement and data crunching. So instead, please forget everything I just said
and use some common sense applications as you had hoped to anyway
Echo usually means the secondary and possibly tertiary reflections are arriving too quickly to your ear for your mind to process and invalidate them from the original source information. Absorption or diffusion at specific reflection points will benefit the invalidation process and enhance the believability of the original info.
Frequency aberrations can possibly be reduced by the same treatment, BUT not necessarily, which is where patience becomes tested. Speaker placement as well as the placement of every other artifact in the room can possibly change frequency behavior, so if you move stuff around and like it better, don't forget to recheck your previous reflection point work.
Would love to see some pictures along the way if you think of it.
Oh also those curtains can be a great help. Where is the window they cover?
