PERFECT 10w x 18d x 9h room, any good?

Magfan
I understand, not sure you see what I was actually saying.. Too small is going to be too small an acoustic space regardless of a Phi ratio. I agree there is definitely an optimal ratio I am sure.. Point being if your forced into a room barely as wide as my bathroom you got a problem no matter how good a "Ratio" it is was the point. But the smaller the area almost the more the acoustic treatments somebody might end up needing in the end to correct it.

Can't argue with that! Too small IS too small and that size brings some awful problems of its own. I had my Maggies in a large closet once....about 11 x11x 8 and it was the worst. I had to swap them L/R to get the image correct...
10x18 is pretty small, but not a deal breaker. You're not going to get big speakers in there and you may end up doing a short wall setup and listening near-field, but for a personal listening space it can work. Don't put your back up against a wall, either.
The good news is that you have only so much wall to treat. That will keep expenses down.
The only thing I'd wish for is when starting with a clean sheet of paper, to get the fundamental dimensions right which may help minimize the expense of later treatments.

My 10*18 room has just 3 very small windows up top since its a basement room. I do not think its a concrete room and the floor is carpeted.

Another issue with this room is that i must put integrate the sub into it as well.....

AHHHHHHH....this is a Pain in the a##......but i might as well try it and use the cardas rule as a general approach.

forgot to mention that this is a fully closed room on its own....so basically a pure enclosed rectangle box with a door.

Any basement room will have concrete or stone under whatever is used inside the walls. Floor is likewise concrete, no matter what you are walking on.
Also, you never mentioned the ceiling. Open joists? Drop ceiling w/acoustic tiles?
With 9feet of ceiling you might be able either build a subfloor or treat the ceiling....or both.
It's going to be a pretty LIVE space unless properly treated.