how big a speaker can you put in an 11 x 11 room?

No doubt I'd put a pair of OHM Micro Walsh Talls in there, build around that and be done. They are explicitly designed to go into small rooms in particular.

I use slightly larger OHM Walsh 2s with OHM Walsh 100 series 3 drivers in a 12X12 room. These work to the max in the room, but I suspect smaller and less expensive MWTs (or their shorter brothers, the Micro Walsh Shorts in some cases) would suffice.

it is only the bass response of the speaker that will cause problems, so if you're willing to do either of the following, it will greatly expand your options and ability to get a larger speaker to sound good in that room:
1) room treatments (bass traps in corners, all the way to the ceiling)
2) Rives Audio PARC (an eq for bass frequencies) or similar type product (Tact, etc)

if your budget is flexible, buy a larger speaker & have the room measured after setting up. determine where the nodes are, and address using either 1 or 2 above. the PARC is quite flexible and will remove room nodes where you have too much bass by targeting specific frequencies.

you will have too much bass in that room unless you address it. just dont be a passive victim; work for good sound, and you can definitely get it, using full size speakers in there.

(my room is 11*15 and i use Wilson WPs in it w/ no trouble, but take a look at my system pics---room treatments everywhere. if i did not have the ability to have room treatments everywhere, i'd have the PARC. if i had neither, it would sound terrible, which i know from experience).

I have a very vanilla 12X12X8 office/listening room. Concrete foundation with thin carpeting, drywall, typical office furnishings including couch to listen from (photo in my system posting).

Ive tried B&W floorstanders, Maggies, Triangle and Dynaudio monitors, and large and small OHM Walshes in that room.

The smaller full range OHMs currently there work best both in terms of sound quality and overall utility in a small/cramped room, followed by in descending order of fit Dynaudio or Triangle monitors, Maggies, B&W floorstanders (P6s)and lastly big OHMs (just too big for such a small room though they sound great).

I guess it's an Ohm Fest regarding responses, and I have to chime in as well. I bought the Ohm Micro Walh Talls because as a military spouse, I move a lot and have to plan on small rooms.

I feel the MWT's work extrememly well, especially for near-field listening. My current room is maybe 13 by 16 (I can't remember exactly), and they're great. But I bought them instead of the S-100 because chances are they'll be in a 10 by 10 box at some point.

Another good possibility is the Micro Walsh Shorts. Those along with the Micro Walsh Walls are on my list of possibilities if I want to expand beyond 2.1 in a small room.

John at Ohm no longer recommends the Micro Shorts to his customers. When I talked to him about buying mine, he purposely steered me away from the shorts, and recommended the Talls. Personally, I think that the Shorts would be too close to the floor and overall sound would suffer. If anyone out there has a pair of the Shorts, I'm curious as to how they sound to you. I love my Micro Talls, and the speaker being on ear level sounds great, but when I stand up, the sound changes considerably. I suspect that would be the case with the Shorts, since they are already below ear level even in a seated position. I could be wrong, Anyone got experience with the Shorts?