speakers in a bad room

Dude, sound waves are sound waves. Pull out your physics book. Get a thick rug, fill a book shelf at the back of the room (with books), and buy some acoustical treatments to dampen the initial reflection points!

I think I agree with Jeff. Rugs and tapestries will offer greater sonic improvements than expensive speakers.

18 X 24 is a bit small. However ages ago I had a system, (mono because stereo was not yet invented) in the concrete cellar of a New York City house. When I played dixieland jazz it was great, because the jazz dives that I visited at the time were all in cellars.

I agree that the reflections will be wicked, wicked good perhaps! To get the full effect get a speaker with a honky horn midrange.

Today my system is much more refined, and I listen to a lot of classical chamber music. But when I play jazz, I'm not sure it has quite the impact of that first system long ago.

The room will need some form of acoustical treatment, but I suggest you mate that with a speaker that is designed with narrow dispersion characteristics which you can set up for near field listening. This will probably limit you to single driver or two way speakers.

Onhwy61 gives good advice that had not occured to me. Listening in the nearfield (which really means with you and the speakers forming a near equilateral triangle, about 6-8 feet from the speakers) significantly reduces room effects.

Also having the speakers well away from the rear and side walls (like 2-3 feet) and toed in towards the listening position will all help. Hopefully this will work for you aesthetically .... it doesn't work for my wife so I have a dedicated listening room in the spare bedroom.

Also a highly reflective room will tend to sound bright, and will not tolerate loud music without starting to sound muddled. Hopefully you enjoy listening at moderate volumes.

As for suggestions what is your price range and the rest of your system ?