Your right about you don't have enough, a few tube traps is not going to cure a slap echo problem. I have the same situation in my room and even 16 tube traps didn't totally eliminate the flutter echo. Diffusion is the key, you don't want your room to dead, but you don't want the echo either. Keep in mind that finding just the right spot can dramatically effect the amount of echo you are getting.
In my room the perfect placement of 2 wall panels on the back wall reduced the echo by about 50%. Even after placing 16 tube traps, which do improve the sound in other ways, didn't work those 8 inch wide wall panels spaced on the back wall behind the listener really cleaned things up.
In my room the perfect placement of 2 wall panels on the back wall reduced the echo by about 50%. Even after placing 16 tube traps, which do improve the sound in other ways, didn't work those 8 inch wide wall panels spaced on the back wall behind the listener really cleaned things up.