tube traps didn't help

I had the luxury of being able to borrow a slew of old some worn looking tube traps from my local hifi shop

I have a 27 by 15 (widest dimension) which cuts down to 12.5' on the ends (notched in closets and hallway openings on both extreme ends. I listen along the far wall.

I borrowed two 16" rounds two 9" rounds - went in front corners
and 4 9" half rounds (behind speakers and on back wall where the closets stick out (to damp the reflection back to the front wall.

I think my problem is a mile slap echo and the tubes didn't cure it. The results in the lower frequencies were very minor for a major overhall of my room. It seems I didn't have enough of the traps higher on the walls (all 4'), stacked front 9" on 16". And no treatment immediately behind my couch on the back wall

I've started using fake ficuses as diffusors on the side reflection points which are minimized by the long wall offset. And I'm looking at some echobuster panels to cure the back wall bounce etc.

any suggestions

thanks

tom