You can mount minitraps horizontally rather than vertically, as you have them now. ie...with a long end against the ceiling rather than a short end.
I did try holding one of the Realtraps across the back wall-ceiling interface (much to my wife's amusement) and it had less of an effect than in the corner, where it is now. (But of course it still had some beneficial effect.)
Quote young david:
Wouldn't be too worried about the top end - looks fairly smooth apart from the roll-off after 10k but if that's not the mic then maybe your new monitors will help. I think it's normal to have a lot of narrow peaks and troughs but as long as they're narrow it's not something that will affect your judgement. Besides, the wavelengths are getting so small up there that if you move your head a centimetre it will all change anyway.
Really? The high end sounds so much more lifeless than in my old (bigger) room. Just sort of dull, lacking crispness, and generally worse, like when my old room had no treatment in it at all.
The mic was a Rode NT2A in omni mode and the preamp was one of my Fireface 800 preamps (used as a preamp only, sent to the Tascam US122 sound card I used for testing) so I don't think the mic is responsible for the high-end rolloff.
I've had a suggestion to put 6 GIK 244s up-- four across the wall/ceiling interface and two on the back wall-- but I am still worried about my top end.