N802 + Velodyne DD-18???

My room is 15x21ft and my sweet spot is 11ft from speakers which are 9ft apart and 3ft from front wall. I have some bad modes on listening position (-10dB@50Hz / -4dB@80Hz) and other frequencies are pretty flat down to 25Hz. Yes, I tried move speakers around as well with N801D. Reverberation time is good within whole bas range (1.2sec) and I experiment with some absorbers. Still I think I need Velodyne!

Thanks guys, but I also tried different amps, Behringer digital EQ and Copland room correlator. This equipment improves amplitude, but in same time you have problems with distortion, handling, not to mention converters who are responsible for all others things... My point is: I don’t think that anything will fill 10dB dip, but can contribute. I tried with lower class subs and I had better results if you compare with other mentioned experiments. Finally, N802 need some extra energy below 30Hz. At least in my room!

I actually planning to build new box for DD-18. Goal is to look like hi-fi stand (invisible) with down-firing base driver, like Rel.