Does anyone else notice a lack of bass when using Trifield or is it something I've set up wrong?

I'm using a 561 with crossover set at 80Hz and a REL Storm III subwoofer.

All speakers are set to small and I've calibrated the levels with a sound level meter.

I've noticed that all sources (CD,TV) have very little bass when in Trifield. If I switch to PL2Music or Stereo, the bass comes back again.

Anyone got an explanationfor this??

Thanks
Chez