Yes Gonk, I think (after a night's sleep) that it would be silly of me to think that Velodyne would have goofed up like this...so I'm going to put the mike boom exactly in line with my head to start with.
(Standing waves can seem to shift back and forth even when I bend forwards).
Also, I won't use the Self-EQ now at all, if only for fear of blowing up the sub...
And this time I will use the big REL Strata, a nice dry sub www.rel.co.uk
Currently trying out the Q2 KS-Digital QSUB2 dipole sub (2 speakers blasting away into each other's cones, effectuating a diffuse and -they claim- less standing wave - prone emission from the front and rear ports).
Scanning with the tone generator I noticed this sub rattles up to 23 Hz (the REL doesn't do that, it rattles the room contents when going down from 25 Hz, but still keeps sounding tuneful until changing to thump-thump-thump below 15 Hz.

Plenty to do this Sunday!
Pl