Secondly, what exactly are the new "digital" Velodyne HGS subwoofers? What will the difference be between them and the current line?They will be significantly more expensive than the HGS series (I believe the replacement for the HGS18 will be somewhere between $4-$5K. They are supposed to have a gizmo that automatically flattens the FR (no more need for an equalizer). I am probably oversimplifying so others please feel free to correct any blunders.
I had no idea, that the Velo 18 was such a brilliant performer down below 20hz, would the 16-46pci outperform it?I seriously doubt a 16-46 PCi would outgun the Velo 18 below 20 Hz, but I'm quite certain a 16-46 PC+ would come darn close. The 16-46 PC+ offers a solid 5-6 dB advantage in maximum output below 30 Hz over the 16-46 PCi.
FWIW, the Ultras in the Weatherhead shootout were equipped with the original driver. The current production driver for the Ultra is the TC Sounds TV12. The TV12 holds a 1.5 dB advantage over the original Ultra driver. So when you are crunching the numbers for how badly a single or dual Ultra stomped on the Velo, just add 1.5 dB to the Ultra number.
So to "re-crunch" your numbers, all other things being equal and using the Weatherhead review as a framework:
Velo 18: 101 dB at 20 Hz (Weatherhead)
Dual Ultra w/original driver: 110 dB at 20 Hz (Weatherhead)
Dual Ultra w/current TV12 driver: 111.5 dB at 20 Hz (estimate)
Single Ultra w/current TV12 driver: 105.5 dB @ 20 Hz (estimate)
Single PB2+ in 20 Hz tune: 108.5-110.5 dB at 20 Hz (estimate)
I think the thing to remember is that the PB2+ is clearly tailored to generate prodigious output in the 25 Hz and above region, albeit with tuning capability below 25 Hz with some associated loss in output. It is not designed to drop into the teens with extreme authority - the best SV sub for that job is the 16-46 enclosure.
SV comes as close as any company to providing a "one sub does it all" concept. With that said, each model and each size enclosure clearly has an intended optimum operating range. It is up to the user to select which sub best fits his needs, and run the sub in the stock configuration most of the time.