The 18Sound 18LW1400, Eminence Delta Pro 18 and the Void 18-1000. Other drivers have been mentioned but yet need to be confirmed.
The 18LW1400 and V18-1000 have both been measured in the 3th prototype, the current release however is the 5th protype, the 4th being Cubo 15. The 18LW1400 measured a higher sensitivty then Cubo 15 over the <100 Hz range, crossover around 80 or 90 Hz sounded best.
The V18-1000 haa a tremendous kick. Hearing the kickdrum from an amplified drumset crossed at 125 Hz puts a smile on my face every time.
Cubo 18 Extended is an upgrade if you will, that, for most drivers will result in a smoother frequency response. Some drivers however have smoother response in Cubo 18 Standard.
The Fane 18B600 works in both yet is a dB more smoothed in the extended version.
Those drawnings were from Cubo Sub, the 1st prototype IIRC? Soonish I'll be prototyping the 2nd (and 3th) prototype, of which the third is similar to the 1st you got. The 2nd prototype will hopefully be more versatile in placement..
Cubo 18 Extended: 40 Hz and up in 249 liter. Cubo Sub: 30 Hz and up at 1.5 times the size of Cubo 15 (sensitivty on both models is equal on average). Choose your game smiley1