Embiggening the Altec 620. Thoughts/experiences with >9 cu ft cabs for Altec 604-8g?

I think it's a bit of an art form getting resonate cabinets to sound good across the spectrum. Shindo (Harbeth, Audio Note and a few others) are controlling the vibrations to happen in a very specific frequency range that does less harm than vibration in other "more essential" frequency ranges. The type of wood, veneer, size, and even the internal paint used in that second Shindo photograph are tools to move that vibration where the designer wants it.

Build, measure, listen, repeat... A big endeavor for the diy'er. I appreciate you brave souls doing and sharing your experience. I think the reward is pretty spectacular with the way these cabintes done right can excite and energize a room.