Volume is 74.8ltrs so allowing for drivers and other bits in there should be close to Volts specs for ported design. Info downloaded from their site a few years ago gave Volume 70ltrs, Vent dia 7.5cm, Vent length 11cm, should give -3db 35hz .
Thanks. I'll revisit my enclosure sims and see if I require a different size. My design goal is a large bookshelf/monitor with very good dynamic range in a domestic setting, so size is somewhat of a constraint.