Well, to answer my own question about sticking a more expensive emminence driver in an empty avatar cab I started using winISD and looking at the curves. It struck me the non-custom cabs are tuned quite high giving a 'hump' at 50hz (in the case of B15), whereas a lower tuning smooths out the curves on the drivers it seems... so presumably you can do that just by altering port size? For those not interested in the carpentry of cab-building, customizing existing designs on pre-made cabs seems like a fun way to proceed for the tinkerers among us, and learn more about transducer engineering along the way. So, maybe folks already have workable designs ready they have tested (or even just sound theoretical ones)? Could they be put on the web somewhere? Like - "buy driver x, increase port length on avatar cab by y inches and you get z increase in 30hz bass response" I mean, with the right drivers, a 210 or 112 could be nearly flat down to 30hz.... at the expense of sensitivity. EST-Ltd ---- did you use ready made cabs for your 12inch subs? How did they turn out? One idea I like is have a small flat full range cabinet (lets say like the B112) which can be used for hi-fi, parties, home theatre, instruments *whatever*. It certainly wouldn't be audiophile quality, but would have better tweeter and lower bass than a standard bass gtr cab or average PA cab. For volume you just buy more of them and daisychain. Obviously not many hi-fi's have 400 watt amps, but then you wouldn;t *want* gig-volumes in your home very often.