First post here for me, i apologize for the length... I have been building my own cabinets for a few years now and i wish i would have found this place and searched it years ago! Does, anyone have any theories on how Mesa Boogie determines cabinet size & port demensions/tuning freq. for the Powerhouse 1000 cabinet, the version that is one common cabinet with 4x10+1x15? After exhaustive searching here, and of several news groups etc., the only thing i have come up with is that "mesaboogie hand tunes each powerhouse cabinet" but no theories or practical examples for designing a cabinet of this type. IMO the best sounding cabinet i have run across for the kind of music i play is the PH1000. Anyway, about 4 years ago, I put together a cabinet with the PH1000 configuration, but was never comfortable with not having a solid theory for determining porting for it. According to my own subjective testing (my ears and bandmates) the cabinet was louder and lower than the previous separate 4x10 and 1x15 cabinets i had built using the same drivers. I'm getting ready to build a new cabinet with new drivers and want to build another of this type, but wanted to see if anyone has ideas on how different size drivers with differing TS parameters would share the same cabinet air volume/ports.