I have played through this cab. It is a beastly beast. I believe @Mike Arnopol also mentioned that the tweeter in this particular cab was a pretty special deal, but I don't know any specifics about it.
Mine was one of the first with multiple tweeters in the rear, but I am sure this is a serious improvement as Mike is always innovating. I won't let mine go just yet as it is a hammer outdoors, and I am not a PA backup star player. I have filled block parties w/o PA support at SRV and Hendrix volumes. Stephen has said the original 48 is still one of his favorites. Can't go wrong with this at a great price below retail. The 48's have the vortex magic in spades! As far as comparisons go thumbs can tell you as he has been a MAS owner of many cabs I believe.
4 ohms.....wow
If I played bigger stages and higher volumes I would buy this in a heartbeat.
My opinion here, but I think this is probably the best standalone upright bass cab for loud / big stages. Totally biased, 5 of my 6 cabs are built by Mike.
Mids are the same as the Mas 18. On both cabs the mid/tweeter is crossed over pretty high. Around 3khz. The mids are more articulate than 10 or 12" based cabs