I just replaced the more modest EV 12TRXB "triaxial" (actually woofer, tweeter, and wizzer cone) with the more robust 24 lb "coffee can" AV 12TRX driver in one of my Aristocrats. Used the original AV crossover and volume control on the tweeter. I'll do the second speaker tomorrow, but took advantage of having a mismatched set today to compare them.
Well, surprise! The biggest difference is not that the B version is less efficient and does no go as deep. The tweeter is the most striking difference. The 12TRX has a much better tweeter that gives it really sweet vocals and more solid bite to trombones on Sinatra's Summer Wind. Vocals on Morning Has Broken are to die for sweet and convincing.
We will see tomorrow when I replace the other 12TRXB, but my sense is (from a few minutes of listening to some Buxtehude Trios, lounge jazz, older folk-pop, and a little Cream White Room Ginger Baker magic) that these Electro-Voice Aristocrat cabinets with the better tweeter in the 12TRX speakers are one of those amazing combinations that actually reproduce the human voice in an utterly convincing manner.
And that is no small feat! SO even if they have some obvious deficits (being from over 50 years ago) of dynamics, sheer volume, and transient snap; it is likely that for the sheer joy of listening to singers such as Nat King Cole and Maria Callas they will find a permanent place in my home. They are stunning vocal speakers!