Here is a close up of the whizzer and tweeter inside it, notice the felt creating the transition.  The surround for the driver is almost like material for a speakers spider.
Under the back name plate is the simple crossover of one paper in oil capacitor, this is also where the bolt holding the tweeter attached is located.
A side view of the heavy cast aluminum frame supporting the moving parts of the 12trxb, with such a frame resonates are reduced to almost nonexistant.
On the speaker are three binding posts, one common marked by a black gromitt, and two positives marked by red.  Usually the two positives are tied together as pictured.
Electro-Voice was way ahead of their time in frame construction, and they are still very good even by todays standards.  All 12trxb's were hand made and of the highest quality, even today they are still amoung the best speaker available.
One of the few down sides about the 12trxb is you can not change the voice coils out in the tweeters, as you can in the regular T-35 tweeters.  It is good to have a spare, but I would not recommend running wattage of such high levels to risk burning out a voice coil.
12trxb Features, and Information.
Many Electo Voice speakers share many of the same features as the 12trxb, I prefer the ones with thes heavy aluminum cast frames, as they seem to have a slight advantage with resonances.  There are still plenty of these speakers around, and for the level of fidelity they produce they are a real bargan, one of the best kept secrets in high end audio, but don't take my word for it listen for yourself.
1