No they don't. Those Altec 19 speakers were designed long before super amps. They are deafening with a 10 +10 watt tube amp.
There is one thing your calculator is not allowing for and that is the fact that these speakers are highly directional, so you get one Hell of an earful. So far more of the output ends ups in your lap so to speak and less in the room as a whole than speakers of our time.
The horns on those speakers are the same as the horns in the Altec Voice of the Theater speakers. Those speakers filled cinemas that were bigger than now with 10 + 10 watt tube amps, because that was all they had.
I strongly suspect that something is faulty with his set up. If that rig was working correctly, there is no way you could stay in the same room with those speakers and cause his unit to shut down.
I remember there was a big event in St Paul's cathedral in London before the super amp age. The outfit called in could not fill the space. So Donald Chave CEO of Lowther was called in and filled the place comfortably with four very high efficiency 6" full range horn loaded drivers, powered by a total of 40 watts Lowther tube amp, amplification! Yes, Lowther made amps and speakers back then.
My father clearly remembered that episode. In my home parish of the English Martyr's Strood UK, the 1963 Church designed by a close friend of my father's who was a fellow officer with him out in India in WW II had a very difficult acoustic that defied the pros to install a PA system that was any use.
Well it also defied me. This is the interior.
Now although built not that long ago in 1963, this building is listed. In the UK this means it is considered of special architectural merit and significance. There are very, very few listed buildings from that period. Anyhow you are very limited as to how you can alter a listed building in any way. You can't hang big ugly speakers. After failures of the pros, I designed some slim column speakers for the two columns either side of the sanctuary. This was a total failure.
After this and other failures, my father in his eighties designed and built those square looking speakers you see at the ends of the arch over the sanctuary. There is one 6" high efficiency paper coned Lowther full range driver in each. He built front loaded horns. What you see is the mouth covered with the light grey speaker cloth. The horn is quite long, but you don't see that unless you are underneath or behind them. The back of the drivers are open and exposed and not enclosed. When I asked my father how he worked out the dimensions of the horn, his answer was: - "It looked about right!" Anyhow it was totally successful and fills the place with sound driven by a small solid state mono PA amp! I have played quite a bit of choral music on them and they sound surprisingly good. However the main point is that these speakers were the first to let you actually hear the celebrant and readers, in that very difficult acoustic space.
Horns are just not like other speakers and seem to me not to have read the rule book!
