Originally Posted by
Steve Schell
Vern it seems you have thrown us off the chase with the pictures in your post #2. Those show an Altec Lansing H-808, which is a different horn than the one shown in post #10. They do have similarities, but are from different manufacturers.
The Altec H-808 openings are roughly 110cm square, so your horns are larger with likely a lower cutoff frequency. My guess is that they are English or European, 1950s vintage, but I have never seen any exactly like them before. Are the threads 2.5 inch with sixteen threads per inch? This was the Academy standard as innovated by the Fletcher Horn System team at Bell Labs in 1933 and maintained by Lansing and RCA in the USA until the early 1940s.