RCA MI-12424 Monitor Question

[farleybob]

One of the first vintage speakers I ever found was this MI-12424. I've always had tough luck finding information on it, though. The folks I bought it from said it had been surplused by the government in the 50's and the gentleman bought it. It was painted with the Asian dogwood motif for some WAF and he added a Jensen RP302 supertweeter. Anyway, I've not seen very much about this speaker. I've found information showing it with a MI-12432 woofer, but the LF driver that I have is an MI-9439. It sounds great, but I kind of like w/o the tweeter attached. If anyone has any information about this speaker of the driver, I'd really love to hear it.

[stephane RAME]

http://www.oswaldsmillaudio.com/archive.html
http://www.oswaldsmillaudio.com/rcamuseum.html

Stéphane

[farleybob]

Wow, I don't know how I never managed to run across that site over the years. Great archive! Thanks.

[Steve Schell]

Farleybob, I saved your thread nearly two years ago and intended to reply, but apparently neglected to. Sorry. Your speaker is quite rare, though I have seen a few of them. It was built immediately postwar AFAIK, perhaps 1948 or so. The late RCA engineer A.J May had a hand in the system's design; I'm not sure to what extent. He told me that horn used in the system was one of the first commercial uses of the radial horn, an invention of RCA engineer John Volkmann. A.J. was his understudy and assistant at RCA. All of the more familiar radials- the RCA theatre horns MI-9594 and 9595 (designed by A.J.), Altec 811 and 511, Ampex/JBL 2350 and etc.- were introduced after systems such as yours and experimental RCA systems installed at Radio City Music Hall by AJM and JV had proven the merits of the design. So, you have a significant speaker. The compression driver is a seldom seen model produced by RCA. As I recall it has a phenolic diaphragm and a triangular shaped cast metal structure behind the diaphragm. The woofer seems to be a variant of the MI-9449 theatre model.