QRZ Forums. Just prowling around on the net and ran across something interesting. Did you know that Astatic microphone company is still in business. I am sure the would sell them all. I also wonder why they haven't made any after market microphones for any current ham equipment. The never went out of business.
Shure introduced the Controlled Reluctance Transducer element in The elements had a unique design that made them immune to temperature and climate conditions. It consisted of a brass disc that was used as the main support for the built in transformer, magnetic assembly, diaphram, armature assembly and cover. It was described by Shure as being a high output microphone with good response, high impedance without the need of a transformer that had its stability assured by unique control of the reluctance of the magnetic system. Years later they were called Controlled Magnetic Transducers. Shure described them as being pressure operated units using the balanced armature, controlled magnetic principle.
I started out with a Shure 55A, still the pride of my collection, and went on from there. I now have over 20 vintage microphones dating from the s to the s or so. There's so little information available to the vintage mic collector, I've found. I have not come across a decent book on the subject, which surprises me because there seem to be quite few collectors around. None of my mics are for sale and I'm not really in the market for more right now, but I'm always interested in learning more about these objects and the history of the companies that made them.
That said, Elvis was more known for using the Shure 55 microphone and the post office even made a stamp of him using the The Astatic 77 was designed for high quality broadcasts, recording studios and public addresses. Depending on what the microphone was being connected to, users could switch between Impedance levels.