First, have the RCA checked out by somebody who knows *exactly* what they are doing, and whom you can trust not to lie to you. It is potentially worth a ton of money. The RCA on Johnny Carson's desk could be worth as much as $15,000 in good condition.
The 55's- OK, time for a history lesson. First, no matter which version they are, they are not worth a lot of money, about $150 max, more likely less. So many of them were made. Mine was used by Doris Day and Roy Rogers, and isn't worth much.
The Shure 55, or "Unidyne", was the first unidirectional dynamic microphone commercially available. Introduced in the late 1930's, it came in 3 versions-55A (low impedence) 55B (middle impedence) and 55C (high impedence). In the middle 1940's, they were replaced by one model, 55S (for switchable) which had a low, middle, and high impedence switch. They were discontinued and replaced in the early 1950's by the Unidyne II (?55SC, I'm not sure about the model number). This was called the "small unidyne". and later simply as "the Elvis mic". It was later discontinued, and many years later (?early 2000's) Shure came out with a nostalgia model, the 55SH, which is based on the SM57 capsule, and sounds nothing like a 55 (which is a good thing). There is a guy in Florida who runs a business called "The Mic Doctor" who specializes in refurbing old 55's, which is absolutely necessary. One, because the colored silk inside the steel housing fades after many years, and can even grow mold, but more importantly because the capsule was shock mounted with foam blocks, which after many years, turn rock hard, or even crumble to dust.
The mic doctor can return the mic to spec, and can provide the archaic amphenol cable that it uses, for a pretty reasonable price. If you do that, will you get a great mic? No. But you will get a piece of history- Douglas A. MacArthur's stirring speech before the invasion at D-Day, Harry Truman's "A date that will live in infamy", Marilyn Monroe's "Happy Birthday Mr. president", the burning of the Hindenburg "Oh, the humanity!" and countless other snippets of history, all recorded on a 55. That's history for you. While Hitler whipped up the masses with a bank of Neumanns (the original voice of terrorism), our guys said it like it was into the forerunner of the SM57, the 55, a mic for working days.
Oh yeah, you'll find the standard thread on a mic stand has changed a tiny little bit over the years, and if you have original 55's, they may not match too well. I found that a mic stand adaptor and a little teflon plumber's tape helped out there. And I pray for your sake that that RCA is the real deal. If it is, I hope you like your new car.-Richie
