I just stumbled onto this forum doing a desperate googlesearch for info regarding these mics. The thread is less than a year old, so I'll add what little I know for the record.
I bought mine circa 1977 for $50 each, to use in conjunction with a Uher CR134 to record live music. I know I have used mine very little, but a friend used the same setup to record Charles Mingus. The recordings were great.
Each mic came with an individual frequency response chart. Inside is a little card which says in part:
"Why the Beyer Dynamic M550S Omnidirectional Microphone is the Best Value for Money:
The Beyer M550S features the well tried and proven moving coil principle, and is totally independent of power supply (not even a battery is needed).
Specification copnsistency: only the moving coil transducer can claim as little as +/- 3dB frequency response variation from one transducer to another.
Omnidirectional microphones hear sound evenly from all directions. They are less susceptible to handling and "P" popping noises, and generally feature a smoother, wider frequency response than cardiod and hypercardiod types. Ideal for tape recording, interview and television/film applications, omnidirectional microphones can also be effectively used live under equalized or acoustically good conditions."
The rest of the copy is mostly hype. The box lists 4 model variations: M 550 LM, LM S, N(K), and N(K)S. Mine are are LM S. The box is checkmarked 500 Ohm versus "other".
I just broke them out to prep my old Teac A2340 for sale on eBay. Although I'm using a seriously limitedtestbed, they sounded dandy to me. These are apparently pretty scarce; I only had one google hit for it, a recording studio. I stumbled here from a hit for a different Beyer, but am glad I did. I don't really do home recording, an aspiration in the dark past, but may once I get all my old gear liquidated
At least my first post here was a contribution of sorts rather than a plaintive newbie question.
