The funny thing is that most of these hyper-expensive vintage microphones would actually be rather bad by modern standards for live stereo recording at moderate distances like most of us do.
Probably the biggest exception would be the Neumann M 49 and M 50--but for typical miking distances for modern stereo recording you'd still need to bring down the M 50's high-frequency response a few dB. It's a fully diffuse-field-equalized omni, like a KM 130 or KM 183 is today (or the Schoeps MK 3 capsule which just about nobody buys any more).
Have a listen some time to some of the early stereo Mercury "Living Presence" orchestral recordings that were made with U 47s--the sound of the violins can almost cut glass, it's so sharp-edged. Really just about unlistenable.
Back when the U 47 was current it was considered too harsh for very close vocal miking--the main thing it gets used for today. People seem to need a little extra something to "cut through a mix." Back in the day, the whole idea of needing to "cut through" anything with vocal sound would be inconceivable and downright embarrassing and unprofessional; the arranger's job was to make sure that the voice fell right into place with no instruments competing or interfering with it.
Topic: What is the most expensive microphone out there? (Read 23549 times)