Neumann promoted the supposedly flat frequency response of the KM 84, but that is true only by comparison with their previous small cardioid (the KM 54) and within the bounds of their usual tolerance limits. The microphone definitely had a low-frequency rolloff and some high-frequency emphasis, and prior to Catalog 100 (1977) the company was quite open about this. For example, the attached response curves are from the 1968 "fet 80" catalog.
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