RCA 10001C (Years Unknown)

Little is documented about the RCA 10001C. Period reference material identifies it as the RCA MI-10001C ribbon-velocity unidirectional microphone. The surviving catalog entry gives the full designation with the "MI-" prefix, and that entry is about the fullest record of the model found so far. Audio-Collection (undated, pp.168-170) reproduces horizontal polar patterns for the 200-800 Hz range and frequency-response curves for both zero-degree and 45-degree sound incidence.

The same reference work also covers ribbon-velocity microphones, the type the 10001C belongs to. Low-frequency response rises as the microphone gets closer to the source. For dialogue pickup, the response below 200 Hz generally has to be rolled off, either by a voice filter built into the microphone or by an external dialogue equalizer. Otherwise the low end gets heavy and tubby. It also advises keeping a ribbon-velocity microphone at least four feet from the source unless that rolloff is engaged. Those are period operating notes for the type, not verified measurements of this particular unit.

No production years, original price, full specification sheet, or market history have surfaced in the available documentation.