Here is a vintage 1940s RCA Type 44-B velocity ribbon microphone. This particular example, serial number 1087, is in very excellent condition and was completely serviced several years ago. Since then, it has been properly stored in a professional studio and has been used extremely infrequently. Both accessible and very serious, the RCA 44-BX ribbon microphone is considered by engineers and audiophiles to be amongst the absolute best.
The Type 44-B Velocity Microphones (MI-3027-A, -B, -C, and -D) are high-fidelity microphones of the ribbon type that are specially designed for broadcast studio use. They are constructed to withstand mechanical shocks, and to retain sensitivity and frequency response regardless of changes in temperature, humidity, and barometric pressure. Their essentially flat frequency response (50 to 15,000 cycles) is suitable for reproducing both voice and music. One of the most useful properties of a velocity microphone is its bi-directional or figure-eight directional characteristics. The output of the microphone is maximum for sounds originating directly in front of or behind the micro phone, and minimum for sounds originating at the sides, top or bottom. This characteristic is valuable for both vocal and musical pickup. For vocal pickup, its chief value lies in the fact that it enables participants in dialog to face each other across the microphone. For musical pickup, it makes it possible to obtain different effects by arranging orchestral instruments about the microphone so that the sounds of some instruments are attenuated and others are accentuated. The frequency response of a velocity microphone is essentially uniform when the sound source is at least three feet from the microphone, but the low frequencies are accentuated when the sound source is closer to the microphone. Speakers and singers are often required to stand close to the micro phone, and the low-frequency accentuation which occurs is undesirable except when special effects are wanted. To solve this problem, a jumper connection is provided on the microphone terminal board that provides either of two degrees of compensation for close talking. When the jumper is in the M (music) position no compensation is provided, and the response is essentially uniform from 50 to 15,000 cycles per second, provided that the announcer or musical instrument is at least three feet from the microphone. However, the announcer may move as close to the microphone as 12 inches when the jumper is in the V1 position, or seven inches when it is in the V2 position, without causing objectionable low-frequency boost. (V1 -5dB shelf at 100hz, V2 -10dB shelf at 100hz) This particular example has been modified with a standard XLR microphone cable.