The Crown Models PZM-30GPB, PZM-30D boundary or “Pressure Zone” microphones (1980)
This is a Crown PZM-30-GPB, courtesy of Jeff Rudisill. (The specifications below are for the PZM-30D.)
Hear the sound of the PZM-30GPB (as pictured).
Description The Crown PZM-30D is a Pressure Zone Microphone designed for professional recording, sound reinforcement and broadcasting. It has many applications, from miking full orchestras or individual musical instruments to security or teleconferencing.
The PZM-30D has a switchable dual frequency response: rising (R) or flat (F). The “rising” position adds brilliance. This makes it useful wherever a crisp attack is desired, such as on percussion, drums, or piano. The user can get a bright sound without boosting high frequencies on the recording console; the result is lower noise. The “flat” position provides a smooth, flat high-frequency response for natural sound reproduction.
These sturdy microphones are especially reliable because they can be used with a rugged detachable cable. The output is a male 3-pin XLR type, balanced and low impedance, which permits long cable runs without hum pickup or high-frequency loss.
Like other Pressure Zone Microphones, the PZM-30D utilizes the Pressure Recording Process in which a miniature condenser microphone capsule is mounted in the “Pressure Zone” just above the boundary, a region where sound coming directly from the sound source combines in phase with sound reflected off the boundary. The benefits are a wide, smooth frequency response free of phase interference, with excellent clarity and reach, a hemispherical polar pattern, and uncolored off-axis response.
Operating Instructions The PZM-30D features self-contained electronics which allows it to plug directly into a standard 12-48 VDC phantom power supply. Using two-conductor shielded microphone cable, plug the microphone into a phantom power supply. Connect the power supply output to a mixer mic input, or if your mixer has phantom power built in, simply plug the PZM directly into a mixer mic input.
Placement PZMs are designed to operate on any stiff non-absorbent boundary (or surface). Typical boundaries are a floor, wall, ceiling or table. This type of mounting improves the low-frequency response. The published response curve is measured on an “infinite” boundary such as a floor, ceiling or wall. The microphone’s low-frequency response depends on the size of the boundary upon which it is placed.
Regarding the silver-colored adapter plugged into the mic shown in the photo, an inquiry made to Crown brought the following response. Our thanks to Mr. Chapman for his time.