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The Crown Models PZM-30GPB, PZM-30D
boundary or “Pressure Zone” microphones (1980)

The Crown PZM-30GPB
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).

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.

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.

Note from Crown

The PX-T schematic

PZM-30GP data sheet
Download for the PZM-30GP, PX-18, PX-T
and several others (1.7-megabyte PDF)

Crown PZM30D data sheet
Download the Data Sheet for the PZM-30D.


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