ARCHITECT'S AND ENGINEER'S SPECIFICATIONS:

The microphone shall be of the dynamic moving coil type. Response shall be 80 Hz to 13 kHz, specially shaped above 1 kHz to maintain presence for vocal and musical pickups, and, below 1 kHz, shall vary inversely with distance. 100 Hz response with sound source 24" from the microphone shall be nominally 10 dB lower than response with sound source from microphone. Response at front of microphone at 1 kHz shall be nominally 20 dB greater than response at rear. The microphone shall be of the low impedance type, wired, and shall include a separate 25' cable with A3M- and A3F- type connectors. It shall have an output at 1 Pa of -61 dB. Themicrophone shall have a mylar diaphragm. An On/Off switch shall be provided, so connected that the transducer is "shorted" when switch is in "off" position. It shall include an internal pop filter, and internal shock mounting for the dynamic element. The case shall be constructed of steel and zinc die cast parts with a nonreflective grey finish. The overall length of the microphone shall not exceed 6.63" (16.8 cm) and the maximum diameter shall not exceed 2.16" (55 cm). The weight shall not exceed 8.9 oz (252 g).
The microphone shall be the Altec Lansing D658.