Dupont AC-1 Acoustical Calibrator

AMETEK AC-1 Acoustical Calibrator

Du Pont Company Operating Manual Acoustical Calibrator Model AC-1 1982

DT-805 Professional Sound Level Meter Industrial Noise Decibel Tester Noisemeter

General Radio Permissible Sound-Level Calibrator Type 1562-A w/ Case

CEL Instruments CEL-284 Acoustic Calibrator 114 dB 1kHz + Electrical O

Nicholson Scott Instrument Laboratories Type 452 Sound Level Meter Calibrator 45

QUEST Electronics CA-12B Sound Calibrator 110 dB-1000 Hz