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Endevco® model EM42AA pistonphone calibrator

Endevco® model EM42AA pistonphone calibrator
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Endevco® model EM42AA pistonphone calibrator - 1

The Endevco pistonphone model EM42AA is a batteryoperated, precision sound source for accurate and reliable calibration of measurement microphones, sound level meters and other sound measuring equipment. With a microphone placed in the coupler of the pistonphone, the calibration level is: • 114 dB 1 re. 20 ìPa • 105.4 dBA re. 20 ìPa (with A-weighting applied) At a static ambient pressure of 101.3 kPa, no further correction factors need be applied. The model EM42AA is an extremely stable laboratorystandard sound source which can also be used for field calibrations - it retains its high accuracy even under hostile environmental conditions. The model EM42AA is normally delivered for calibrating ½-inch microphones directly since these are most commonly used but can be delivered with a 1-inch coupler for calibrating 1-inch microphones directly if preferred. The pistonphone works on the principle of two reciprocating pistons actuated by a precision-machined cam with a sinusoidal profile. The rotation speed of the cam is controlled to within 0.5% via a tachometer signal in a feed-back loop. The model EM42AA has a dual-colour LED above the ON/OFF switch to indicate both battery condition and stable operation. When the pistonphone is operating properly, the LED shows green, indicating that the speed of the cam is correctly locked to give 250 Hz. If it shows red while the pistonphone is switched on, the speed is incorrect; most likely because of low batteries. The operating procedure is straight forward, simply fit the microphone into the coupler of the pistonphone and switch on. The pistonphone will now produce a constant sound pressure level on the diaphragm of the microphone. The pistonphone model EM42AA is compatible with Endevco ½-inch, ¼-inch and 1/8-inch microphones and all other microphones having the same standard diameters. Adapters are included for calibrating ¼-inch and 1/8-inch microphones. Typical applications • Reference calibration source • Precision microphone calibrations • Microphone comparisons • P-I index measurement at 250 Hz Endevco® model EM42AA Pistonphone Description cmyk

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Endevco® model EM42AA pistonphone calibrator - 2

Endevco® model EM42AA Pistonphone Specifications Sound pressure level: Nominal: 114 dB re. 20 ìPa Individually calibrated under the following reference conditions:- Ambient pressure: 101.3 kPa Ambient temperature: 20°C (68°F) Ambient humidity: 65% RH Calibration accuracy: Absolute: ±0.09 dB at reference conditions Frequency: 250 Hz ±0.5% Distortion: <1.5% Nominal effective coupler volume: 15540 mm3 Temperature range: Batteries permitting: –10°C to +55°C (14°F to 131°F) Batteries: Four standard LR6-AA alkaline cells Dimensions: Length: 175 mm (6.89 in) Width: 35 mm (1.38 in) Height: 35 mm...

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