MEGGn smart engineering for extrme environments Endevco® model EM40AD V" Prepolarized pressure microphone Typical applications Prꕩcision acoustic measurements Coupler measurements Օ Flush (boundary) measurements Use with Endevco Isotron® preamplifiers Օ Repairable Description The Endevco microphone model EM40AD is a VV-inch precision condenser microphone for general purpose acoustic measurements, e.g. in couplers, boundaries and m enclosures; it can also be used as a random-incidence microphone. It is a prepolarized pressure microphone with a large dynamic range and a wide frequency response. As a pressure microphone, the model EM40AD measures the sound pressure at the location of its diaphragm. It has a flat pressure-frequency response over its entire working frequency range (see Fig.1). In an open sound field, a pressure microphone will also include the disturbing effects of its presence in the sound field. These are minimal at low frequencies (large wavelengths compared with microphone size). At higher frequencies the effects of reflections and diffractions must be accounted for Generally, they lead to an increase in the measured sound pressure and corrections have to be made. Fig.2 shows what these corrections are in a free field for various angles of incidence. Endevco Isotron® preamplifiers are also available for use with the model EM40AD, these are: VV-inch preamplifier model EM26CA 'A-inch preamplifier model EM26CB with adaptor All Endevco microphones comply with the specifications of IEC 1094: Measurement Microphones, Part 4: Spcifications for working standard microphones. Non-corrosive, stainless materials are used in manufacturing these microphones to enable them to withstand rough handling and corrosive environments. All Endevco microphones are guaranteed for 5 years and are individually checked and calibrated before leaving the factory. An individual calibration chart is supplied with each microphone.

Endevco® model EM40AD Vi" Prepolarized pressure microphone Spcifications MEGG NT smart engineering for extrme environments Frequency response: 3.15 Hz-10 kHz: 12.5 Hz-7.5 kHz: Nominal sensitivity: at250 Hz: Polarization voltage: Upper limit of dynamic range: 3% distortion: Lower limit of dynamic range: Thermal noise: Capacitance: Polarized: Temperature range: Temperature coefficient (250 Hz): -10°C to +50°C: Static-pressure coefficient: 250 Hz/25°C: Humidity range: Influence of humidity (250 Hz): Influence of axial vibration, 1 m/s2: Venting: IEC 1094-4 type designation: Dimensions (with protection...