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¼-inch Pressure Microphone Type 40BP0 pages
!/4-inch Pressure Microphone Type 40BP Product Data and Spcifications Typicat applications m Sound pressure measurements m High frequency measurements m High level pressure measurements The G.R.A.S. Microphone Type40BP is a W-inch prcision condenser microphone for g驪nerai pur-pose acoustic measurements, c.g. in couplcrs and al boundaries. II is an exlernally polarized pressure microphone wilh a large dynamic range and a wide frequency response. As a pressure microphone, ihe Type 40BP measures the sound pressure al Ihe location of ils diaphragm. It has a flat pressure-frequency response over ils entire woiicing frequency range (see Fig. 2). In an open sound field, a pressure microphone will also include the disturbing effects of its prsence in ihe sound field, Thse are minimal for most of its frequency range because of its small dimensions (sce Fig. 1 inset). At higher frcqucncics, the effects of reflections and diffractions must be accounted for Gcnerally. they lead to an increase in the measured sound pressure and collections have to bc inade. Fig* 3 shows what th騨se corrections are in a free licld for various angles of incidence. G.R.A.S. W-inch preamphfiers (see data sheet for Types 26AA, 26AB, 26AC and 26AL) are also Fig, I Yj-inch Pressure Microphone Type 40BP (inset shows tme size) available for use with the Type 40BR Ihe mount-ing thread (5.7 mm - 60 UNS-2) is compatible with other available makes of smilar microphone preamphfiers. Ail G.R.A.S. microphones comply with Ihe spcifications of IEC 1094: Measurement Microphones, Part 4: Spͩcifications for working standard microphones. Non-corrosive, stainless inaterials are used in manu-facturing thͨse microphones lo cnablc them to with-stand rough handling and coirosivc environments. Ali G.R. A.S. microphones are guaranteed for 5 years and arc individually chcckcd and calibratcd beforc leavng the facloiy An individual calibration chart is supplied with each microphone. Spcifications Frequeocy respoDsc: Upper limil (3 % distorton): 4Hz- 70kHz *2.0dB 174dB re. 20[iPa 10Hz-25kHz............ ..........±1.0 dI3 Microphone llu i ni.il mus.: Nominal sensltivily: 31dBAre. 20nPa 1.6mV/Pa Ciipaci lance: Polaii/alion voilage: 7pF 200V .continued overlcaf G.R.A.S. Sound & Vibration Skovlytoften 33 2840IIoltc. Dcnmark Tel +45 45 66 40 46 Fax +45 45 66 40 47 e-mail: gras@gras.dk www.gras.dk
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