Used to convert high impedance signal from measurement microphone into low impedance signal, Model 426A13 is designed for ½ in. microphones used to measure frequencies within both infrasound and the human audible range (3 Hz to 20 kHz). Preamplifier electronics fit in 0.94 in. long housing, and overall length (including connectors) of 1.4 in. accommodates space-constrained test environments. Noise floor allows measurements from 15 dBA to 147 dB with appropriate microphone.