Bruel and Kjaer
Type 8106 features a built-in amplifier that provides a signal necessary for transmission over long range cables. It can be used below 1000 m ocean depths.
It is a wide-range, regular-purpose transducer for developing absolute sound calibrations over the frequency range 7Hz to 80 kHz with an incoming sensitivity of ?173dB re 1V/?Pa. The hydrophone is able to withstand high static pressure, the operational upper limit being 107 Pa (100 atm.; 1000 m (3250 ft.) ocean depth). Also featuring a built-in good-quality, thick-film, low-noise, 10 dB preamplifier which provides signal regulating for transmission to long underwater cables. The preamplifier comprises of a 7Hz high-pass filter with an insert-voltage measurement facility. However, it does not let the hydrophone to be utilized as a projector. A combined watertight linker lets fast detachment of the cable making the replacement and storage easier.