Traditional measurement microphones often required high voltage 200V power supplies. The high voltages were required to polarize/charge the diaphragms, and originally to operate tubes that comprised the preamp circuitry. However since electret microphone elements are precharged diaphragms, and modern circuitry is semiconductor solid state, high voltages are not required and the Low Voltage Power (LVP) interface was created. This interface is simple to power and eliminates the special cables, connectors, potential shock/safety issues, and higher cost of the old high voltage systems.

The LVP interface uses a simple 3 wire unbalanced direct power configuration: 1-COM, 2:SIG, 3:+9VDC. This enables common low cost microphone cables and standard 3-Pin XLR connectors to be used. Both the signal and power are handled by separate wires/pins, which enable response down to 0Hz. This is not practical with other phantom power or ICP powered systems where the signal and power are mixed together on the same lines. The LVP interface provides much greater power and flexibility than phantom power or ICP powered systems, and can be used to operate microphones, accelerometers, and complex preamp circuitry demanding up to 50mA or more.

The microphone/transducer inputs on all of our analyzers provide the LVP interface. If you intend to use our transducers with other equipment that does not directly power the LVP interface, you will need to create your own custom cables and power source. This is very easy to do and is described in the PDF document below.

If you wish to incorporate the LVP interface into other equipment circuitry, the 9VDC supply can often be produced from some other internal existing higher voltage such as 12V, 15V, 18V, 24V, etc. using a common 78L09 linear regulator IC.