Preamplifiers Rion NH-22A

Description

A preamplifier with high input impedance and low output impedance is required in order to faithfully transfer the voltage converted by the microphone to the subsequent amplifier. In the Preamplifier, the electrical circuit and 7-pin connector shown in Fig, 2 have a unified structure and various models are available to ensure the optimal combination for the type of microphone and diameter. A conversion adapter is used when using a microphone with a different diameter.   

Characteristics and usage

Preamplifiers are connected to microphones with a high input impedance and generate output signals with a low impedance. In measurements using a long extension cable, the maximum output voltage, which is affected by the length of the cable, changes, thereby changing the sound pressure level by frequency that can be measured. This is due to the change in electrostatic capacitance between the signal line and shield as a result of the cable length, as illustrated in Fig. 3.

For example, the extension cable can be no longer than about 50m when meauring sound pressure of 110dB to 10 kHz using a microphone with a sensitivity level of -26 dB (Model UC-27). Fig.4 indicates the relationship between the output impedance of the preamplifier and the maximum measurement frequency determined by electrostatic capacitance of the preamplifier and the maximum measurement frequency determined by electrostatic capacitance based on the length of the extension cable. Since the output impedance of the preamplifier is 100 Ω or less, frequency response can readily be handled to 15 kHz even if using an extension cable with a length of 500m

Specification