Review on 🎛️ Enhanced Precision with the Instruments R8090 Calibrator Diameter Microphones by Ryan Sandell

03/15/2019. The new device comes with a dead battery and the switch is on. Replace it with a new Duracell 9VDC battery and it will produce the correct frequency and dB. Before calibrating sound level devices, it is recommended to check the battery voltage to ensure proper operation and calibration.