A volume pedal equipped with a precise magnetic sensor enabling it to operate almost wear-free. This sensor uses the Hall effect, named after Edwin Hall, to measure the strength of magnetic fields. In the Lehle Mono Volume 90, the Hall sensor, which is made in Germany, is accurately calibrated to the built-in magnet and the control range of the pedal. A premium Blackmer VCA (= Voltage Controlled Amplifier) from the United States replaces the mechanical potentiometer. The principle of the voltage-controlled amplifier is based on the fact that gain can be varied by the control voltage coming from the Hall sensor. Over the entire control range the Lehle Mono Volume 90 transmits the full sound spectrum of the connected instrument. Internally, the input voltage coming from the power supply socket of the pedal is rectified, then filtered, stabilized and doubled to 18V, thus achieving a total dynamic range of 110 dB. The volume control of the Lehle Mono Volume 90 ranges from -92 dB to 0 dB - so from a virtually muted level to the same volume.