The Agilent-Hp 334A Distortion Analyzer covers 5Hz to 600kHz frequency range. The unit measures down to 0.1% full-scale distortion, residual noise measurement below 25 V, and voltages over a wide range, 300 V to 300 V rms full scale. Some of the features include an Auto Nulling feature, which speeds up the time consuming portion of measurements, an AM Detector, which has a frequency range from 550kHz to 65MHz and a 1kHz High-Pass Filter, which attenuates frequencies below 400Hz, reducing the effect of hum components.