The GAD-201G distortion meter is aimed at total harmonic distortion (THD) and AC voltage measurement at audio frequency range, from 20 ~ 20kHz. Frequency and voltage value are displayed simultaneously on dual meters, with measurement range automatically switching over full scale. Shortcut keys are provided for commonly used 400Hz, 1kHz, and 10kHz measurement. Output terminal feeds basic waveform (X) and harmonic distortion (Y) to external monitoring device. Residual distortion, including hum and noise, is kept at a minimum level of 0.03% making GAD-201G ideal for high-class audio application.