The Distortion Analyser KM 6 is a multi-purpose instrument for low frequency measurements in the laboratory, the test line, for educational purposes and for use in the hi-fi service department. Designed for total harmonic distortion measurements in the range 0.01% to 100% over a frequency spectrum of 10 Hz to 100 kHz, the precision distortion factor meter is equipped with a variable active filter for the fundamental frequency. The alignment to the 100% reference level as well as frequency and balance alignment take place semi-automatically. Rapid and accurate measurements are ensured through 12 light-emitting diodes which indicate the alignment conditions of the 100% reference stage, the automatic frequency and balance circuit and which also indicate the meter range selected. The unit contains a sensitive AF-voltmeter for the voltage range 300 m-V ... 300 V (f. s. d.). It can also be used as a frequency meter over the range 10 Hz ... 100 kHz. The unit is equipped with silicon semi-conductors and integrated circuits. In addition to a standard bench-top version with a tilting frame, the unit is also available in a special version for mounting into 19 inch racks.