Low distortion circuit is very important if we want to measure distortion level of an audio equipment, but this is just one example of low distortion oscillator circuit application. Here is the schematic diagram:

Low Distortion Oscillator circuit schematic

This oscillator is designed for audio application, with the adjustable frequency range of 30Hz to 20kHz, set by 470k pot. This potentiometer should be of stereo type, where the wiper of both resistive tracks is tied into a single axis.  The 22k pot is provided to adjust the distortion level, try your best to adjust this knob for getting the lowest distortion level. [Circuit's schematic diagram source: lh-electric.4t.com]