Something is certainly wrong. The pots themselves are not used in such a way that crackles and pops would be expected. You probably have a construction error somewhere that is allowing too much gain at one stage, causing it to clip. Make sure the diodes and 470R around pins 6-7 of IC6 (last TL074 multiplier stage) are correct, as they limit the gain.
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Re: CGS29 Wave Multiplier Noisy Pots
2014-04-27 by cg_synth