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Audio myth debunked

acoustic effects study

Study on the acoustic effects of aluminum electrolytic capacitors from Würth Elektronik

With Application Note ANP125 “The acoustic effects of harmonic distortions of aluminum electrolytic capacitors”, Würth Elektronik publishes the results of a study on the total harmonic distortion of commercially available electrolytic capacitors. The result: the capacitors do not cause any significant distortion of the signals.

There is an ongoing debate in audio technology around the sound quality of amplifiers and the perceptibility of signal distortions. The suspicion that capacitors are a source or contributor to high-frequency distortions that influence auditory perception can now be considered unfounded in view of the study carried out.

Application Note ANP125 is the result of an international research collaboration between the R&D teams at the production sites in Asia and the Würth Elektronik Competence Center in Berlin. The text begins with an introduction to human hearing and psychoacoustics before moving on to analyze harmonic distortions in capacitors. Furthermore, the results of the model calculations are presented to check the plausibility of the measured results. Measurements show that there are no significant signal distortions due to the capacitors.

Also investigations with material variations

'Research indicates that material variations have a negligible influence on distortions and that these distortions are below the hearing threshold. Electrolytic capacitors do not add significant harmonics to fundamental frequencies when transmitting signals and can therefore be considered fairly roughly linear components. Other types of capacitors and voltage-independent passive components are likely to generally produce similarly low distortion amplitudes compared to the audibility threshold,” explains Dr. René Kalbitz, Product Manager in the Capacitors and Resistors division at Würth Elektronik. eiSos and author of the study. "Consequently, the choice of non-linear components such as operational amplifiers and diodes has a greater impact on the distortion-driven audio quality of the amplifier, that is, on the total distortion characteristics, than the choice of electrolytic capacitor." .