A critical investigation into the properties of metallised film capacitors for high quality sound reproduction

Dodds, PS

Abstract

This is an account of work carried out through a Knowledge Transfer Partnership with
Industrial Capacitors (Wrexham) Ltd to assess the effects of metallised film
polypropylene capacitors on key sonic attributes of reproduced sound. The capacitors
under investigation were found to be electrically identical whilst exhibiting differing
levels of mechanical resonance within the audio frequency band. Results obtained
from subjective listening tests have shown this to have a measurable effect on audio
delivery.
The listening test methodology employed in this study evolved from initial ABX type
tests with set program material to the final A/B tests where trained test subjects used
program material that they were familiar with. The main findings are that capacitors
used in crossover circuitry can exhibit mechanical resonance and that maximizing the
listener's control over the listening situation and minimizing stress to the listener were
necessary to obtain meaningful subjective test results.
The main findings are that capacitors used in crossover circuitry can exhibit
mechanical resonance and this resonance was identified to have a negative effect on
reproduced sound in controlled subjective listening tests. In addition, new
measurement techniques have been developed that could be used to identify low
resonance capacitors during production and, hence, select capacitors that were likely
to have superior reproduction quality without the need for further listening tests.

Citation

Dodds, P. A critical investigation into the properties of metallised film capacitors for high quality sound reproduction. (Dissertation). University of Salford

• Thesis Type: Dissertation
• Deposit Date: Aug 17, 2021
• Award Date: Jan 1, 2009