Valve vs. solid-state microphone preamplifier: a comparative study

Abstract

This paper outlines research carried out to determine the perceptual and objective differences between a solid-state and a valve preamplifier running at low voltages. ABX testing was employed and showed that there were perceivable differences between the two systems. A comprehensive objective analysis was performed, which utilised tests for total harmonic distortion + noise (THD+N), intermodulation distortion (IMD), THD versus frequency and frequency response in order to ensure the two systems were performing in their linear region. In addition, MIRToolbox was utilised to extract low-level features such as spectral centroid, skewness and novelty. The electronic measurements combined with the MIRToolbox support the listeners’ subjective descriptors that there is a difference in brightness and harmonic content between the two types of preamplifiers. A correlation theory was developed, which linked the objective and the subjective measurements