A comparative study of frequency response and total harmonic distortion (THD) in live-sound mixing console preamplifiers: Technical evaluation and genre-matching implications

Abstract

In music production, sound quality is greatly influenced by the performance of microphone preamplifiers, which determine tonal transparency and harmonic integrity at the earliest stages of the signal chain. Therefore, analyzing and examining how different console architectures affect measurable fidelity is important for both professional sound engineers and educational institutions. The objective of this study was to compare the frequency response and total harmonic distortion (THD) characteristics of preamplifiers integrated into six professional live sound mixing consoles (Soundcraft Vi7000, DiGiCo Quantum 225, Yamaha CL5, Midas M32, Midas PRO1, and Allen & Heath iDR32) under identical test conditions. The research was conducted using a quantitative quasi-experimental model in which the mixing consoles themselves represent non-manipulable instruments with characteristics that cannot be experimentally manipulated. The preamplifier of each console was treated as an experimental subject. A 20 Hz–20 kHz logarithmic sine sweep signal (1 M samples, 0 dBFS, 48 kHz, 32-bit PCM) was used as the measurement stimulus. Data were collected at five gain points (+0 dBFS, +6 dBFS, +12 dBFS, +18 dBFS, +24 dBFS), and the results were analyzed in Room EQ Wizard (REW) to determine amplitude deviation (± dBFS) and % THD. The results showed that all consoles maintained nearly flat responses within the audible range, with deviations at the spectral margins. Following a targeted literature review on genre-specific production spectra, the measured response and distortion profiles were mapped to representative musical genres to evaluate potential genre–preamplifier affinity. To triangulate these inferences, a controlled listening test with 60 participants was conducted, assessing perceived performance across consoles under blinded conditions. The listening test largely aligned with measurement-based findings, with stronger agreement among trained listeners than non-trained listeners.

Keywords

• live sound mixing console
• preamp
• audio measurement
• frequency response
• total harmonic distortion

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