Frequency response and THD comparison of live sound mixing preamps with practical 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

• audio measurement
• frequency response
• live sound reinforcement
• microphone preamplifiers
• mixing consoles
• music technology
• psychoacoustics
• Total Harmonic Distortion (THD)

Ethical Statement

Ethical approval for this research was obtained from Ankara Music and Fine Arts University (Approval Document No. 109210). The study was conducted in accordance with the relevant institutional regulations and ethical principles governing scientific research. All procedures involving participants were designed to minimize potential risk and burden, and participation was based on voluntary informed consent. Prior to data collection, participants were informed about the purpose and scope of the study, the procedures to be applied, and their rights to refuse participation or withdraw from the study at any stage without any negative consequences. Confidentiality and privacy were ensured throughout the research process. Personal Low frequency response identifiers were not recorded in the dataset, and all data were handled and reported in an anonymized form. Access to the research materials was restricted to the research team, and the collected data were stored securely and used solely for scientific purposes within the scope of the approved protocol. Any dissemination of findings was carried out in a manner that prevents the identification of individual participants. The authors declare that there are no conflicts of interest relevant to the content of this study. No commercial entity, manufacturer, or distributor of the mixing consoles examined in this research provided funding, equipment, sponsorship, or any form of material or non-material support. All analyses, interpretations, and conclusions were developed independently, and no external party influenced the research design, data collection, measurement procedures, or reporting process.

Thanks

Ankara Music and Fine Art University

References

1. AES-6id-2006 (s2017). (2017). https://www. aes.org/publications/standards/search. cfm?docID=6 Canyakan, S. (2017). Ses Tarihi: Audio Özelinde Müzik Teknolojisi ve Kökeni. Uşak Üniversitesi Sosyal Bilimler Dergisi, 10(2). https://doi.org/10.12780/ usaksosbil.373860
2. Czedik-Eysenberg, I., Knauf, D., & Reuter, C. (2017). “Hardness” as a semantic audio descriptor for music using automatic feature extraction. Lecture Notes in Informatics (LNI) - Proceedings, P-275. https://doi. org/10.18420/IN2017_06
3. Eargle, J. M. (2002). Electroacoustical Reference Data. Springer US. https://doi. org/10.1007/978-1-4615-2027-6 Everest, F. A., & Pohlmann, K. C. (2022). Master Handbook of Acoustics (7th Edition). McGraw-Hill Education. https://www. accessengineeringlibrary.com/content/ book/9781260473599
4. Farina, A. (2000, February 1). Simultaneous Measurement of Impulse Response and Distortion with a Swept-Sine Technique. Audio Engineering Society Convention 108. https://www.aes.org/e-lib/browse. cfm?elib=10211
5. Fastl, H., & Zwicker, E. (2007). Psychoacoustics. Springer. https://doi. org/10.1007/978-3-540-68888-4
6. Fink, D., & Bortoni, R. (2022). Analog and Digital Gain in Microphone Preamplifier Design. Audio Engineering Society Conference: 50th International Conference: Audio Education. https://www.aes.org/e- lib/download.cfm/21896.pdf?ID=21896
7. Gaskell, R.-E. (2013). A Simple Microphone Preamplifier Design to Support the Teaching of Introductory Electronics to Students of Audio. Audio Engineering Society Conference: 50th International Conference: Audio Education. https://www.aes.org/e- lib/download.cfm?ID=16861
8. Gaskell, R.-E. (2016). Subjective and Objective Evaluation of Distortion in Analogue Electronics: Capacitors and Operational Amplifiers. Doctorate Thesis. McGill University. https://bac-lac. on.worldcat.org/oclc/953107637? lang=en

9. Hebert, G. K. (2014). DC Servos and Digitally- Controlled Microphone Preamplifiers. Journal of the Audio Engineering Society, 137. https://www.thatcorp.com/datashts/ AES9198_DC_Servos_and_Digitally- Controlled_Microphone_Preamplifiers.pdf
10. IEC 60268-5:2003+AMD1:2007 CSV. (2007). https://webstore.iec.ch/en/ publication/1222
11. Kirchberger, M., & Russo, F. A. (2016). Dynamic Range Across Music Genres and the Perception of Dynamic Compression in Hearing-Impaired Listeners. Trends in Hearing, 20, 2331216516630549. https:// doi.org/10.1177/2331216516630549
12. Kok, C. L., Chia, K. J., & Siek, L. (2024). A 87 dB SNR and THD+N 0.03% HiFi Grade Audio Preamplifier.Electronics,13(1),118.https:// doi.org/10.3390/electronics13010118
13. Pestana, P. D., Ma, Z., Reiss, J. D., Barbosa, A., & Black, D. A. A. (2013). Spectral characteristics of popular commercial recordings 1950-2010. 135th AES Convention. 135th International AES Convention, New York. https://aes2.org/publications/ elibrary-page/?id=17010
14. Reiss, J. D. (with McPherson, A. P.). (2015).
15. Audio effects: Theory, implementation and application. CRC Press.
16. Rumsey, F., & McCormick, T. (2009). Sound and Recording. Focal Press.
17. Shadish, W. R., Cook, T. D., & Campbell, D. T. (2002). Experimental and quasi- experimental designs for generalized causal inference (pp. xxi, 623). Houghton, Mifflin and Company. https://iaes.cgiar.org/sites/ default/files/pdf/147.pdf
18. Shmilovitz, D. (2005). On the definition of total harmonic distortion and its effect on measurement interpretation. IEEE Transactions on Power Delivery, 20(1), 526–528. https://doi.org/10.1109/ TPWRD.2004.839744
19. Stuart, J. (1994). High quality audio- (outline). IEE Colloquium on Audio Engineering, 3(1). https://ieeexplore.ieee. org/document/297484
20. Temme, S., Brunet, P., & Qarabaqi, P. (2013).
21. Measurement of Harmonic Distortion Audibility Using a Simplified Psychoacoustic Model—Updated. 22. https://aes2.org/ publications/elibrary-page/?id=16885
22. Toole, F. (2008). Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms. doi. org/10.4324/9781315686424
23. Winer, E., & Lawrence, M. (2025). The Audio Expert: Everything You Need to Know About Audio (3rd ed.). Focal Press. https://doi. org/10.4324/9781003518242