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Delivery: <= 7 days. True-PDF full-copy in English will be manually translated and delivered via email. GB/T 14475-2024: Horn loudspeakers - Measuring methods Status: Valid GB/T 14475: Historical versions
Basic dataStandard ID: GB/T 14475-2024 (GB/T14475-2024)Description (Translated English): Horn loudspeakers - Measuring methods Sector / Industry: National Standard (Recommended) Classification of Chinese Standard: M72 Classification of International Standard: 33.160.99 Word Count Estimation: 48,428 Date of Issue: 2024-10-26 Date of Implementation: 2025-05-01 Older Standard (superseded by this standard): GB/T 14475-1993 Issuing agency(ies): State Administration for Market Regulation, China National Standardization Administration GB/T 14475-2024: Horn loudspeakers - Measuring methods---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT14475-2024ICS 33.160.99 CCSM72 National Standard of the People's Republic of China Replaces GB/T 14475-1993 Horn Loudspeaker Measurement Methods Released on October 26, 2024 Implementation on May 1, 2025 State Administration for Market Regulation The National Standardization Administration issued Table of ContentsPreface V 1 Scope 1 2 Normative references 1 3 Terms and Definitions 1 4 Measurement signal 2 4.1 Overview 2 4.2 Sinusoidal Signal 2 4.3 Broadband Noise Signal 2 4.4 Narrowband Noise Signal 2 4.5 Pulse Signal 2 5 Acoustic Environment 3 5.1 Overview 3 5.2 Free field conditions 3 5.3 Diffusion field conditions 3 5.4 Simulating free-field conditions 3 6 Unwanted acoustic and electrical noise 3 7 Positions of horn loudspeaker and measurement microphone 3 7.1 Measuring distance under free field conditions 3 7.2 Position of horn loudspeaker under diffuse field conditions 4 7.3 Position of horn loudspeaker and microphone under simulated free-field conditions 4 8 Measuring equipment 4 9 Accuracy of acoustic measurements 4 10 Horn Loudspeaker Installation 4 11 Preload Processing 5 12 Polarity Mark 5 12.1 Feature Explanation 5 12.2 Test Method 5 13 Reference planes, reference points, and reference axes 5 13.1 Reference surface 5 13.2 Reference Point 5 13.3 Reference axis 5 14 Passive horn loudspeaker (without matching transformer) 5 14.1 Measurement conditions 5 14.2 Impedance 6 14.3 Input Voltage 7 14.4 Input power 9 14.5 Rated frequency range 9 14.6 Sound pressure in free field conditions 10 14.7 Response under free-field conditions 11 14.8 Output power (sound power) 13 14.9 Directional Characteristics 15 14.10 Amplitude Nonlinearity 17 15 Passive horn loudspeaker (with matching transformer) 21 15.1 Measurement conditions 21 15.2 Matching Impedance 22 15.3 Input Voltage 23 15.4 Input power 25 15.5 Rated frequency range 25 15.6 Sound pressure in free field conditions 25 15.7 Response under free-field conditions 25 15.8 Output power (sound power) 26 15.9 Directional Characteristics 26 15.10 Amplitude Nonlinearity 26 16 Active Horn Loudspeaker 27 16.1 Measurement conditions 27 16.2 Input Voltage 28 16.3 Rated frequency range 30 16.4 Sound pressure in free field conditions 30 16.5 Response under free-field conditions 31 16.6 Output power (sound power) 31 16.7 Directional Characteristics 32 16.8 Amplitude Nonlinearity 33 17 Stray magnetic field 35 17.1 Static Component 35 17.2 Dynamic Component 36 18 Size and Quality 36 18.1 Dimensional Measurement 36 18.2 Quality Measurement 36 Appendix A (Normative) Listening Test 37 A.1 Listening test for normal operation 37 A.2 Listening test for abnormal sound 37 Appendix B (Normative) Insulation and Environmental Adaptability 38 B.1 Insulation resistance 38 B.2 Withstand voltage 38 B.3 Vibration (sinusoidal) 38 B.4 Collision 38 B.5 Drop 38 B.6 High temperature loads and storage 39 B.7 Steady-state damp heat 39 B.8 Low temperature loads and storage 39 B.9 Dust and Waterproof 39 B.10 Salt spray 39 B.11 Solar Radiation 39 Reference 41 Preface This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1.Structure and drafting rules for standardization documents" Drafting. This document replaces GB/T 14475-1993 "Methods of measurement of horn loudspeakers". Compared with GB/T 14475-1993, except for the structural adjustment Besides the editorial changes, the main technical changes are as follows. a) The scope of application is limited to the performance measurement of electric horn loudspeakers for civil public broadcasting terminals (see Chapter 1,.1993 edition) Chapter 1); b) Added a chapter on “Terms and Definitions” (see Chapter 3); c) Added the measurement method of "transfer function" (see 14.7.3); d) Added "sound power within the frequency band" (see 14.8.1), "average sound power within the specified frequency band" (see 14.8.2), "specified frequency point" Measurement method of "power compression value" (see 14.8.5) and "power compression frequency response curve" (see 14.8.6); e) Added the measurement method of “coverage angle” (see 14.9.4); f) Added "characteristic harmonic distortion" (see 14.10.3), "nth order modulation distortion" (see 14.10.4), "nth order characteristic modulation distortion" (see 14.10.5) Measurement method of “secondary difference frequency distortion” (see 14.10.6); g) Added the measurement method for “passive horn loudspeaker (with matching transformer)” (see Chapter 15); h) Added the measurement method for “active horn loudspeakers” (see Chapter 16); i) Added the measurement method of “stray magnetic field” (see Chapter 17); j) Added the measurement method of “size and mass” (see Chapter 18); k) Added the test methods of “Listening Test” (see Appendix A) and “Insulation and Environmental Adaptability” (see Appendix B). Please note that some of the contents of this document may involve patents. The issuing organization of this document does not assume the responsibility for identifying patents. This document is proposed by the Ministry of Industry and Information Technology of the People's Republic of China. This document is under the jurisdiction of the National Technical Committee for Standardization of Audio, Video and Multimedia Systems and Equipment (SAC/TC242). This document was drafted by. Jiangsu Electronic Information Product Quality Supervision and Inspection Institute, Taixing Yangsheng Electronics Co., Ltd., Nanjing University Shenzhen Research Institute, Wuxi Jeff Electroacoustic Co., Ltd., China Electronics Technology Standardization Institute, and Hangzhou Cheling Network Technology Co., Ltd. The main drafters of this document are. Zhang Zhiqiang, Chen Jiasheng, Shen Dongbo, Shen Yong, Zhang Tengbiao, Yin Xiaogen, Cai Lujun, and Bao Sen. The previous versions of this document and the documents it replaces are as follows. ---First published in.1993 as GB/T 14475-1993. ---This is the first revision. Horn Loudspeaker Measurement Methods 1 Scope This document describes the methods for measuring the performance of horn loudspeakers for civilian-type public address terminals. This document applies to the measurement of electric horn loudspeakers for civil public broadcasting terminals. Horn loudspeakers for special purposes and other transducers It is used as a reference for measuring the principle of horn loudspeakers. Note 1.The "horn loudspeaker" mentioned in this document refers to the combination of a horn loudspeaker drive unit and a horn. The drive unit or horn may be one or more. It can also have a built-in transformer or a built-in amplifier. NOTE 2 The measurement methods given in this document are appropriately selected to reflect the characteristics of horn loudspeakers. 2 Normative references The contents of the following documents constitute the essential clauses of this document through normative references in this document. For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to This document. GB/T 2423.18-2021 Environmental testing Part 2.Test methods Test Kb. Salt spray, alternating (sodium chloride solution) GB/T 2423.24-2022 Environmental testing Part 2.Test methods Test S. Simulated solar radiation on the ground and solar radiation Guidelines for radiation tests and weathering tests GB/T 3241 Electroacoustic octave and fractional octave filters GB/T 3769 Electroacoustics - Scales and dimensions for plotting frequency characteristics and polar coordinate diagrams GB/T 3785.1 Electroacoustic sound level meters Part 1.Specification GB/T 4208 Degrees of protection provided by enclosures (IP code) GB/T 6881 Acoustics - Determination of sound power level and sound energy level of noise sources by sound pressure method - Reverberation chamber precision method GB/T 6882 Acoustics - Determination of sound power level and sound energy level of noise sources by sound pressure method - Anechoic chamber and semi-anechoic chamber precision method GB/T 12060.1 Sound system equipment Part 1.Overview GB/T 12060.3 Sound system equipment Part 3.Measurement methods for audio amplifiers 3 Terms and Definitions The following terms and definitions apply to this document. 3.1 drive unit driverunit An electrodynamic loudspeaker unit that provides a horn-driven sound source. Note 1.The drive unit is divided into compression drive unit and non-compression drive unit. The drive unit that matches the electromagnetic damping force resistance and the equivalent force resistance of the horn is called a compression drive unit; the uncompressed electromagnetic damping force resistance is usually greater than 1. The dynamic speaker unit is called a non-compression drive unit. Note 2.The frequency response characteristics of the compression driver are usually measured in a plane wave tube. The standing wave ratio generated by one end of the plane wave tube within the measurement range does not exceed 2dB, and the diameter of the plane wave tube is small enough, the reference diameter is 25.4mm (see WH/T 39-2009 and AES-1id-2012). ......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB/T 14475-2024_English be delivered?Answer: Upon your order, we will start to translate GB/T 14475-2024_English as soon as possible, and keep you informed of the progress. The lead time is typically 4 ~ 7 working days. The lengthier the document the longer the lead time.Question 2: Can I share the purchased PDF of GB/T 14475-2024_English with my colleagues?Answer: Yes. The purchased PDF of GB/T 14475-2024_English will be deemed to be sold to your employer/organization who actually pays for it, including your colleagues and your employer's intranet.Question 3: Does the price include tax/VAT?Answer: Yes. 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