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Horn loudspeakers - Measuring methods
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GB/T 14475-2024
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GB/T 14475-1993 | English | 419 |
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Methods of measurement for horn loudspeakers
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GB/T 14475-1993
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Standard similar to GB/T 14475-2024 GB/T 51033 GB/T 50082
Basic data Standard 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| Word Count Estimation | 48,428 | Date of Issue | 2024-10-26 | Date of Implementation | 2025-05-01 | Older Standard (superseded by this standard) | GB/T 14475-1993 | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration |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/GBT14475-2024
ICS 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 Contents
Preface 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).
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