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GB/T 14475-2024Horn loudspeakers - Measuring methods (English PDF)

号筒扬声器测量方法

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Issued by

State Administration for Market Regulation; Standardization Administration of China

Level / Type

National · Recommended

Issue date

October 26, 2024

Implementation date

May 1, 2025

Scope

GB/T 14475-2024 is the English-translated version of 号筒扬声器测量方法.

GB/T 14475-2024 is the Chinese standard "Horn loudspeakers - Measuring methods". Its scope clause reads: 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. Its clauses include terms and definitions.

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Document preview — GB/T 14475-2024

National Standard of the People's Republic of China

ICS: 33.160.99
Classification: M72

Issued by: State Administration for Market Regulation; Standardization Administration of China

Preface
1 Scope
2 Normative references
3 Terms and Definitions
4 Measurement signal
4.1 Overview
4.2 Sinusoidal Signal
4.3 Broadband Noise Signal
4.4 Narrowband Noise Signal
4.5 Pulse Signal
5 Acoustic Environment
5.1 Overview
5.2 Free field conditions
5.3 Diffusion field conditions
5.4 Simulating free-field conditions
6 Unwanted acoustic and electrical noise
7 Positions of horn loudspeaker and measurement microphone
7.1 Measuring distance under free field conditions
7.2 Position of horn loudspeaker under diffuse field conditions
7.3 Position of horn loudspeaker and microphone under simulated free-field conditions
8 Measuring equipment
9 Accuracy of acoustic measurements
10 Horn Loudspeaker Installation
11 Preload Processing
12 Polarity Mark
12.1 Feature Explanation
12.2 Test Method
13 Reference planes, reference points, and reference axes
13.1 Reference surface
13.2 Reference Point
13.3 Reference axis
14 Passive horn loudspeaker (without matching transformer)
14.1 Measurement conditions
14.2 Impedance
14.3 Input Voltage
14.4 Input power
14.5 Rated frequency range
14.6 Sound pressure in free field conditions
14.7 Response under free-field conditions
14.8 Output power (sound power)
14.9 Directional Characteristics
14.10 Amplitude Nonlinearity
15 Passive horn loudspeaker (with matching transformer)
15.1 Measurement conditions
15.2 Matching Impedance
15.3 Input Voltage
15.4 Input power
15.5 Rated frequency range
15.6 Sound pressure in free field conditions
15.7 Response under free-field conditions
15.8 Output power (sound power)
15.9 Directional Characteristics
15.10 Amplitude Nonlinearity
16 Active Horn Loudspeaker
16.1 Measurement conditions
16.2 Input Voltage
16.3 Rated frequency range
16.4 Sound pressure in free field conditions
16.5 Response under free-field conditions
16.6 Output power (sound power)
16.7 Directional Characteristics
16.8 Amplitude Nonlinearity
17 Stray magnetic field
17.1 Static Component
17.2 Dynamic Component
18 Size and Quality
18.1 Dimensional Measurement
18.2 Quality Measurement
Appendix A (Normative) Listening Test
Appendix B (Normative) Insulation and Environmental Adaptability

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).

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 45 pages — is available in the English PDF.

Referenced standards

Normative references

Cited by

GB/T 14474-2024Horn loudspeakers - General requirements

Similar standards

GB/T 14199-2010|GB 4877-1985|GB/T 10239-2011|GB/T 12199-2000|GB/T 14109-1993

Editions of GB/T 14475

Edition	Title	Revision	Status
GB/T 14475-2024	Horn loudspeakers - Measuring methods	current edition	Current
GB/T 14475-1993	of measurement for horn loudspeakers	previous edition	Superseded

This page sells the current edition, GB/T 14475-2024. Earlier editions are listed for reference only.

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