BS 6840-9:1987

National foreword
Committees responsible
1. Scope
2. Object
Chapter I: Conditions for specifications and measurement
3. Conditions
3.1 Conditions for specification
3.2 Rated conditions and normal working conditions
3.3 Other conditions
4. General
4.1 General
4.2 General characterization of the devices
4.3 Comparison between characteristics of the devices
     and those of the amplifier
Chapter II: Characteristics to be specified and relevant
            methods of measurement
Section One - Artificial reverberation equipment
5. General
5.1 Definition of reverberation
5.2 Object
5.3 General characteristics
5.4 Special characteristics
6. Reverberation time
6.1 Characteristic to be specified
7. Various kinds of reverberation time
7.1 Initial reverberation time
7.2 Ultimate reverberation time
7.3 Method of measurement
8. Linearity
8.1 Characteristic to be specified
9. Frequency response
9.1 Characteristic to be specified
9.2 Method of measurement
10. Initial time delay
10.1 Characteristic to be specified
10.2 Method of measurement
11. Additional characteristics
11.1 General
11.2 Ambient acoustical noise
11.3 Safe life expectancy
12. General
12.1 Types of devices
12.2 General characteristics
12.3 Special characteristics
13. Delay time
13.1 Characteristic to be specified
13.2 Method of measurement
14. Echo
14.1 General
15. Echo time
15.1 Characteristic to be specified
16. Ambient acoustical noise
17. Safe life expectancy
Section Three - Frequency shift devices
18. General
18.1 General characteristics
18.2 Special characteristic
18.3 Characteristic to be specified
18.4 Method of measurement

Applicable to equipments which are considered to be amplifiers designed for special purposes.

This standard applies to devices intended to give reverberation, time delay and frequency shift to signals of an acoustical origin. It covers the types of devices commonly employed to achieve special effects in sound recording, broadcasting and public-address systems.