JBL sound system design User Manual

Chapter 6: Behavior of Sound Systems Indoors .........................................................................

6-1

Introduction .......................................................................................................................................

6-1

Acoustical Feedback and Potential System Gain .............................................................................

6-2

Sound Field Calculations for a Small Room .....................................................................................

6-2

Calculations for a Medium-Size Room .............................................................................................

6-5

Calculations for a Distributed Loudspeaker System .........................................................................

6-8

System Gain vs. Frequency Response ............................................................................................

6-9

The Indoor Gain Equation ................................................................................................................

6-9

Measuring Sound System Gain ........................................................................................................

6-10

General Requirements for Speech Intelligibility ................................................................................

6-11

The Role of Time Delay in Sound Reinforcement ............................................................................

6-16

System Equalization and Power Response of Loudspeakers ..........................................................

6-17

System Design Overview .................................................................................................................

6-19

Chapter 7: System Architecture and Layout ................................................................................

7-1

Introduction .......................................................................................................................................

7-1

Typical Signal Flow Diagram ............................................................................................................

7-1

Amplifier and Loudspeaker Power Ratings ......................................................................................

7-5

Wire Gauges and Line Losses .........................................................................................................

7-5

Constant Voltage Distribution Systems (70-volt lines) ......................................................................

7-6

Low Frequency Augmentation—Subwoofers ...................................................................................

7-6

Case Study A: A Speech and Music System for a Large Evangelical Church ..................................

7-9

Case Study B: A Distributed Sound Reinforcement System for a Large Liturgical Church ..............

7-12

Case Study C: Specifications for a Distributed Sound System Comprising a Ballroom,

Small Meeting Space, and Social/Bar Area ...............................................................................

7-16