Istoria companiei JBL
Conform Harman Audio, JBL este unul dintre cei mai vechi si experimentati producatori de incinte acustice din intreaga lume, a fost fondata in 1946 de James Bullough Lansing.
Istoria companiei, insa, porneste in 1927 din parteneriatul lui Lansing cu Kenneth G. Decker si construirea unor difuzoare pentru radio si console, iar succesul apare odata cu realizarea primului sistem de sonorizare pentru un film difuzat in cinematograre, The Jazz Singer, in anul 1928.
In 1937, Lansing primeste un premiu pentru excelenta pentru ca a ajutat la stabilirea unor standarde inalte la nivelul industriei imaginilor in miscare (video), iar design-ul lor va fi copiat in anii urmatori de catre producatorii audio la nivel mondial.
Ulterior, compania s-a implicat activ in toate domeniile de aplicatie ale difuzoarelor, ajungand la peste 60% din piata aplicatiilor profesionale (studiouri, sali de concerte, cluburi, discoteci, stadioane etc) si la peste 80% din piata sistemelor de sonorizare pentru cinematografele certificate THX.
Harman International Industries
JBL este astazi parte a Harman International Industries, proiecteaza si construieste echipament audio pentru consumatori, industria de divertisment si industria de automobile. JBL are zeci de ani de experienta in producerea echipamentelor de sali de concerte si locuri publice si o foloseste pentru a crea echipamente audio pentru consumatorii din intreaga lume.
Fie ca este vorba despre un film, un joc sau un concert, cu ajutorul echipamentelor audio JBL va puteti bucura de o claritate excelenta a sunetului.
Conceptul Pro Sound Home, proprietar JBL, ofera utilizatorului acces la o calitate acustica comparabila cu cea standardizata in industria muzicii si a spectacolelor live.
Lucrarea prezinta aspecte teoretice cat si practice despre sistemele de sunet JBL.
Chapter 1: Wave Propagation
Wavelength, Frequency, and Speed of Sound
Combining Sine Waves
Combining Delayed Sine Waves
Diffraction of Sound
Effects of Temperature Gradients on Sound Propagation
Effects of Wind Velocity and Gradients on Sound Propagation
Effect of Humidity on Sound Propagation
Chapter 2: The Decibel
Introduction
Power Relationships
Voltage, Current, and Pressure Relationships
Sound Pressure and Loudness Contours
Inverse Square Relationships
Adding Power Levels in dB
Reference Levels
Peak, Average, and RMS Signal Values
Chapter 3: Directivity and Angular Coverage of Loudspeakers
Introduction
Some Fundamentals
A Comparison of Polar Plots, Beamwidth Plots, Directivity Plots, and Isobars
Directivity of Circular Radiators
The Importance of Flat Power Response
Measurement of Directional Characteristics
Using Directivity Information
Directional Characteristics of Combined Radiators
Chapter 4: An Outdoor Sound Reinforcement System
Introduction
The Concept of Acoustical Gain
The Influence of Directional Microphones and Loudspeakers on System Maximum Gain
How Much Gain is Needed?
Conclusion
Chapter 5: Fundamentals of Room Acoustics
Introduction
Absorption and Reflection of Sound
The Growth and Decay of a Sound Field in a Room
Reverberation and Reverberation Time
Direct and Reverberant Sound Fields
Critical Distance
The Room Constant
Statistical Models and the Real World
Chapter 6: Behavior of Sound Systems Indoors
Introduction
Acoustical Feedback and Potential System Gain
Sound Field Calculations for a Small Room
Calculations for a Medium-Size Room
Calculations for a Distributed Loudspeaker System
System Gain vs. Frequency Response
The Indoor Gain Equation
Measuring Sound System Gain
General Requirements for Speech Intelligibility
The Role of Time Delay in Sound Reinforcement
System Equalization and Power Response of Loudspeakers
System Design Overview
Chapter 7: System Architecture and Layout
Introduction
Typical Signal Flow Diagram
Amplifier and Loudspeaker Power Ratings
Wire Gauges and Line Losses
Constant Voltage Distribution Systems (70-volt lines)
Low Frequency Augmentation—Subwoofers