Klark Teknik DN540 Manual Do Utilizador

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DN540
Operator Manual
5
 
Chapter 2: What Is A Compressor?
The natural sounds of everyday life, which can be caused by anything from, say, the 
falling of a leaf to the roar of a jet engine, vary extremely widely in sound level.  This 
variance is known as the “dynamic range” and is the difference — expressed in 
decibels (dB) — between the loudest and quietest sounds in a piece of audio, such as 
music or speech, or that can be reproduced by a piece of audio equipment without 
distortion.
The human ear has an automatic gain control that enables it to accommodate all of the 
sounds ranging from the threshold of hearing to near the threshold of pain, a dynamic 
range of approximately 120dB.  However, a dynamic range of this magnitude, even if it 
were possible in audio equipment, is not required in practice for comfortable listening.  
A sound pressure level (SPL) of 96dB would, in a domestic environment, almost 
certainly annoy the neighbours.  While, at the other end of the dynamic scale, a typical 
ambient noise level of at least 40dB SPL makes it impossible to use very quiet levels in 
recorded or broadcast sound media.  So, it is almost always necessary to compress the 
dynamic range of natural sounds to fit them into a window (usually about 30dB to 
40dB) suitable both for the equipment and for comfortable listening.
The compressor is a valuable tool for the control of the dynamic range.
Principles of compression
One of the principal uses of compression is the control of level in vocals.  Many singers 
train for years to achieve the degree of breath control necessary for an even tone and 
expressive performance.  Whereas, other vocalists rely on an instinctive voice 
production technique, which may need technological assistance to maintain a consistent 
level that sits correctly in the programme.
Figure 1: Compression - signal level graphs
Unprocessed signal
Time
Threshold level
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3:1 Compression above threshold
With make up gain added
Time
Threshold level
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Time
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Threshold level