Juice Lighting & Sound  
               
  Decibel shown in ratio    
               
    Db GAIN        
    20 100        
    15 31.5        
    10 10        
    5 3.16        
    4 2.5        
    3 1.995        
    2 1.585        
    1 1.259        
    0 1        
    -1 0.794        
    -2 0.631        
    -3 0.501        
    -4 0.398        
    -5 0.316        
    -10 0.1        
    -15 0.0316        
    -20 0.01        
               
  The Decibel is a measurement of reference between two levels and not a  
  definite reference point in itself i.e. 0db has no figure until referred to another  
  relative point. Therefore a voltage difference can be displayed in Db's  
  for example the voltage difference between 1v to 0.5v could be displayed  
  as -50% or -0.5 of a volt or in Db's -3db. The same reference can be used for   
  the difference between 3v and 1.5v. The real usefulness becomes obvious when
  you are talking in large differences because Db's are logarithmic and therefore 
  fairly small figures in Db's can explain vast differences between reference points
  such as the huge gain form microphone level to line level within a mixer.