The Decibel

Recall that a loss is expressed as negative dB's.
As an example:

100 x .7 = 70
We know 100x is 20dB, but what is .7x,
i.e. what is a gain of .7 expressed in dB's??

Pull out your calculator (or use the PC's calculator at Start,Programs,Accessories).
Enter .7 and press log. You should get about -0.1549
Then if you remember the factor of 10 in the definition of a dB, a gain (loss) factor of .7 is -1.549dB

So the gain expressed in dB's is
20dB - 1.549dB = 18.45dB
Now let's use the calculator again to verify that 18.45dB is indeed the total gain factor of 70!
Divide by 10 to get 1.845, enter 1.845, press Inv (Inverse; or an equivalent on your calculator) and press log.
Did you get about 69.98 like I did !?

End of The Decibel