NOTE: THIS DOCUMENT IS OBSOLETE, PLEASE CHECK THE NEW VERSION: "Mathematics of the Discrete Fourier Transform (DFT), with Audio Applications --- Second Edition", by Julius O. Smith III, W3K Publishing, 2007, ISBN 978-0-9745607-4-8. - Copyright © 2017-09-28 by Julius O. Smith III - Center for Computer Research in Music and Acoustics (CCRMA), Stanford University
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Properties of DB Scales
In every kind of dB, a factor of 10 in amplitude gain corresponds to a 20 dB boost (increase by 20 dB):
and , of course.
Similarly, a factor of 2 in amplitude gain corresponds to a 6 dB boost:
A doubling of power corresponds to a 3 dB boost:
Finally, note that the choice of reference merely determines a vertical offset in the dB scale: