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by BongoMcCat 1656 days ago
> 20 dB represents a change of a factor of 10 in amplitude (volts), while 40 dB is a factor of 100, 60 dB a factor of 1000, and so on.

I always thought it was 10dB, or one B that was a change of factor 10. Have I missed something?
2 comments
variaga 1656 days ago
You're missing the distinction of power vs voltage. dB is defined in terms of power.

Power is proportional to voltage squared.

So a 10x increase in voltage == a 10^2 = 100x increase in power == a 20dB increase in power.

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js2 1656 days ago
TIL: Two principal types of scaling of the decibel are in common use. When expressing a power ratio, it is defined as ten times the logarithm in base 10. That is, a change in power by a factor of 10 corresponds to a 10 dB change in level. When expressing root-power quantities, a change in amplitude by a factor of 10 corresponds to a 20 dB change in level. The decibel scales differ by a factor of two, so that the related power and root-power levels change by the same value in linear systems, where power is proportional to the square of amplitude.

https://en.wikipedia.org/wiki/Decibel

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