[jjk166]

Base 10 is certainly the default. Decibels are base 10; more specifically a Bel is 1 factor of 10, and a decibel is 1 tenth of that, ie 10^0.1.

[nick__m]

fractional exponents don't work like that, for example x^½ is the square root of x. You probably meant 10^-1 !

[jjk166]

No, 1 decibel is 10^1/10. Bels are multiplicative, not additive. You multiply 10^.1 by itself 10 times and you get 10^1. Similarly if you multiply x^1/2 by x^1/2 you get x.