Logarithms for basic Audio Math are pretty easy, if you don't go too deep into them that is. If you can understand how they work and how to use them then thats all you need to worry about unless you want to be an acoustician.
Here's some stuff that the people above skipped over that you may not know:
the term dB is a ratio. If you say +10dB, and don't give a reference then it's like saying "Dang, she's ....". As such, there are many different reference points and thats what creates the confusing array of terms (dBv, dBV, dBSPL, dBu
etc...) SPL can't have a negative dB. It's bottom reference point is 0 which is the threshold of human undamaged hearing.
dBu is in reference to 0.775
volts across any load and is what is used as the dB reading in consoles and such. When the term 0dB is used on a console know that this means "same level in, same level out" as long as your eq is flat.
Here's some dB facts:
To increase a speakers SPL output by +3dB, one must double the wattage going into the speaker ie: 400watts = 101dBSPL, 800watts = 104dBSPL
To increase a speakers SPL output by +10dB, one must increase the wattage to ten times it's initial amount. 100watts=78dBSPL, 1000watts=88dBSPL
When the amplitude of a waveform is doubled, it is increased by +3dB
All these "+3 when doubled" facts are based off the 10Log formula which is as follows:
dBpower=10log(P1/P0)
there is also a 20Log formula
When you double the distance from a speaker, the dBSPL drops by 6dBSPL
dBvolts/
amps/SPL=20log(P1/P0)
for both, P0 is the reference point and P1 the value after change.
Here's another formula:
MS Decode (Studio Stero Pair Bi-Directional and Cardoid Mics)
(x+y)+(x-y)=2x
(x+y)-(x-y)=2y
2x/2y=x/y
Essentially you get a stereo pair out of 3 directions and 4 inputs.
I can dig up a whole bunch more for you if you're interested. Any questions just post and either myself or another on of us sound guys'll be able to answer it