Decibels and Power

Decibels can also be used to compare amplifier power, or the output from various numbers of loudspeakers. What you will quickly find is after the first few additional amplifiers, the amount of additional decibels you are buying drops off pretty fast. It makes a much bigger difference to go from a 100 watt amplifier to an 800 watt amplifier, than it does to move up from a 10,000 watt stack of amplifiers to a 20,000 watt stack of amplifiers. This is especially critical in large sound system designs, where a 3 decibel error in calculation of required amplifier power could mean an error of 10,000 watts. This can apply to loudspeakers where all the loudspeakers provide coverage of the same area. This is a power ratio in both cases, and as such is a bit different ratio than the distance/attenuation calculation above. This formula looks like this: Decibels of Change=10xlog(power 1/power 2).