The connection between loudness and amplifier power in term of stereos are often contain the connection between decibels (the measure of loudness) and watts (the measure of amplifier power). This connection can be a bit tricky, so here are some clue on how they two are relate.
Decibel was invented by Alexander Graham Bell, decibel’s description is: deci (meaning one-tenth) and bel (from Alexander Graham Bell, a unit of sound) so a decibel means one-tenth of a bel. Humans can hear a wide range of sound from a complete silence of 0 decibels to a painful to hear sound of 140 decibel, normal conversation sound is about 60 dB, while a close-range jet engine is about 120 dB. Human ears can recognize an increasing or decreasing sound level of 1 dB, anything less from 1 dB is hard to hear, and an increase of 10 dB or easy to hear sound level is consider twice as loud for most people.
Meanwhile watt is used to define energy, like horsepower and also joules. In audio term, watt is used to describe the amount of power from the amplifier or a receiver to the speakers.
Keep in mind that power output and speaker loudness is not linear, meaning that +10 watts is not equal to +10 dB. Now understand, a 50 watt amplifier and 100 watt amplifier will only have a difference of 3 dB, it’s not a significant number for human ear to hear the difference. So if you want your make a significant sound level difference you must get a 10x more power amplifier or 500 watts so it can gain a +10 dB increase. Understand this when you buy a new amplifier, 2x the power output will only give you +3 dB increase, 10x power output will give you +10 dB increase. Now you know the benefit of more power output.
