Likewise, we have to thank James Watt, Georg Simon Ohm, and Heinrich Hertz for their contributions to the industry. The “decibel,” one tenth of a bel and named for Alexander Graham Bell, recognizes his contributions to the understanding of sound. Incidentally, if you’d like a kind of immortality, be terribly clever and work out a system of measurement. Therefore, a 100-watt amplifier will produce sound only slightly louder than a 50-watt amplifier. If a sound gets louder by 3 decibels or “slightly louder,” it takes twice as much electrical power from your receiver or amp to produce that modest increase. That relationship is called “logarithmic.” If that word gives you an instant headache (nightmares of high-school math), then here’s a simpler explanation: So why doesn’t that 100-watt amplifier always sound twice as loud? Because the acoustic decibel–the decibel (dB) being the unit of measurement used worldwide to quantify the acoustic loudness of sound–has a peculiar relationship to amplifier power output measured in electrical watts. How loud is that? Hearing tests with large groups of people have revealed that a one-decibel (1 dB) change in loudness is approximately the smallest audible step that the average listener can detect, so an increase of 3 dB most listeners term “slightly louder.”
In the above example, the sound from the speakers would not be “twice as loud” it would only be “a little louder,” an increase of 3 decibels.
Not so.Īlthough it’s not the easiest thing to comprehend, doubling the amplifier power does not double the loudness. As audio/video hobbyists, most of us grew up thinking that if we have an amplifier with 50 watts of rated output power into 8-ohm speakers, and that combination produces reasonably clean and loud music, then by doubling the amplifier power to 100 watts per channel, the system would then play twice as loud.