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LOUDSPEAKERS - AN IN DEPTH LOOK:

Wattage Ratings

Often, consumers are attracted to and impressed by speakers that can handle the largest amount of wattage. However, wattage is just one factor to consider among many. Just because a speaker can handle more wattage does not necessarily mean that it will play louder or sound better.

To find out the real story, one needs to consider the sensitivity specification together with the wattage rating. The sensitivity specification basically states how much sound comes out for a given input (analogous to a miles-per-gallon rating for a car). The sensitivity spec is determined by the manufacturer, and often takes the following form: "x" dB / 1 watt / 1 meter. "x" is the sound level in dB, and may be anywhere from about 85 to 105 dB, depending upon the speaker model (a spec in the low to mid 90s is common). The spec is determined (at the vendor's factory) by driving the speaker with 1 watt of electrical energy and measuring the acoustic output at a distance of one meter (using a calibrated microphone). There are a number of variations in measurement procedures due to the variety of speaker models, too many details to cover at this time.

So, what does this all mean? Consider two speakers, Model A and Model B. Model A has a wattage rating of 200 watts and a sensitivity rating of 101dB/W/M. Model B has a wattage rating of 600 watts and has a sensitivity rating of 97 dB/W/M. The maximum output from Model A (with 200 W input) is 124 dB; the maximum output of Model B (with 600 W input) is 124.8 dB (most people would not be able to hear a 0.8 dB difference in sound level). So, as can be seen from the numbers, Model A and Model B have nearly identical maximum output, even though Model B can handle three times as much power! (I haven't gone into mathematical details of how I came up with the maximum numbers... a topic for another day). It is interesting to note however... for top end speakers (of the same type), the maximum output of them are all similar. In other words, speakers that handle a lot of power often have lower sensitivity numbers. Speakers with the highest sensitivity numbers typically can't handle as much power. You are not likely to find a speaker than can both handle a ton of power and also have a high sensitivity rating. Amplifier power is relatively costly, so speakers that are more efficient (generate more sound with a smaller input) are generally desired so long as you are satisfied with the sound characteristic.