Power Specifications for Amps and Speakers


As a continuation of last issue's topic on why you don't need a lot of power, this issue will cover power specifications. The emails I get show that there is a lot of confusion about power specifications for amplifiers and speakers and rightly so. There's a lot of misinformation going around so let me clear some of it up.


Amplifier Ratings

Amplifier's are rated by how much power they can deliver. Power should be measured in watts RMS and not in "peak", "max" or "music power". These are all bogus, inflated ratings and should be disregarded. The power specification can vary with the supply (vehicle) voltage and the load (total speaker impedance) on the amplifier. To compare one amplifier's output to another's it's important that the measurements were taken under similar conditions. Most power specifications should be stated like the following:


100 watts RMS, all channels driven from 20Hz-20kHz, into a 4 ohm load, 12 volt supply


You may have to look at the owner's manual to find these true specifications. Many amplifiers, even from the top brands, will print "maximum" power ratings on their amplifier heatsinks and product boxes. The power rating may also be given into a two ohm load or with 14.4 volts. Both of which can increase the power output. Make sure you're comparing apples to apples.


Speaker Ratings

Speakers also have a power specification but it is how much power they can handle, not how much they deliver. Speakers use power and amplifiers deliver power. This specification is also given in watts RMS. Peak power handling is often given as well but RMS is the one to pay attention to.


So the question many people will assume the answer to is, "Do speakers with larger power handling sound better or play louder?". The answer is a definite maybe. The ability to handle power by itself means virtually nothing. A speaker that will handle a lot of power may sound better because it is probably built better than a speaker with lower power handling. But that's not always the case and the only real way to tell which sounds better is to listen to them. It may also play louder because it can handle more power. But if it has a lower sensitivity than it may take twice as much power to play at the same level as a speaker with a higher sensitivity. And higher power handling may not even be needed. If your amplifier only puts out 100 watts than you don't really need a speaker that can handle 300 watts (though it doesn't hurt).


Matching Speakers and Amplifiers

Which brings us to the final point. Does a speaker that handles 500 watts need 500 watts to sound right? No! That speaker will play just fine with 50 watts. The higher power handling only allows it to handle more power which may make it play louder. If you want a more moderate power system than that's what you should deliver to the speaker. Speaker power ratings do not need to be matched with amplifier power ratings. As long as you stay at or below the power rating of the speaker you shouldn't have any problems with the sound or longevity of your equipment.

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