Thursday, January 9, 2014

A Closer Look At The Term "Wattage" Of Home Audio Amps

By Sherry Lambert

Taking a look at a few of the technical specs of recent stereo amplifiers, one cannot help but be at a loss in attempting to evaluate different products and technical jargon, e.g. "t-amp", "THD" et cetera. In this editorial, I am going to have a closer look at one of the most essential of these terms: "amplifier output power". This term is also called "wattage".

If you are looking to acquire an audio amp to set up your home sound system, you will frequently be confronted with a number of weird terms describing its performance. But how do these numbers relate to how the audio amplifier sounds and how are these to be interpreted? Let me now go ahead and describe the power rating of power amplifiers. The output wattage of the audio amplifiers is shown as "wattage". This describes how loud your amplifier can drive your speakers. You want to select the amplifier wattage based on how big your listening environment is. For superior music quality, you might want to go with an amp that offers bigger output power than you need as many amps will exhibit rising distortion once the audio power increases.

"Wattage" is from time to time also called "Power" or "amplifier output power". To put it in a nutshell, "wattage" shows how high the amp can drive your speakers. The higher this number the louder your loudspeakers. You wish to select the audio amplifier wattage based on how big your listening space is. For superior music quality, you might want to go with an amplifier which has bigger power than you need since most amps will exhibit rising distortion as the audio power goes up.

Nonetheless, while the rms specification will tell you more about the amplifier's true performance, be certain however that the amp has a peak power rating which is substantially bigger than the rms spec. This is because very likely you will be using the amp to amplify music or voice. Music and voice signals inherently always vary in terms of their power, i.e. the power envelope of the signal will fluctuate over time. Having enough headroom is vital since audio signals differ a lot from sine wave signals which are used to measure rms output power. Short bursts of high power are repeatedly found in audio signals. These bursts will drive the amp into high distortion unless the peak power is high enough.

Usually the impedance of the speakers that you attach to the amplifier will determine how much power the amplifier may provide. Speaker impedance is measured in Ohms. Typically loudspeakers have an impedance between 4 and 8 Ohms. Amplifiers have a restricted output voltage swing because of the fixed internal supply voltage. As such the highest output power is going to differ depending on the speaker impedance. The lower the loudspeaker impedance the higher the highest power the amp is able to output. If the highest power is not referenced to a loudspeaker impedance, you should get in touch with the producer. Usually a 4-Ohm loudspeaker is used as a reference.

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