Avoiding the error of purchasing and using an inadequate amplifier based on misleading wattage claims

At some point in the past, certain power amplifier manufacturers got hip to the fact that the only specification most power amp buyers pay attention to is wattage.

Sadly, they decided that misleading specs were OK as long as it created better sales. Hmm....

For purposes of our discussion, let’s consider two amplifiers. Amplifier A is rated at 1,000 watts (per side), into a 2-ohm load, with .1 percent Total Harmonic Distortion (THD), measured at 1 kHz, while Amplifier B is rated at 1,000 watts (per side), into a 4-ohm load, with .03 percent THD, measured full range from 20 Hz to 20 kHz.

Let’s break this down, starting with load. All amplifiers, regardless of manufacturer, will provide more power into a 4-ohm load than into an 8-ohm load. Less resistance from the loudspeaker(s) will allow more output from the amp.

Similarly, the amp (if it will run at 2 ohms; some would rather not) will provide more power into a 2-ohm load than a 4-ohm load for the same reason: less resistance.

Let’s imagine you have four 8-ohm loudspeakers all running off of one channel of Amplifier A (which results in a 2-ohm load at the amp output, and most professionals won’t do this). Each loudspeaker is provided with 250 watts.

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