At the most basic level, power amplifiers convert a input signal into a more powerful signal - with minimal distortion. On its own, a weak audio signal (from a mixing board, preamp, etc.) produces a modest electrical current. But this current isn't powerful enough to move the cones within loudspeakers; these cones are vital for translating electrical signals into audio. Power amplifiers, then, act as a middle man; they boost weak input signals to line levels that are compatible with speaker systems. For example, a power amp might take a 700 microwatt input signal, and convert it to a 700- or even 7,000!- watt signal. High-quality power amplifiers do this without distorting, or otherwise jeopardizing, the original audio signal waveform.
Finding Your Perfect Power Amp
Power amplifiers aren't stand-alone devices; they function within larger elements of live sound equipment. So finding the right power amp is dependent on the rest of your gear. What's the power-handling capacity of your loudspeakers? Which kinds of preamps do you already have? How big is the venue? Power amps come in single-channel, stereo (two channels), or multi-channel models: with different wattages, and hosts of different features. Power amps also fall into different classes, each with its own advantages. For example, Class D power amps are known for both their efficiency and their resistance to overheating.
Today, most power amps aim for an optimal mix of power, portability, and fidelity to the original signal input. The Behringer iNUKE NU6000DSP is a quintessential example; at only 12 pounds, it's super portable, and its Class D technology means it'll always stay cool. The NU6000DSP contains two channels, each with 3,000 watts of power at 4-ohm impedance. Its "DSP" - or digital signal processor - allows mixers to assign effects like EQ, delay, etc. to specific channels. Because the NU6000DSP can control, say, delay from its front panel, there's no need for separate delay devices. In this way, DSPs streamline the amplification process.
