I'm just going to quote myself here:
"What is a monitor? An audio monitor is a speaker, or more commonly, 2 speakers in the same enclosure (tweeter for high frequencies, woofer for low frequencies) that is designed for critical listening. Some have built in amplifiers (active or "powered" monitors). Others require a separate power amplifier to drive them (passive monitors). Your home stereo or computer speakers are not monitors. They are designed to sound good, not to tell the truth. They don't reproduce frequencies that are not part of the music, and are designed to reduce or eliminate hum, hiss, crackle, rumble, boom, white noise, or anything else that isn't part of the music. Monitors are designed to reproduce everything that is on the recording, including things that suck. If you can't hear it, you can't get rid of it. The difference between audio speakers and monitors is the difference between a made up, airbrushed, mood lighted picture of a Playboy centerfold, and the way she looks when she gets up in the morning with a hangover and no makeup.
As such, monitors are absolutely necessary for mixing and mastering audio. No, you can't do it with even very good stereo speakers, or headphones, or anything else, and get good results. Some systems use a separate subwoofer. Because bass frequencies have such a long wavelength, they reach the 2 ears at pretty much the same time and amplitude. Therefore, a sub will have a crossover, which sends frequencies below a certain setpoint to the sub, and frequencies above the setpoint to the left and right main speakers (mains), sometimes called satellites. In passive systems, if a sub is used, there is usually a separate crossover unit, after the power amp, that does the same thing.
Proper monitors are one of the most important parts of a recording studio, and are often underfunded by people who have convinced themselves they can do without them. I would say that monitors are an essential item that should be on any projected studio gear list. Expect some sticker shock here, as good ones are quite pricey. Remember, one of the things monitors help you to do is find noise. That means that if monitors *make* noise, they are pretty much useless. Amplifiers and speakers that make damn little noise don't come cheap. Get over it. Hope that helps."
Everything I said above about home stereo speakers goes double for PA cabs.
How bad is it to use PA speakers for monitors. How bad is it to use a Daisy rock guitar to play Black Flag?-Richie
