What is "RMS" in speakers?

There is a lot of confusion out there about resistance ratings for speakers. I have even thought that occasionally the people publishing the specifications have had no clue what the scientific or correct definition of the term behind the published number means. I am going to clear away the fog from some of this and give you some helpful information that you can put to use and hopefully save yourself a great deal of the money and heartache that I was cost in the process of finding this information over the years.

The first term is "R.M.S." I think this term is abused by the consumer audio manufacturers more than professional, but I see both make errors. It stands for "Root Mean Squared". It is an equation essentially. For those of you who have forgotten or may not have taken much interest in math it does actually have a mathematical solution.

So what does all that mean? Keep in mind that all these equations and formulas are based on the theoretical perfection of a circuit as they relate to audio. Essentially you need to pay attention to impedance levels and make sure that you don't under-power or over-power your speakers with your amplifiers. It's not rocket science. I actually power my speakers with a slightly higher than listed amplifier rating, but I keep my output levels on the amplifiers turned down to reduce any audible noise in the amplifier circuit.

Let me give you some real world examples. Let's say you have a 200 Watt R.M.S. 8 Ohm Driver and a 250 Watt 8 Ohm Amplifier Output. Is this a problem? Probably not, unless you set the amplifier to full output and send some music program material through it. You just have to use common sense. (which is not often common) You shouldn't use a 100 Watt 8 Ohm Amplifier for the speaker though, especially if you aren't going to control who is dealing with the equipment all the time. It is quite likely that you could end up sending a clipped signal into the input of the amplifier and then it's just going to send that signal to the output only amplified. In effect that is feeding the speaker a DC voltage and if the coil isn't moving in the magnet it's going to cook it. This becomes especially critical in component systems with multiple manufacturers, impedance, and gain structures becoming a real variable.

If you pay attention to the rules of physics and sensibility and use the specifications as the guideline they were intended to be then you will always get better results.