Page 1 of Bass and RMS

I am going to be purchasing a surround sound system soon and i have a few queries about the subwoofer and stuff. First up what does RMS stand for and what is its significance? Secondly will i notice a huge difference between 20W, 25W, 50W and 70W for subwoofers? Is it just the loudness or is the bass a factor as well? All help will be appreciated.

Thanks

Hey there junior,
RMS stands for Roots Means Square,in laymans terms this is the amount of power in watts that the amp/speakers can handle over a continuous period.
You may have seen some manufacturers claiming "1000watts PMPO!!" from an aiwa mini hifi loaded with so many bass enhancement modes it simply begs belief.
This stands for Peak Music Power Output,which means that if ever the system amp was to reach its peak level,then this is the highest wattage attainable(this is very very rare by the way).
So,if you`re looking for a subwoofer,then the RMS figure is the one you should look out for.Bass takes up a large amount of amplifier power and on lower power systems puts massive strain on the amp(hence distortion)-this is why typically subwoofers have their own built in amplifier to ease the load from the main av reciever.
Personally,i reccomend you go for a sub with around 100-150 watts of power.Not because it will go deafeningly loud,but because all that power can be saved for the huge dynamic thuds and rumbles contained in the .1 LFE channel.Going for one without much power means it will run out of puff fairly quickly(and sound pants).
So,rms is the `real world` figure,pmpo is the `alice in wonderland` rating.
Whatever you do,DO NOT,confuse more watts as `really loud`-merely more room for dynamics and more room for the sound to breathe.
That should tie that one up,sorry this is a bit technical,but this is the only way to explain it!!

All the best

Westy