Simple question about amp and speaker wattage

[zener]

This questions would be very simple for you to answer since these are meant just to cure my ignorance :? .

Is there any rule on matching amp and speakers based on their wattage rating? I mean, can I hook up a 10w amp to just a 8w or less speaker? What would happen if so?

I asked it because I'm planning to hook up LM386 preamp through a bridged TDA2003 power amp that could deliver up to 20w to a 8" 18w speaker.

Thanks.

[Paul Marossy]

If you use speakers rated for less than your amplifier's wattage rating, you run the possibilty of damaging your speakers. It seems like most of the time, speaker wattage ratings are for peak wattage. In other words, a "100 watt" speaker can handle about 100 watts of peak power,  but something less than that for RMS power which may be around 70 watts or less at a certain frequency.

So, in your case, you could very likely blow your speaker, if you plan on playing it loud. It may be just fine if you never really crank it, too.

The other thing that is usually pretty important is matching impedances. If your amp needs an 8 watt speaker for it, then that it what you should use.