Speaker Wattage

[Rick Hardslab]

I've heard that running a high wattage speaker at a low wattage is bad.  The reasoning behind it being that the speaker will start breaking up much sooner than it wants to and will be vibrating much faster at low thresholds.  Is there any truth to this?

[John Lyons]

I don't think you will have any problem with what you describe.
Sometimes you can hurt a speaker from clipping a small amp into it but this is mainly a Home stereo PA issue where the signal is meant to be clean and it is trying to reproduce s large square wave. Running a small guitar amp into a higher wattage speaker is fine. Even running a big amp into a low wattage speaker is fine if you keep the volume low.

John

[gez]

I think you've got things the wrong way round (overdriving a low wattage speaker can be bad for it).

[Elektrojänis]

Like basicaudio said this misunderstanding probably came from the hifi or pa world. The problem there is usually that the tweeters of the speaker system will overheat and die. Even there the problem will not be that the speakers will break up at lower levels. Basically a 100W amp with the volume set to produce 20W will produce the same signal that a 20W amp with the volume se to produce 20W. As long as the amp will not clip and you are putting out too much power, the speaker will not mind. The problems start when you overdrive the amplifier and it will clip.

Here is a nice article about it: http://sound.westhost.com/tweeters.htm

Even though the example in the article is a 100W amp into a speaker system rated at 100W, you can produce enough treble from lower power amp to burn a tweeter from a speaker system rated for higher power. Lower power amp will clip earlier and the clipping will produce high frequency harmonics that add to the treble that might allready be on the limits of wht the tweeter can handle.

Guitar speakers/cabinets usually don't have tweeters (exeption is some stuff meant for acoustic/semiacoustic) guitars. They practically have only woofers and those woofers are usually designed to be driven to their limits. Actually some of them are designed to produce some subtle soft distortion when they are driven hard. Hifi woofers on the other hand usually distort wery little before they just die (the voicecoil former starts hitting the bottom of the magnet assembly and distorts or the voice coil overheats, depending on the frequencies involved and the design of the woofer itself).