Speaker wattage rating techy issue

[Underground_Player]

In the world of hifi all speakers are rated to work between a minimum and a maximum wattage; 20-130 watts I think with my KEFs. Trying to drive a speaker hard with too little power is apparently worse than doing the same with too much power.
Guitar speakers are only rated for a maximum. Why is this? Is it possible to under-drive and damage a guitar speaker? I currently have a speaker rated at 150 watts (an Eminence Swamp Thang, which produces an excellent, very thick sound) in my 15 watt amp, and I haven't destroyed anything yet.

BTW the reason I ask is that I'd like to put a S.T. in an amp that is likely to have 10 watts at most, probably less, and don't want anything to go bang the first time I crank it.

Last thing - are there any other thick sounding speakers out there you guys would like to rate?


Thanks for any info, however nerdy, it's all good  :)

[TwilightOdyssey]

Trying to drive a speaker hard with too little power is apparently worse than doing the same with too much power.
Guitar speakers are only rated for a maximum. Why is this?

This is because the harder you push a loudspeaker, the greater the load is on the amp; when the amp runs out of steam, it puts pure DC out into the loudspeaker, which does two things --- shorts out the amp, and fries the loudspeaker. That's the layman's explaination; there are others who can explain all the technical why's and wherefores.

[HJM]

Basically forget what works in hifi world.....sort of

If you over run an underpowered amp trying to get more volume it distorts, a clipped waveform can kill hifi speakers much faster than too much power, so you're better with an overpowered amp that you're not going to drive flat out. It's not all that simple, but that's another thread....

With guitars distortion is good, especially if it comes from power valves!  So lower power amps can sound better for certain apps.  Just remember that the power handling is still a problem. It's best to go with at least double rating for speakers vs the output of your amp...ie 15w amp, min 30w speaker, because when those valves start to work they can put out a lot more watts than it says on the tin!

[HJM]

Trying to drive a speaker hard with too little power is apparently worse than doing the same with too much power.
Guitar speakers are only rated for a maximum. Why is this?

This is because the harder you push a loudspeaker, the greater the load is on the amp; when the amp runs out of steam, it puts pure DC out into the loudspeaker, which does two things --- shorts out the amp, and fries the loudspeaker. That's the layman's explaination; there are others who can explain all the technical why's and wherefores.

I thought I did the layman's explanation...that's more techy... :lol:

[Underground_Player]

PDT_003 Thanks guys, that was a perfect nerdiness level!

Swamp Thang for the Matamp it is then. Or an Eminence Tonespotter.

BTW I'd urge anybody reading who's looking for a loudspeaker to check out the new Emi Patriot/Redcoat series before immediately going for Celestion or Jensen; there seems to be a speaker for every need and in my limited experience of 1 speaker I'm prepared to stick my neck out and vouch for the range.





Nice dog HJM.

[Bob Johnson]

Another thing to consider with speaker ratings is that some speakers are  rated at what they can reasonably handle before they distort. This is usually well inside the continous rating of the speach coil and will depend a lot on cone construction, suspension at which point the magnetc field saturates. I think (please correct me if I'm wrong) Celestions are/where rated this.  
Others go by the continous rating of the speach coil only. i.e. the 15" speakers in our bands bass bins are rated at 350w RMS each but there's no way the cones could handle 350w of driving bass.
As HJM said the type of sound, clipped or square wave forms also give you speakers extra stress, with a square wave peak to peak is sustained for longer for a given frequency.