Speaker db rating?

Is this what what your looking for.Amplifier Power Required

http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm

Hemihorn- That's a really cool tool. Thanx for posting it!

A "rule of thumb" that I've seen in high-efficiency speaker circles is for the speaker/amp combination to be able to reach, on paper at least, 102 dB at one meter.

Each doubling of power is theoretically 3 dB more output, so 8 watts is three doublings of the 1 watt efficiency = 9 dB more output than the speaker's rated efficiency. So in theory if the speaker is rated a 93 dB for a 1 watt input, you'll be able to reach 102 dB with an 8 watt amp.

Now there are other considerations. For example, will the speaker run into problems before you get to 102 dB? Many single-driver speakers can handle much more than 8 watts thermally, but in the bass region will be driven beyond their linear excursion limits with much less than 8 watts input and therefore will lose coherence and articulation as the voice coil spends time outside of the magnetic gap.

Also, what does the speaker's impedance curve look like? If the impedance curve has nasty swings (especially above the bass impedance peaks), then the amplifier may clip long before it gets to 8 watts.

In defiance of the 102 dB rule of thumb, I paired up a smooth-impedance 92 dB speaker with a 5-watt amp at an audio show, and the only audible distortion came on loud solo piano. So that would have been enough power for some people, but not enough for others.

Best of luck,

Duke
dealer/manufacturer