sensitivity vs power handling

[the_rookie]

The other day I was thinking about my new onkyo 876. Now compare it to a onkyo 506.

One has 140 watts of power, the other has 75.

At Reference level what difference are we going to hear?

Same goes for speakers, I looked at a high end polk, thats only rated 88db sensitivity, but with 300watts RMS.

My lower end polk is rated 150watts with 90db sensitivity. Whats the co-relation between sensitivity and watts?

[Sonnie]

Good question... and surely someone has a good answer.

I believe sensitivity is usually given as SPL with 1 watt at 1 meter.

It takes double the power to produce a 3db increase in SPL. So your high end Polks would need almost double the power to produce the same SPL as your low end Polks. I assume 2/3's more actually. 100 watts on your low end Polks will produce the same as 166 watts on your high end polks. I think that is how it works. Therefore, speakers with lower sensitivity need to be rated at higher power levels so that they can reproduce sufficient listening SPL.

[the_rookie]

Can anyone answer my question? I don't know too much about this topic, and was looking for an answer to clear up this greyed out area of knowledge...

[dgilme]

I thought reference level was a set db level at your seat? So if you are listening at reference level on both speakers you hear the same volume.

[tonyvdb]

I found this info here. Hope this helps

[the_rookie]

A few more questions than;

-What is the typical Wattage use for speakers during movies, or music?
-Based on the article, the wattage, RMS of course, is that the voice coils maximum continuous power capabilities? And for subs, is that the maximum continuous wattage for the amplifier or voice coil?
-And to ask my question again; my Polk R50's are rated to be 90dB with 150 watts RMS at 8ohm. While the LSi's, the 3K pair, are rated only at 89dB, with 350 Watts RMS at 4ohms; what does this mean for the speakers?

[robbo266317]

Each doubling of power is a 3dB increase in sound pressure.
So the Polk R50's are rated at 90 dB at 1 Watt. Therefore at 128 watts (the closest doubling of power near 150 Watts) is (90 + 7 * 3 dB = 111 dB)

The 3K pair are rated for 350 Watts which is between 8 and 9 (ie 256 Watts & 512 Watts) and are rated at 89 dB for 1 Watt.
So they would put out a maximum SPL of about 89 + 8.5 * 3 = 114 dB.
So the bottom line is that there is only a few dB in it at maximum power.
( note: These are only rough figures but should be close enough.)