And to add to this: the 4 ohm (version of this woofer) is not just half the impedance of the 8 but instead is somewhere between 4 and 8. If u compare the spec sheets from Danley you can see that the minimum impedance of the newer version is 5 ohms! Maybe it should be called a 6 ohm box instead of 4. Further, the functional parameters of the woofers are slightly different as well so there are some slight differences in frequency response. But, the overall broadband output potential of each version should be basically the same. It's just a matter of how many volts it takes to get there. BTW, I like it when amp spec sheets also list total output swing in volts. Calculating back from power ratings takes time and isn't always accurate. Knowing the rail voltages of the power supply is nice too.

EXACTLY! That is the reason Danley gives the sensitivity in volts-instead of power.

The rating is for the closest "standard" impedance value.

Another "for example" is the SH50. Origionally it was rated as a 6 ohm cabinet-which more closely described the load it presented to the amplifier.

However I got calls ALL THE TIME with people asking about which amp to use for a 6 ohm cabinet. They could not find 6 ohms on the spec sheets of the amps. It really confused them-and when I tried to explain it, they go even more confused.

We changed the impedance rating to 4 ohms and all those phone calls stopped. It was now "simple". Since the origional specs were in input VOLTAGE-those numbers did not change. If we had used wattage-based on 6 ohms-then the sensitivity would have also had to change with the 4 ohm rating.

That is one reason why Danley uses the voltage method of sensitivity.

The "wattage" method is also flawed in that as the freq changes the sensitivity would also have to change-due to a different "wattage" being applied to a loudspeaker because of the different impedance.

You cannot apply 1 watt (evenly across all freq) to a loudspeaker. If you did-then the freq response would be quite different-because at the freq that have a high impedance-the freq response would have a corrispondingly higher output-which is not real and not what it sounds like.

You can only apply a voltage-and the wattage is calculated based on that wattage and "some" impedance-presumeably the rated impedance-even though that impedance may or may not be an accurate description of the load presented to the amplifier.

Amplifiers DO NOT produce a wattage output. They produce a VOLTAGE output that stay constant with varying loads (assuming the amplifier is not at the current limits)-so it makes more sense to rate the loudspeakers with a voltage (like the amps) rather than a wattage.