05-10-13: Mattmiller
Efficiency and Sensitivity are words that get confused when talking about speakers.
That is true. But I don't think that the references to efficiency in several of the earlier posts represent unreasonable uses of the term.
Strictly speaking, speaker efficiency would be defined as acoustic power out vs. electrical power in. It would be expressed as a percentage, and would be a very small number for nearly all speakers. It would also be a number that is rarely specified, and that is not particularly helpful.
It is common, though (and reasonable, IMO), for the term "efficiency" to be used to refer to sound pressure level at a distance of 1 meter in response to an input of 1 watt. And for "sensitivity" to be used to refer to SPL at 1 meter in response to an input of 2.83 volts.
2.83 volts corresponds to 1 watt into 8 ohms. So for an 8 ohm speaker "efficiency," per that loose definition, and "sensitivity" would be numerically identical. For a 4 ohm speaker, efficiency per that definition would be 3 db less than sensitivity, since 2.83 volts into 4 ohms corresponds to 2 watts. That difference will have greater significance in the case of a tube amp than a solid state amp, because the power capability of a tube amp into 4 ohms will generally be similar to its capability into 8 ohms, while the power capability of a solid state amp into 4 ohms may be as much as twice its capability into 8 ohms.
On another note, in my previous post when I said:
Another point I would make is that IME a forte of tube amplification tends to be imaging and dimensionality. Although I have no basis upon which to be certain, my suspicion is that that is not a strong point of these speakers, and that potential benefit of tube amplification would likely be wasted on them.
it occurs to me that my wording could be taken more negatively than it was intended, due to my use of the word "wasted." To clarify, my intention was just to say that I suspect that the potential benefit that IMO tube amplification can often provide with respect to imaging and dimensionality would probably not be realized with AR9 speakers. One reason for that suspicion, in addition to its general configuration, is the comment in the review I linked to that the AR9 is designed to be placed close to the wall, which usually results in imaging being compromised to some degree.
Regards,
-- Al
