speaker effiency

Speaker efficiency is the measure of how effectively a speaker can turn electrical energy in sound pressure. This is usually specified as db/watt. In simplistic terms, you can expect to have a specific sound pressure level for a specific power level applied to the speaker. Your power amplifier can pass more power into a 4 ohm load than an 8 ohm load, therefore, the higher power level presented to your 4 ohm speaker would result in a higher sound pressure level even though the efficiency is the same.

"Efficiency" is commonly mistaken for "sensitivity", as shown by the above poster. Efficiency is expressed in percent, representing how much electrical energy is converted into acoustic output. Both above postings are concerned with sensitivity, which is usually expressed as dB of output measured at 1M from a particular point of the source, with 1 watt input. This is complex, as different measuring points for the pick-up microphone will produce different results. Also the source's radiation pattern affects its rate of attenuation as a function of distance. The difference in output could be attributable to mistaken manufacturer specifications or a result of the 4 ohm speaker drawing twice the voltage of the 8 ohm speaker, or both. The question of whether or not the sub will match output is best answered by trying it out.

Correction on my last post, second to last sentence: replace "voltage" with "current"; duh...sorry.

Spkrplus, ok, what is it? Vandersteen says efficiency is measured in db/watt and Theil specs sensitivity in db/watt. I never saw any specs in terms of percent.

tend to agree more with Gmkowal