speaker effiency

All things being equal, the more efficient speaker will also produce a higher sensitivity rating. The only reason that it would actually produce a lower SPL is if it was a very low impedance and the amp could not properly drive it. While most amps do not have a problem with higher impedance loads, dropping the impedance or using a speaker that is highly reactive can give some amps fits. The more difficult the speaker load, the less options that you have in amplifiers. Thiel's have always been known as "power suckers" even though their sensitivity rating is reasonable. They are a little tougher to drive than most other speakers and as such, require an amp with TRUE "hi-current" output. As to Jim's statements about efficiency being measured as a percentage, he is correct. As we've all seen, sensitivity and efficiency are often incorrectly interchanged for each other. Most speakers are VERY, VERY low in terms of efficiency even though you might see what we normally think of as being a very high sensitivity rating for them. Sean >

Spkrplus is correct in his differentiation of efficiency and sensitivity. Ask a speaker manufacturer what the "efficiency" of a model is, and in all likelihood, THEY DO NOT KNOW. It is a very complex thing to ascertain. I recommend that when you are seeking specs on a loudspeaker, you look at sensitivity, an impedence plot(rather than a nominal value), AND a plot of the phase angle. Phase angle is the most underappreciated spec in this whole argument. By, looking at the impedence and phase angle plots, you can often garner more information than you realized. By looking at a few specs provided by a manufacturer, we are often misled that a given loudspeaker will be easy or difficult to drive. In the real world, many speakers play a lot different than the spec in the literature. Another thing, if you can find out which drivers are used in the speaker, you can often go look at an spl(and impedance) plot(from the driver manufacturer). While this doesn't factor in the effects of the crossover, it can often tell you a lot. Example, if a driver's sensitivity is 88 dB/2.83V over most of its operating range, peaking at 92 dB/2.83V @ 1500 Hz, you can best believe the number you will be fed will be 92, when actually the number is more like 88.

I read somewhere that the reason that the term "efficiency" has fallen into disuse and "sensitivity" has supplanted it as the preferred terminology for describing a speaker's ability to convert an electrical signal to sound, is simply because, as stated by one of the above posters, normal efficiency for dynamic loudspeakers is between 1% and 5%. Supposedly, in the 70's, many speaker manufacturers decided, for marketing reasons, that an "efficiency" rating in the low single digits would cast a negative light on their products. Even combustion engines are more efficient, by somehing like an order of magnitude. Apparently, all but a small portion of the power output from our amplifiers is irretrievably lost. Sensitivity, expressed in Decibels relative to a watt input, is a more nebulous and tricky concept for the average audio consumer to grasp, but at least carries with it a nice high number. People (Consumers) like high numbers..... except in golf. I don't know if all of this is true. It would be interesting if someone could comment on it. Interesting thread. - Jim, I think you are definitely correct. Shame on R. V.... his speakers still sound good, though!

Amps supply more power into 4Ohms than 8. Check your amps specs and you will see this is true. Beware of low impedance loads with SET's, howevever. A sensitive 8Ohm speaker like the Soliloquiy's is the trick in this case.