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speaker sensitivity dividing lines

What do you consider to be the dividing lines between low sensitivity, medium sensitivity and high sensitivity speakers ? Here are some thoughts on the subject and please keep in mind that i'm basing these spec's on the speaker being fed 1 watt @ 1 meter with the results averaged over a wide frequency bandwidth ( 100 Hz - 10 KHz). While this "somewhat" takes the impedance variance out of the equation due to using 1 watt rather than 2.83 volts, a speaker that is more sensitive may not be "easier" to drive due to high levels of reactance and / or impedance swings. As such, the lines between a "resistive 92 dB speaker" ( medium sensitivity ) and a "reactive 95 dB speaker" ( high sensitivity ) could be blurred in terms of why a big amp can't drive a more sensitive speaker but a smaller ( yet "beefier" ) amp can. Then again, that is a whole 'nother can of worms for another thread.

The reason that i bring this up is that we may all have slightly different ideas as to what is high / low sensitivity. In order to make conversations a little more easily understood and get to a point where we are all on the same page, coming to some type of mutual understanding as to what we are using as reference points might make things easier. I think that this would come in handy for such things as an "Audiogon FAQ's" type of section that will probably pop up sooner or later.

As such, these are the basic guidelines that i tend to follow when looking at speaker sensitivity with the above criteria taken into account. I'd like to hear from others as to what their "dividing lines" are and how we could come up with an "Audiogon reference" when discussing speakers & efficiency ratings.

83 db's and below = ultra low sensitivity

84 - 87 dB's = low sensitivity

88 - 92 dB's = medium sensitivity

93 - 97 dB's = high sensitivity

98 dB's and above = ultra high sensitivity

Obviously, these figures are somewhat random but you have to draw the line somewhere as far as "spec's" or "performance on paper" goes. Any and all comments / suggestions welcome. Sean
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sean
sean OP
6,229 posts
 
Unsound: In the days of yesteryear where sealed designs walked the Earth in great numbers, there were TONS of speakers in the 85 - 88 dB range. Since driver technology has increased over the years, vents of one kind or another are FAR more common and many designs "share the load" with multiple drivers covering the same pass band, efficiency has crept up a bit over the old school "one driver per passband" sealed box of yesteryear. From what i've seen, I think that most speakers are in the 88 - 91 dB range nowadays. I could be wrong though and that's why i asked for other points of view. Sean
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gs5556
769 posts
 
I would factor in amp/preamp gain also. I have a 26 db gain preamp and a 4 db gain 2A3 SET and 86 db @2.83V/4ohm speakers. This front end has about the same effect on these speakers as a 100W amp with a typical 12db gain preamp (but at different volume settings). So, to a low gain front end, they would be "low" sensitivity. But to a high gain front end, they act as a higher sensitivty speaker. Maybe that's one reason, along with the level of our recorded source material, why we have different opinions as to what we call what. With that aside, I would call anything over 90db/1w/1m "high" sensitivity, anything below 85 "low" and in between "typical" since that is what I think most speakers are - 86 to 89.
unsound
6,115 posts
 
I wonder if the resurgence in SET amps and Horn loaded speakers has rearranged the dividing lines. Panels speakers seem to have become more effecient, especially since many more, now have dynamic cones for the lower frequencies.
sean OP
6,229 posts
 
Gs: Correct me if i'm wrong, but you can only put so much signal into any gain stage before it begins to distort and overload. On the same hand, an output stage can only put out so much power before it starts to distort and overload. As such, driving the piss out of ANY part of the system is going to result in distortion being fed to the speakers and your ears. Obviously, it might sound a lot louder ( distortion of any type typically increases "apparent volume" ) but you are still limited to X amount of signal at a "relatively clean" level. I do agree that tubes overload more gracefully ( with less "nasty" distortion ), which allows one to push them harder with less listening fatigue though.

Having said that, I don't think that ones' electronics has anything to do with the sensitivity rating of a pair of speakers. Whether or not said electronics will drive a set of speakers to "good" or "comparitively loud" levels is another story. That, as far as i can tell, is food for another thread. Sean
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subaruguru
1,353 posts
 
Too many manufacturers spec a bit optimistically, I've noticed. How many 88dB/w claims end up a dB or two short over at JA's bench, for example. Sensitivity averages at 1k are usually predicated on midrange sensitivity, which hovers around 88dB unless squashed down to build bass in a small sealed 2-way, for example. Higher sensitvity numbers also abound with MTM (D'Apollito) arrangements, as the tweeter can now run pretty straight out, yielding some 90-91 designs.
An equally important corollary is room liveliness. My 88dB Spendors in my lively HT large toom are a LOT louder with a watt than my Parsifal Encore 88dB in my very damped smaller living room. I don't doubt that the difference is at least 3dB, or 1/2 amp power.
A good example of the design decision exists within the Spendor range. The small 3/5 comes in only at 84-85 dB/w.
In the larger SC3 center channel Spendor simply adds a second mid/woofer to make a horizontal MTM. The tweeter padding is now loosened, and a GREAT 88dB speaker is born.
In some ways I prefer its sound to the previous method they used to raise efficiency: the 6.5" two-way 3/1p I have flanking the center. Same efficiency, slightly different tonality. So it may be that the popularity of D'Appolito designs has raised the average efficiency across the market.
Then there's the curve-bump down at SET-land, with those 95 dB midrangers sucking 2-10watts, eh?
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