How important is the efficiency of a speaker to you?

@lonemountain wrote:

... If you are more open minded and are wiling to look at moderate efficiency speakers in the mid 80s, using the wide array of excellent high power amplifiers available, or active speaker configurations, you can have your low distortion, wide dynamic range AND better bass AND wider dispersion, etc, etc. But you cannot have all that AND super high efficiency.

Sorry, but the above makes little sense to me. 

If by "mid 80s" you mean sensitivity in dB's, then it's a very low efficiency design (i.e.: ~0.2%) and not "moderate" by any means. 105dB's sensitivity on the other hand translates to 20% efficiency, which is very efficient. 

Contrary to your views I find efficient speaker designs - say, from 95-100dB's on up - to be the best way to achieve the combination of low distortion, wide dynamic range AND better bass, with the proviso that the latter requires large size to achieve a fairly deep extension, but that's not a design deficit nor a sonic impediment. And, if I'm to understand you correct, wide dispersion isn't a trait, but a characteristic; if anything a narrow and fairly uniform dispersive nature has advantages over a wide and likely uneven ditto. 

Finally, high efficiency speaker designs can as well and advantageously be run actively. In fact I find that's where they really shine.

Problem is that they also require a very large ss amp upstream to drive them. Something that can push a lot of current, which pretty much rules out most low-mid ( maybe even high) powered tube amps. When I mentioned this to the person doing the demo, i was basically belittled, as he felt that the efficiency of a speaker is pretty much irrelevant ( well he would, as he is trying to sell these speakers). The speaker line is fairly well known to drop down to a very low impedance level in the bass regions. This requires an amp that is going to be $$$, as it has to not be bothered by the lowest impedances.

Low impedance and low efficiency is a bad combination if you want the best out of your amplifier, regardless of the amplifier type.

@ditusa has put his finger on a serious problem with lower efficiency speakers, one that isn't overcome by higher amplifier power, in fact makes it worse.

But you also have the problem of distortion from the amp. With any amplifier, the harder it has to work the more distortion it will make. So 4 Ohm distortion is always going to be higher than 8 Ohm distortion. You might think that small increase isn't audible but that would be ignoring how the ear perceives sound and in particular, tone color and sound pressure.

Sound pressure is perceived through the higher ordered harmonics, If you increase them by even tiny amounts its audible as greater loudness (BTW this is easy to demonstrate through simple test equipment).

Distortion modifies the tone color of instruments by adding harmonics. IOW the ear perceives harmonics as a tonality. So adding even a slight amount of distortion will color the sound and very likely in the direction of 'harsher' and 'brighter'.

Put yet another way, if a speaker could be made to be 8 Ohms instead of 4 without changing anything else, the perception would be that the speaker became smoother and more detailed simply because any amplifier driving it would have less distortion.

So efficiency and impedance are both important!!

@phusis

I normally agree with your posts, but not this one. A transducer engineer like Doug Button (he worked at EV when I did, and then again at JBL when I was there) or Rich at ATC would agree with my post (maybe not exactly the way I say it). The physics of the speaker is a balancing act: if you want more efficiency you give up other advantages. Im not saying this is wrong, it’s simply a choice. A moderate efficiency speaker (86dB 1w/1m) is not a mistake either as it is just a different choice that enables other performance features that high efficiency cannot offer. You cannot have it all. My point is simply that this thread seems to universally promote that high efficiency is the primary hallmark of high performance and that is simply not true. It can be important if you need High SPL, or like horns or big wave-guides (which can image well), or use speakers in a highly reverberant environment where narrow dispersion is an advantage, but these conditions certainly don’t exist in every room or for every listener. It’s a trade off and is not a "good or bad" or "right and wrong" thing. Decide what you want, then figure out what speakers do that.

A good example of deciding what’s important to you is a listener in a small space; a small stand mount speaker with excellent low frequency output, say a LS3/5a type KEF design would be a good choice. Super high efficiency is not gonna happen in this type of design. If a listener wants wide dispersion speaker because he/she wants it to sound the same anywhere in front of the speaker, super high efficiency is not gonna happen. If a listener wants super low distortion because they are in mastering or recording, then super high efficiency is typically not a goal. The hardest part may be understanding what you want in your space vs what other people want in their space, as the reviews say this is good or bad but don’t really discuss the space or the listeners goals much. Whether it’s good or bad is ALL about matching your space and your goals with a speaker. High end speakers are not good or bad on some universal scale. There are too many engineering goals/design features to account for that define good or bad in a given space. Efficiency is just one of these many features.

Brad