Speaker sensitivity vs SQ

Everything that I’ve ever read about dynamic speakers agrees with Duke’s friend's observations.

Bigger voice coil, more ventilation, lower power dissipation result in lower dynamic compression. Of course, all things are not ever equal, but the difference in engineering speakers for professional, continuous high power use vs. consumer speakers is all out there to read. If you want to maintain high output you must control the heat, weather by reducing power dissipated or increasing ventilation or both.


@audiokinesis

First, thanks to @b_limo for posting the DeVore video. I hadn’t seen that before and it is the best explanation of the relationship between sensitivity and impedance I’ve ever seen.

Several good answers to the original OP question but I wanted to add my own experience. For some reason I’ve been attracted to the sound of low sensitivity speakers for as long as I’ve had this hobby. It goes back to a pair of Large Advents that I bought in the 70’s after I heard a friends AR speakers. In a trend that has lasted my whole audiophile life, I invested in amplifiers that would drive difficult speakers. After I got my Advents I bought the biggest Marantz receiver they made (2325). Then I upgraded to an Adcom GFA 555.

When I upgraded the Advents in the early 90’s I listened to over a dozen models and I definitely preferred the less sensitive candidates. I settled on a pair of Mirage M3si which have an 87 db sensitivity. Then I upgraded my amp to a Krell KSA 300S. A few years ago I snapped up a pair of Thiel CS6 that a friend had for sale. These speakers driven by my monster Krell make some of the best sound I have ever heard anywhere.

When I went to AXPONA and the Tampa Show in 2018 I realized that I seemed to prefer speakers with lower sensitivity over those that were very sensitive. I didn’t hear a setup using a single ended tube amp that I lusted after. And I concluded that horn speakers aren’t my thing. They do some things very well but overall they just didn’t light my fire. But I can completely understand why some people love them.

My point here is that the sound resulting from the tradeoffs that low sensitivity speakers incorporate appeals to me for some reason. For the last 40 years I have been willing to invest in the amplification to drive these speakers and I’ve never regretted my decisions. Bottom line, high sensitivity or low sensitivity is not better or worse, it’s one of the many design decisions that speaker engineers make. Once they go a certain direction they optimize their design for the sound they want and sometimes that leads to low sensitivity and low impedance. I happen to be one of those audiophiles who is willing to suffer the cost and back problems of having an amp that will drive these things.

@erik_squires , thank you very much for that information on Siegfried Linkwitz's tone burst tests!    

I was aware of the article in Stereophile years ago which "debunked" short-term thermal compression, but the methodology in the test was flawed because it looked at the average compression over time, rather than the rapid-onset compression that Linkwitz's test reveals.    

"Bigger voice coil, more ventilation, lower power dissipation result in lower dynamic compression."    

That's my understanding as well, but JBL went a step further in their M2 studio monitor:  They use an alloy in the woofer's voice coil whose resistance stays essentially constant as it heats up.  I'm not sure whether they did this for the compression drivers' dual voice coils as well.  Anyway that seems to me like a brilliant idea which would be especially welcome in high-end audio speakers where efficiencies are lower and therefore voice coils are smaller.  

For the record, my own priorities are much more focused on speaker/room interaction, and the types of drivers which do what I want in that area just happen to be fairly high efficiency.  

Duke

That’s my understanding as well, but JBL...

@audiokinesis

Heh, I almost referenced JBL’s work in pro systems, as it’s among the most well documented and easy to find. Interesting 3rd way to skin this proverbial cat.

Also, I can’t type at all!

weather = whether

Also, while I believe it was Dr. Linkwitz, I cannot for sure remember, and I hope he doesn’t haunt me with bad crossover phase matching if I am mistaken in attribution. I do however remember the oscilloscope output very clearly. It was quite convincing.

While I do not need anywhere near JBL monitor style output, choosing tweeters with high power handling and very low measurable compression was a big goal for me.

I should point out that we should not attribute thermal compression to what might also be bad acoustics. Very reflective environments will have similar audible results, in at least as similar as you can type about them. A lot of bad / compressed treble complaints I’ve seen on audiogon were addressed with better room treatments. Was it excess reflection, or better treble/bass balance, or did the improvement in sound quality lead to turning down the knob, therefore reducing tweeter power dissipation? Really hard to say unless we are measuring. I sure could not explain in words how to hear a difference. :)

Best,

E

@erik_squires wrote: 

" I should point out that we should not attribute thermal compression to what might also be bad acoustics. Very reflective environments will have similar audible results, in at least as similar as you can type about them. A lot of bad / compressed treble complaints I’ve seen on audiogon were addressed with better room treatments. Was it excess reflection, or better treble/bass balance, or did the improvement in sound quality lead to turning down the knob, therefore reducing tweeter power dissipation? Really hard to say unless we are measuring. I sure could not explain in words how to hear a difference. :)" 

Your observation makes total sense to me. 

Dynamic contrast can be viewed as a "signal-to-noise-ratio" thing, and to the extent that undesirable/excess reflections raise the effective in-room "noise floor", they reduce the system's dynamic contrast.  I suspect this may be more common and/or often of greater audible significance than the short-term thermal compression revealed by those tone-burst tests. 

This "signal to noise" ratio thing has implications for the sense of envelopment as well:  The further down in level we can still detect the reverberation tails on the recording, the stronger the perception of the recording venue's hall ambience.  (This isn't the only thing that matters for "envelopment" to take place, but imo it's one of them.)  

The ear/brain system classifies reflections as such based on their spectral content, so imo it makes sense for absorption to be broadband, such that the spectral balance of the reflections is largely preserved (assuming they were spectrally correct to begin with).  If the spectral content of the reflections is skewed too much, they are no longer classified by the ear/brain system as "signal", and so they become "noise". 

Duke