Speaker sensitivity vs SQ

@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

Greg Timbers:

Q: How has the sound of speakers changed over the years? Many yearn for the speakers of the past over those of today… what has changed? Distortion, materials, focus on sound characteristics?

A (by Mr. Timbers): Speakers have generally become smoother, more 3-dimensional and much smaller. This means that they are less dynamic on the whole and rather toy like compared to good stuff from the 60s and 70s. Unlike electronics, miniaturization is not a good thing with loudspeakers. There is no substitute for size and horsepower. Nothing much has changed with the laws of physics in the last 100 years so what it takes to make dynamic life-like sound is unchanged. There have been some advances in magnet materials and a bunch of progress in adhesives but not much else. The cost of a 70s system in today's economy would be considered unaffordable and the system would be deemed unnecessarily huge. The large highly efficient systems of old came at a time when 15 – 30 watts of power was the norm. Today's stuff would choke on those amplifiers. Now that power is cheap, size and efficiency has been thrown out the window because you can always apply more power. Unfortunately, more power does not make up for lack of efficiency. Today's speakers range between 0.1% to maybe 0.5% in efficiency. (On a good day) 60s and 70s stuff was more like 1% to 10%. With most of the losses gong to heat, turning up the power on a small system with small voice coils and poor heat management is definitely not equivalent to a large high efficient speaker.

It is true that the response of many of the old systems was a bit ragged and generally less attention was put in the crossover networks because simplicity generally means higher through-put. However, the big Altec's, JBL's, Klipsch's and Tannoys of the day would still fair well today with a little modernization of the enclosures and crossovers.

Today's multi-channel home theater setups let a bunch of small toy loudspeakers and a sub or two sound pretty big and impressive to the average Joe. I think speakers have mostly become a commodity and small size and price are what counts the most now. The few high-end brands left are struggling for market share in this age of ear buds.

https://positive-feedback.com/interviews/greg-timbers-jbl/

The few high-end brands left are struggling for market share in this age of ear buds.

Thanks great post...

It explain to me why my Tannoy were so good.... 😁

Alas! i own them no more...(2 pairs)

Happily my Mission Cyrus help me to forget them, they are very well embedded in all 3 dimensions, then even if they are not on par in quality with the Tannoy, they sound better than my Tannoy non well embedded ever sounded to my ears...

I will not go further, the word "embeddings" is not very liked, being not understood....

My best to all...

A note: someone not tired to read all day long reviews of costly new electronical design possible "upgrades" said that my "evangelization" of people is too much for his ears.... It is unbeliveable that people are so gullible to throw their money without thinking about the way to use in the better way possible what they already own....




«You can change opinions, you cannot change science»- Harpo Marx

«It is like reverse engineering brother, you can change science and after that opinions change»-Groucho Marx