So "when you can SEE the cone move, that is harmonic distortion".

NO IT’S NOT. On what planet? If you can’t see a speaker move at 60 hz with volume up, what am I seeing? It is NOT distortion.. it’s a 60 hz note being playing at a higher volume. Distortion ONLY comes into play when you can’t stop the cone from moving.. THE exact opposite of what was said..

Pro drivers are excited with LOWER voltage, or less power. Normally High E speakers don’t have high excursion. The lack of excursion is usually made up with by increasing the cubic inches of surface area on the drivers cone.

NO matter the design, the bottom line, AIR is required to move to make sound. The more air that moves the louder the sound. No air, no sound!!

The trade off is simple. The larger the cone surface you have, the more "second wave" distortion. That’s right that BIG HIGH E speaker is a collector of what comes BACK to hit the cone surface. The cubic inches you were so proud of now do one thing COLLECT distortion.. The exact reason for med E speaker (89-93) with higher excursions and smaller surface areas. The "second wave" is controlled by phase plugs and a smaller surface area. Room treatment? Better have a plan...

So 101 on speaker building for me is know what your talking about..
My terminology may not be the as eloquent as the word salad connoisseurs, BUT my personal observation and understanding of "bass distortion" seems to conflict with most of "New way" of thinking..

FIRST; PHASE PLUGS are the ONLY way to decrease bass distortion properly on all round cone drivers "second wave". OR Don’t use cone drivers, OR Don’t use large surface area drivers.. The is NO OTHER WAY...

The reason I use smaller ribbons and planars in a bi pole NOT OB di pole, configuration. LESS distortion. If I dipole a speaker it does NOT use the same driver on the rear pole. "101 better speakers"

Now bass SPRING traps, the BEST idea so far... Distortion killers...

SECOND; Servo Bass, (primary distortion) overshoot.. control it or the distortion goes through the roof...

THIRD; Driver design, cast composite baskets and cone materials.
Construction distortion. The edges not being terminated, basket ring. LARGE, light, well cooled voice coils. Cone composite materials (shark skin). 8 ohms or more with larger cooler and lighter designs VC.

So Bla Bla Bla Bla all you want.

AND I hope everyone had a great "Passover" (3-27- 4-4) I know you did or you wouldn’t be reading this.. :-)

Regards

Thanks oldhvymec .....Interesting remarks from a great "connoisseur" in organ pipe acoustic control....

😊😊😊😊😊
There are a number of highly respected companies like Harbeth, Dynaudio, etc. who make relatively low efficiency speakers. It has been suggested on this forum that the only reason for this is to cut cost. I beg to differ. The sound characteristics of a speaker from Harbeth, as an example, is the result of very careful and meticulous selection of material, voicing decisions, and a number of other factors that have won them a loyal following (you can add me to that group). I seriously doubt that the 'only' reason for lower efficiency is cost. You can make the same argument for a number of highly respected speaker manufacturers.

I'm not sure why it's so difficult for some to understand that higher efficiency speakers do present tradeoffs, like just everything else in audio. Believe me, I would love to save some coin by buying high efficiency speakers and mate them with cheaper, flea watt amps. But I have yet to meet a high efficiency speaker that connected with me emotionally.

@fuzztone -- thank you for posting the video link. Whether you agree with it or not, the first comment below the video is by far the best explanation, and much more credible than 'oh, it's only a cost saving measure.' We should be grateful that we have so many choices that help us connect with our music in a way that makes sense to us, regardless of the underlying designs.
@oldhvymec 
[My terminology may not be the as eloquent as the word salad connoisseurs]

I think you're being too humble. I, for one, enjoy reading your posts. You have a way with words and a narrative style that's quite eloquent and a breath of fresh air. 

The sound characteristics of a speaker from Harbeth, as an example, is the result of very careful and meticulous selection of material, voicing decisions, and a number of other factors that have won them a loyal following
It is just marketing terms:) If you look to some pro audio drivers,they are better built,don't have plastic baskets as harbeths and cheap highs
Actually I had harbeth and dynaudio speakers.Harbeth speakers are limited sounding speakers.With some music (few or one instrument or solo vocals)I loved it.Try listen louder them or in free space ,outside house and their sound is very strange.Dynaudio wins here.Full range sound.They can rock here,but they are not dynamic as high efficiency speakers
Big efficient drivers makes midrange sound massive with visceral impact of instruments,some may refer them as shouty.