Anyone familiar with the Manger driver?

These distortions, unlike simple harmonics, are non-mathematically correlated, and occur in time AFTER the musical signal

Quite so. However, and apparently, these can be modelled -- but only with reference to electromechanical properties in each specific application. Unfortunately, I can't find a ref you may be interested in.

BTW, a simple experiment with very hard cone material coupled to powerful electromagnetic support, may reveal an "overdamping" effect (i.e. relative spl drops faster than projected -- further i.e., what we call "decay" is truncated, becoming "sub-audible" if I may coin the ugly word).

A very interesting viewpoint, Martin.

OK, This is an update on my MANGER adventures.

I've put my money where my mouth is. It will take a number of weeks for me to actually get my hands on the pair I found, but the ball is rolling. I'll post specifics of the construction of test boxes, and choice of vintage piston drivers that may be a good demonstration of "bad cones". Then will follow details on the testing protocol for waveform fidelity. I plan to use an arbitrary waveform generator making music-like percussive impulses. Departures from ideal decay profiles as provided by the generator will be considered distortion that is added by the driver based on available damping factor, modified with series impedance added inline with the drivers. I may try to use several "full range" drivers to avoid loading effects of passive filter networks. Later, I will use this same setup to test for gamma (Bl/Mms(d))requirements in subwoofer drivers.

Stay tuned!

I hope you test on open baffle and measure below or at 30ms.
Of course, without interpolating passive components. Since you're using a generator, limit the bandwidth if necessary.

What a gorgeous thread to join for I´ve been playing my Manger 103 Zerobox for many years now driven by tube amps.
My ears feel content so far, let´s wait and see what the instruments at the svoboda labs will find out.

I have been playing the manger drivers in a pair of Medea's, they need time to break in, took over a ytwo years, and theyy also need fast amps, as well as powerful one's, they are reasonably efficient, but seem to really thrive on power.