is this the best 8" sealed back midrange ?

[Sonce]

Does Qts really mean"Qtc" with the back chamber?

is it possible to do T/S parameter based sims for such sealed back drivers? Or the values for Fs and Qts are to be understood like the final Fbox and Qbox of a sealed box?

Yes, measured Fs and Qts of a sealed back driver really are Fc and Qtc - as in sealed box (with fixed volume).

 

[Kwesi]

It's Xmax is 3mm, so don't expect too much spl down there...

That's the main issue; These drivers are optimized for high power and high air load (horn) similar like compression drivers as well as low Le(i) to decrease IMD. But not to make any relevant excursion. Of course you can force them to do so a bit, but their Bl(x), Cms(x) and Le(x) behaviour is not optimized for that because it's not the intended application.

 

[JMFahey]

What´s wrong with using speakers within ratings?

Factory ratings I might add.

Trying to use them where they already dropped , say, 6 dB or worse , not only has a power penalty but they will probably run out of excursion quickly.