so Qts doesn't matter if the speaker is crossed above Fs?

[Jipolx]

Is true or not.

 

[AllenB]

It's not that it doesn't matter.. but you can use your crossover to get the response you need.

 

[stv]

... and depends how high above fs it is crossed.
Also the fs impedance peak will influence a passive crossover.

 

[GM]

Qts doesn't matter if crossed above its upper mass corner (Fhm) where T/S theory peters out:

Fhm = 2*Fs/Qts'

(Qts'): (Qts) + any added series resistance (Rs)