...

"The series resistance will also change the TS-parameter of the tweeter maybe this makes the difference.

Also the damping factor of your amplifier reduces due the series resistance."

That is true, but frequency dependent damping factor is

also affected by the series capacitor, which has a much

higher impedance than the tweeters Rg in the crossovers

rolloff range and the crossover frequency is typically fairly

above the resonance of the tweeter.

Every circuit has to be investigated individually,

concerning the resulting Qes ... it depends on the

tweeter's properties and the whole crossover

circuit.

But it is impossible to make the tweeter "see" the

amplifier in the rolloff region of the crossover, there

will always be a high impedance in series,

with resistive component or not.

The question - besides going active - may be:

Where do we get damping ?

One option is to make Qm lower and apply mechanical

damping (e.g. by a large rear chamber and a flow

resistance behind the membrane) to the tweeter to get

the desired effective Qts.

Another option is to provide some low electrical

impedance in parallel to the tweeter especially in

the rolloff region of the crossover, which provides

some damping by back EMF. For purposes of

back EMF solely it is not important, whether the

current induced by the tweeter's moving voice coil

flows through the amplifier

("which is ideally a wire with amplification")

or through a (low) impedance parallel to the tweeter.

But you won't get that impedance very low - just

as low as possible.

If one does not want to compensate the resonant

impedance peak of the tweeter using an LCR in

parallel to the VC terminals, also a resistor

in parallel can be used to make the load more

resisitive and damping more frequency independent.

You can use that even without series resistor, which

means without padding the tweeter down ...

That will cost some efficiency ( not voltage sensitivity)

but the crossover slope will be closer to the "resistive load"

case. Especially with a tweeter of relatively high impedance

this may be an option.

Kind Regards