Although advises 1.2 kHz cutoff 18 dB / oct, I cut 600 Hz 24 dB / oct active filtration.
Crossover Behring, ROTEL amps.
I have couple with two lanes in FOSTEX 38 cms.
A small and inexpensive as possible amlioration: Open the back and brush the "shell" Blackson. While waiting for the Schager.
Monte enough to do without tweeter.
Sound without burrs.
Fidler serve me for many years in Hi-Fi.
CAUTION: Do not weld on the legs directemnt too fragile because of their rubber mounts that do not like this treatment!