Quantum 4

Introduced: 1977
Dimensions:  91 x 38 x 30 cm
Bass: 1 x 30 cm
Mids: 1 x 3,8 cm
Highs: 1 x EMIT
Suggested for amplifiers with: 30-250 Watts per channel
Frequency range: 35 Hz - 32 kHz
Crossover frequencies: 600 Hz, 4000 Hz
Suggested price (pair):  850 $

A technical sheet with crossover schematics can be seen here.

You can view a brochure of the Quantum 4 here.
page 1, page 2