They sound pretty good, they have their own personality. Been long time thou. (i do have a mixed "pair", 1 4 ohm and 1 8. Shoog ran a system with the FR ony version of this, search for his posts n it.
very fine sounded coaxial 2-way speaker driver, particularly in the low level aera.
Please let me know, in which vintage audio components this part was in use.