There appears to be confusion between full range single driver speakers versus Coaxial / dual-concentric driver speakers.
Tannoy is dual concentric and Kef employs a coincident driver. Both are examples of Coaxial speakers and both (examples given above) employ crossovers.
Tannoy is dual concentric and Kef employs a coincident driver. Both are examples of Coaxial speakers and both (examples given above) employ crossovers.