There is no Goodmans DT3 in this configuration and the stated frequency range is 45Hz-15,5kHz ±3dB
https://www.radiomuseum.org/r/radford_monitor.html

Radford Monitor has the following drivers:

Kef B139 6171
Goodmans mids driver (also used in Goodmans Maxim "M range" speaker)
Celestion HF1300

Auditorium and Studio models also have a super-tweeter either Telephones or Coles 4001G

https://www.radiomuseum.org/r/radford_monitor.html