Tannoy vs Altec 604

[TWiiii]

When JBL bought Urei after Altec was in various forms of collapse, JBL needed a driver to replace the custom 604 for UREI monitor speakers. According to a book I read about the history of JBL, they said they tried Tannoy coaxes and they were inferior. Therefore, JBL had to start from scratch and develop their own 15 " co-axial speaker to replace the no longer available 604. Now the 604 had been modified by UREI to get rid of the small multi-cellar horn with a sectorial horn. There was absorption added to the throat to smooth out a throat resonance around 3 khz and a foam edge was added to the horn to control dispersion. O ther than different dispersion patterns I wonder what the problem was with the Tannoy driver at that time in history. Early 80's if I remember? I don't wish to offend anyone, just looking for answers.