It would be interesting to see if the Urei horn assemblies on the Altec
coaxial drivers really do minimize doppler modulation compared with the
original Altec horn assemblies. That was one of the arguments the Urei
guys used for the extended horns they employed.

I think they traded one problem for another. By building the horn flare out
they may have avoided modulating the HF by the 15" cone, but in so doing they
also placed a substantial acoustic mask in front of the woofer. Still, the UREI
implementation was more successful than the Altec device it replaced, with its
hard edges, sectoral dividers, & straight sides.


Scott Fraser