Or maybe the horns exhibit HF ringing?
As for that coax, an Eminence Beta12CX and ASD1001 combo is only $105 shipped. Can anyone offer a compelling reason to get the NOS Fane/Wharfedale that I can't find any concrete specs or parameters for for $100 before shipping? That's a hard sell.
Not shooting the messenger here, I'm actually a bit curious because I've been interested in making some coax PA tops.
They "ring like a bell" unless damped. The throats are also rather crude, creating diffraction effects.
There are a lot of people that liked them 60 years ago, many still do...