My experience with the round 650Hz tractrix horns Edgar sells is that they need 8dB compensation above 8kHz with an Eminence PSD2002 and 12dB compensation above 4kHz with a JBL 2426.JBL 2426 on Edgar round 650Hz tractrix horn
Start EQ around 4kHz at 6dB/octave so that there's some boost at 8kHz and full augmentation at 16kHz. The collapsing DI of the tractrix horn provides some EQ, but not enough to make response flat above 8kHz with either the JBL 2426 or the Eminence PSD2002.