> Many tweeter designs do not have horns, but they do not need the
> control, as it is designed in.

Why do you say this?

Hi GarMan.
Not everyone attenuates the HF horn with an L-pad.

If the system is passive/all subsystems running off the same amplifier, then the l-pad is used to match the sensitivity of the HF horn to match that of the woofer (which should also be of a high efficiency design). If the woofer is horn loaded then it may not be necessary to include the l-pad, or at least the attenuation would be a lot less than 15db. High efficiency woofers as direct radiators still only reach around 98db 1w/1m whilst horn loading them will get you much closer to the ~110db 1w/1m of the HF horn.

As Dean mentioned the flare also provides directional control, a big benefit of using a horn. It will also alter the frequency response curve and the horn can be designed to boost output on-axis such as a radial horn, or do other things too.

Even though the horn may be attenuated you maintain the dynamic range of the device being another positive.

If the system is bi-amped then output levels are matched with the amplifier and not attenuation circuits.

Adrian