Yeah, but the diaphram is in the driver, not the horn. I can see that trying to push 200Hz into my 806A drivers that are rated for 500Hz might create problems. But putting 500Hz through a driver that's rated to 500Hz, but blowing through a horn "rated" and 800Hz, is a different animal.

The question is what happens to the 500Hz signal from an 806A driver when it goes through an 811B horns?

Here's the scenio: I have two 806A compression drivers (rated down to 500Hz). One is bolted to an 811B horn (rated at 800Hz), the other to a 511B (rated to 500Hz). I put the same 500Hz signal through both. The 806As are supplying the signal equally..yes? What happens to the signal as it goes through the horn and what SPL comes out the business end? I assume the 811B will produce a lower dB level at 500Hz than the 511B. If so, how much lower and do I really care?