So I am at MECA Finals this weekend and I hear this car with a lively detailed Mid and HF range that is dynamic and all around awesome.... so after the listen I ask... yup he had ID horns, NO honk, no cupped hand around ear sound, just goodness.

 

I very much agree that they could sound great when they're "properly" set up. I have worked with all three.. from the early Waveguides, ID horns and Accuwaves. Even though my last set up are all conventional drivers, but its an experimental project to see if a car could actually image, sounds linear from low to high level, produce a dynamic sounding soundstage without an EQ, and it has proved to work quite well.. of course after numerous hours of building the right passive x-overs and dealing with energy storage issues that causes group delays etc. But recently I listen to an old customer's car with a set of Accuwave/B&C driver that was done 7-8 yrs ago, and it sounded quite good.. but a lot of tuning was involve in that system back then.

What I've seen on the TEF/ MLS analyzer with the Accuwaves are the "settling time" (MLS spectral decay) are much longer then conventional speakers (close to 3+ times at some frequencies) if those frequency are not treated or eq out, it'll sound unnatural to real bad at high level. I also found that the accuwave could produce a somewhat too narrow of a soundstage in some cars, so some attention is needed in that respect. But the accuracy of the placement of instruments and the layering is where it shines.

Compression Horns in general are very dynamic, and in the cars we are only after the dispersion control characteristic, and linearity or smooth response from "on" axis to "off" axis. But like anything there are always pros and cons.