I was curious to see how a compression driver would work with a 6.5" hifi mid. This one is a modified Vifa C17 which is a cheap but decent midbass. It's box sits sideways for closer driver spacing and the compression driver (B&C DE250) is mounted to a matching 90 degree oblate spheroid waveguide. I configured a simple active crossover at 2k, used a single broad PEQ cut filter at 4k and fired them up for a listen. The result is an obvious improvement over the Vifa D19 dome tweeter, even though the crossover has had less attention. Imaging is better and the sound is cleaner.