Nothing wrong, the original Karlsons with the 15's had the ducts, but on the smaller models they had used slits instead of ducts. What you're doing is letting the low frequencies from the rear chamber vent into the front chamber. The exponential V shape on the front acts as a broad band resonator supposedly for the full frequency range and to get the wide dispersion. I was investigating using these for my PA system a few years back, but it seems real tough to get them to do anything below 50HZ (15" model). Freddy Iverson on the Karlson form is the one to talk to. But they were in a class of what's called a broadband resonator. HTH Bill W.