That's what I would expect too. Properly equalized for treble rolloff they wouldn't sound bad at all, but adding tweeters would restore the "air" that would be missing without them.

After I posted the initial message I recalled a PE project that mentions that same thing. The published graphs in this project are also revealing. Note the measured comb filter effect on the unsmoothed freq response graph. The builder's comments are: "Several people noted that the high-frequency reproduction lacked some "life" and "air". This could be attributed to the comb filtering problems that definitely were occuring. However, this also could be a result of the high-frequency capabilities of this particular driver, it is hard to say for sure. Whatever the reason, for pure audiophile use I would consider these lines to be slightly less "refined" and "articulate" than many standard speakers.

Too bad. I really do like the concept of a full range drive line array.

• Kuze 3201 Line Array