They have a hollow grainy sound up to 9 or 10 feet after that this effect goes away.I haven't measured them but I will soon is this caused by the comb effect.Or maybe high frequency breakup I am using them to 6000Hz.regards
Taking a wild guess is that you need to cut one of them down crossover frequency wise. I would run one of them at around approx 800hz and see if that helps. Just a simple coil @ 1st order.