Wayne Parham Messages: 18752 Registered: January 2001
Illuminati (33rd Degree)
While I think probably the harshness in the upper mids is probably due to acoustic issues like the interaction of reflections, be aware that a series resistor will cause some peaking. The amount of peaking depends on the crossover and on driver reactance values, but it can be quite severe. So that could be the cause. Look through the "Crossover Electronics 101" seminar handout for more information on this kind of peaking. But before looking into that, move around inside the car and listen to the sound balance. If it only sounds bad in your listening position and sounds better in others, then its an acoustic interference issue. In that case, move the tweeter location.