Originally Posted by
mech986
No, 2405 cannot work with the N1200. The 2405 crosses over at 8000hz with the 4315 crossover network. The N1200 crosses at a much lower 1200hz and is meant to be used with the 175DLH compression driver which has a larger diaphragm and designed to play down towards that lower area. The N1200 would allow too much lower and upper midrange energy to get to the diaphragm which would lead to damaging the 2405 diaphragm.
If you want to experiment, sure getting an extra pair of 2405's with the correct and original JBL OEM diaphragms could be a reasonably cost effective way to obtain two JBL diaphragms. You could then swap in the spare pair and see if the problem still resides with the crossover, or you could see if one pair of the 4 four drivers complementary matches the issue with the crossover to even out the high frequencies. The 2405 has plenty of additional output available if the L-pads are working properly so you should be able to get all the HF sizzle / output you want. Otherwise, it would be a good idea to clean the L-pads with DeOxit or similar contact / potentiometer cleaner and exercise the controls about 40 times each. If that doesn't clean the uneven output issue, then one should look into replacing the capacitors and resistors with new. We can discuss parts options if it comes to that.