I found a pair of 4425s a few years ago. These were untouched speakers in basically new condition. I never liked the sound of them. Bass was heavy and uncontrolled. There was a resonance in the upper midrange that was irritating and the mids were muddy at best. The first thing that I replaced were the 2416 horn drivers with 2426 drivers. Also replaced the diaphragms with Radian aluminum units. This did not tame the midrange muddiness or the obnoxious resonance. Looked for replacement woofers. The TAD/Pioneers and JBL 2206H were contenders. Got a deal on a pair of 2206Hs new in the box. Removed one connection to the LF inductor on the existing crossover to disable the Low Pass section. I built three 2nd. order Bessel Low Pass circuits at center and +/- crossover freqs. Tested each outside the boxes with the woofer wires running out the port. I don't recall which one was chosen. I also used an inductance compensating section for the new 2206H. It has a higher inductive reactance then the 2214. No box retuning. This did correct the upper midrange resonance and the midrange muddiness. Actually, these speakers sound very respectable now.

In hindsite, I don't think the 2214 was a very good choice for the high crossover frequency that the 4425 needs. That being said, I am sure GTs feet were held to the fire by management imposed cost constants on this system. Also remember, the pair of 4425s that I have are the only ones I have ever heard. The 2214s are now hanging out in the old 2206 boxes in the back room. Oh, I think the 2206H is the right driver for these speakers. What an improvement!!