I am starting this thread because of an OT post in another thread that I think is very important and I am not sure it has been properly addressed before.
If we DIYers are not using the moderately priced B&C, Beyma, or BMS drivers, we frequently are using second hand drivers or "new" drivers sourced from eBay. This is reasonable... especially if you want 375s or 2441s or any other vintage JBL as buying them new from JBL would be rather difficult.
The problem is that loudspeaker drivers are precision instruments and compression drivers require particularly tight tolerances. Having bought secondhand drivers and even those with recently replaced diaphragms with factory fresh replacements... the results are not always up to spec. Especially if the person doing the work is inexperienced. The quote below has been edited to only discuss this topic, but I think you'll get the idea.
The point I'm trying to make is that buying a secondhand compression driver is a real crap shoot... I have measured dozens and it is rare that a secondhand pair are within several dB of each other or even their specifications... new drivers purchased through "normal" channels will be within a dB or two of each other and have the specified harmonic distortion levels...
My recommendation is to use new drivers when possible and with vintage gear either work with a top flight repair center or send them back to the factory... we've discussed red wax seals before, but simply screwing in a pair of new diaphragms isn't all there is to factory spec either.
Widget