Originally Posted by
Don McRitchie
There shouldn't be a significant difference, if any, assuming that the throat and phase plug geometry is the same in both the ferrite and Alnico versions. I believe this is the case with the 2420/2425 and 2440/2445, but this is worth checking. Of course the big issue that will have to be checked is whether an Alnico, used for comparison, still meets the factory specs for flux density.
In bass drivers, there is a difference is sonic character because of differences in flux modulation and temperature curves of the different magnetic materials. In a compression driver, the coils are generally underhung so that flux modulation is mitigated to low levels. The lower power handling of compression drivers results in lower operating temperatures so that the temperature curve difference has minimal effect. Nonetheless, I would be interested in the results of any experiments.