Even though JBL has long since discontinued the 2231 kit and offered the 2235 as a replacement, I think it may not be ideal in some situations. I'm just trying some 2235's in my 4333's. The bass is clearly tighter with lower distortion, but the midrange is just as clearly not as good.

What the reasons are is a question. These are used 2235's that have not been tested in any way, but they look clean and seller maintains they have been lightly used. Another unknown variable is the condition of the Alnico magnets in my 2231's, although I know their history and am quite certain they have not been abused.

If you compare the published frequency response curves of the 2231 and the 2235 you will see significant differences in the range from about 600 Hz upward. The 2235 has a pretty sharp rise followed by a ragged decline, whereas the 2231 has a more gradual rise extending farther into the midrange and a smooth decline. At least, this is how the two are pictured.

With an 800 Hz crossover point those differences would be audible, I believe. Perhaps what is more important may be the measures that have been taken in designing the crossover for the 2231 which might suppress that midrange plateau. That would be exactly the wrong thing to do with the 2235. The upper range of the 2235 may not match up well with a crossover designed for the 2231, so the sound in the crossover region is being dominated by the horn. On the other hand, a crossover like the 3135 for the 4430 may have been tweaked to deal with the upper range of the 2235, but I wouldn't know how.

I would say a 2231 or 136 in a four-way, or a three-way with a lower crossover point could be reconed with the 2235 kit without hesitation. If, however, you have a 2231 in the 4333 or similar three way, and your 2231 cones are ok, and you are considering whether to refoam or recone, I would definitely suggest using the unsanctioned after market foams and keeping the original cones, based on my anecdotal experience. If your cones are gone, of course, there is no other option but to recone.

David

Edit: On reconsidering, it might have been better to put this thread in general discussion. I put it here, because I really wanted to elicit comment from anyone who might have technical information bearing on this issue.