Many drivers out there had to be reconed (or re-foamed) with different recone kit (or re-foam kit) than the original stuff, for reasons of availability, cost, etc. I don't recall seeing something written on this matter with some science, like actual measurements done, or experience in the field described after job done, and comparison with the original's sound and/or specs, particularly T/S parameters. It would be interesting to know what fellow members have to say about this in terms of sound and/or measured specs. Some measurements are relatively simple, like Re Voice coil resistance or Fs Free air driver resonance, while others are more complicated to do. Big sound difference ? Large deviations in specs ? Please jump in and let me know your comments or experiences.

Here's a specific example (many others possible) from another thread with regards to a JBL driver:

Out of curiosity, why 2225H (recones) on E-140 frames for the 4520 ? Why not E-140 recones ? Or 2225H recones on 2225 frames ? Only thing available/on hand ? Cheapest solution (money, ya that bugger)? For the longer cone travel of 2225 (5mm) VS E-140 (3.56mm)? For the smaller .17 Qts of the E-140 (closer to 2205 Qts of .21) compared to 2225's .28 Qts ? Since there's a lot of other "hybrids" out there (e.g. 2205 reconed with 2225), I have always wondered what happens in these cases to driver specs T/S parameters, a mix of both ? And how does the driver reacts in the box: acoustically like a 2225H but electrically like a E-140 ? A mix of both ?

Richard