"hybrid" reconed drivers: Sound & t/s para. Issues: Any available info ?
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
Some findings about hybrid recones
In the Thread link given to us here (Post # 2) by Ed Zepelli here are some quality related references :
Edgewound (Authorized JBL Pro reconer), Post # 69 "A D120F "kit" is no longer made because the kit to repair a D120F is the E120 recone kit which brings the model up to improved, latest specs."
Edgewound, post # 79 "... have reconed many D120Fs with the E-120 kit. The end result is a K-120." K(alnico) or E(ferrite) 120 ?? Also T/S parameters differences between the two driver versions (K/E-120). Regardless, still different than a D120F...
Ivica, Post # 123 "with JBL 2202 ( C8R2202 ) and MacKenzie 2202 kits applied to the same basket. It can be easily visible that at over 2kHz they have quite different behaviors." See link posted here for result details.
Ivica, Post # 136 "If talking about JBL 2202 recone, I have to confirm that their kit is fare, fare, fare ...,away from JBL , looking at tha cone, and the measurements confirm that."
1Audiohack, Post # 154 "...most of the failures I see with non JBL kits are 10-15 rounds of the bottom of the voice coil loose and in the bottom of the motor."
Robh3606, Post # 5 in underlined link above, says " I have done my own aftermarket measurements and had similar results to the ones posted. I see it as reason to stay away from the aftermarket kits if only because you don't know what you are getting. "
In same long Thread link from Ed, those who indicated having done a recone job with Aftermarket recone kit appear to be satisfied with sound, considering the price paid (except for Ivica re 2202):
Ian, # 138 "I mean foam rot is a much easier fix and the surround has much less impact on the T/L than the spider." T/L or T/S ? If Thiele/small, lets not forget that Vas parameter is directly linked to the Surround.
VSN, Post # 47 "looks and sounds just like a JBL to me."
Ear for Life, Post # 129: "I tried the Mackenzie 2226H recone kit last year. All I can say is that they delivers the performance!!"
Lee, Post#147 "My McKenzie recones are 5 years old and still keep on pumping some great bass. ;-)
BTW I have some 2226 Mckenzie recones and for 25% the price of the JBL unit, I get 95% of the quality."
Naturally, these last three are subjective, not scientific evaluations, but still worth mentioning. However, It looks like to the trained eye, differences with Aftermarket recone built quality compared to OEM can be seen or measured.
I also noted that when a member (Eaulive Post # 46; Lee Post # 115) disputes same voice coil for 2225 and E-140 to an Aftermarket recone Company or when the member requests new T/S specs with their cone installed then the Aftermarket recone Co. becomes silent... Generic type answers yes, but hot questions seemed to be tossed under the carpet.
I don't blame people looking for aftermarket recone kits, specially when the OEM kit is no longer available or if it sells for big money compared to driver price paid... I guess an Aftermaket kit is better than a non-working driver... OEM remains an ideal choice a few persons have mentioned and have gone that way.
The question I'm more interested in here is wether the specs (T/S) remain the same (or at least close) or not after a recone job is done with kit X (OEM or AF) into a different frame/basket, or with AF in same frame/basket . I have yet seen only one member reporting actual measured differences post-recone (Ivica, Post # 123 above, OEM VS Aftermarket, in another frame/basket). As reported by Ivica: "mine E120 basket "re-coned" with McKenzie 2202H kit " and " ... I have got JBL 2202H recone kit (C8R2202) and 'put it' into E120 basket." His frequency response curves on same graph do show differences, not only with Barry's original 2202H, but also among the two recone jobs (OEM vs Aftermarket). Ivica, Post # 10 in underlined Thread link above.
Moreover, installing a 2225 recone on a E-140 frame/basket for example would not lead to specs being as an original 2225, even at low frequencies, according to fellow member FLODSTROEM's report based on a simulation done with speaker software. Very clever ! In addition, well-informed member 4313B reports (Post # 11), in the Thread link underlined above (re Ivica, Post # 123), "An E120 core is going to generate higher Bl than the 2202A, K120, 2203A, 2203H, 124A, 124H or 2202H cores due to its increased flux density." This would seem to confirm Flodstroem's statement here about BL product impact on driver response. We'll see in his upcoming software simulation.
Richard