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Thread: Building a "2203" from misc parts

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    Building a "2203" from misc parts

    I know this topic (i.e. compiling 2203 equivalents from assorted factory and aftermarket parts due to JBL cone kits no longer being available) has been discussed in multiple threads, but I can't find any clear conclusions/solutions.

    The main obstacle seems to be finding spiders with the correct compliance. (Donors for baskets and cone/VC assemblies are plentiful, mass rings can still be ordered, and appropriate aftermarket foam is available - correct me if I'm wrong.) It has been proposed to cut stiffer spiders to losen them up, but according to the expertise this is a questionable method WRT durability. Another proposal was to search for aftermarket spiders. Did anyone have success here?

    It would be very nice if we could arrive at a BOM here (and possibly some hints for DIY:ers who are brave enough to attempt such major surgery...).

    (Background: While searching high and low for another 2311 for my Baby S22 project, I by chance found a reconer who claims to have spiders for 2203/2231. "I have it. I'm the only one who has it!" Of course I'll follow up this lead but I wonder what it could be - aftermarket stuff or NOS? Did JBL ever sell this item separately? Could he possibly have bought parts directly from the OEM plant?)
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    Senior Moment Member Oldmics's Avatar
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    So a foam surround installed on a 2204 kit won"t work?


    Oldmics

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    Nope, the 2204 has a different cone, coil and spider. I think it would be a great driver to try in a mini S22 though. Just add subs for VLF.

    I wonder how a 124/2203 cone/coil/surround would behave with the "better" 2235 spider.

    JBL has plenty of 121 recone kits, which are identical to the 124/2203 except for the mass ring and spider.

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    To my understanding (I'd probably better wait for gurus to elaborate on this, but here goes anyway...), replacing the edge alone will not yield a high enough compliance - a softer spider is called for (in additon to said mass ring). Furthermore, now when looking closer at the datasheet, I realize that the VCs are significantly different (magnets and pole pieces are the same for 2203 & 2204, right?), which of course may be fine in some applications. (If one is hell bent on creating a clone - would it be possible to move the VC from a 2231 moving assembly on death row? :shock: )
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    Oops, the guru beat me to it.
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    Recipe, v0.1

    Ok, so here's the preferred recipe so far then:

    Basket:
    2202, 2203 (obviously), 2204

    Cone, VC, surround:
    C8R121A/H (I don't find this in the price lists I have, though.)

    Mass ring:
    35 g

    Spider:
    Well, that's the question...
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  7. #7
    Senior Member GordonW's Avatar
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    I just compared the T/S parameters of the 2235 to the 124A... the 2235 spider is NOT a good match. The 124 spider is SOFTER (ie LESS stiff) than even the 2235 spider!

    All is not lost, though... there is an aftermarket spider even softer than that specified for the 2235, IIRC. Aftermarket spiders are usually rated in a scale of A to E, where A is extremely soft (low stiffness) and E is VERY stiff. The 2235 spider, in aftermarket parlance, is a "C" stiffness, IIRC... and there is another spider available in the same size that is a "B" stiffness. Also, there are a couple of Gauss replacement parts, that are even softer spiders (close to an aftermarket "A" stiffness), should that be necessary, upon results of testing.

    Giskard, any further thoughts on sending me a dead 121 or 124 cone assembly, so I can look for suitable aftermarket parts to build up a 124 kit? I'd be glad to try and locate something suitable... it'd be a way to put this spider question to rest once and for all, too...

    BTW: I was just playing around with the parameters of the 124A in a box modelling program. Has anyone tried one of these guys in about 2 cubic feet with a passive radiator? I modelled one with a PR of the same area and stiffness of the 124A, with about 4 times the cone mass of the 124A (14 ounces). With a 60Hz crossover, it'd have bass WAY down into the low 20s, with a predicted output capacity of OVER 105 dB (more than THX spec!) down into the mid 20s, in a moderate-size room...

    Regards,
    Gordon.
    This Is Gordon's Page: www.geocities.com/gordonwaters

  8. #8
    Senior Member GordonW's Avatar
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    As for the 2204 into 2203 thing... I checked, and there wouldn't be MUCH DIFFERENCE between a modified 2204 and a 2203. With the 35 gram mass ring added to the 2204 cone assembly (which is about 57 grams stock), it'd be within 5 grams of that of a 2203 (which is about 97 grams stock). Add another 5 grams (easy enough, just spray a bit of lacquer or shellac on the backside of the cone before installing the kit, it'll also stiffen it up a bit) to the 2204 cone, it'd be dead on (very close to 97 grams).

    The 2204 also has the SAME Xmax as the 2203 (well, it's the difference between 6.9 mm and 7mm), which indicated pretty much the SAME voice coil... change out the spider and surround, and you'd have something that should, at least as a subwoofer, perform exactly like a 2203. It'd have to be measured, to see if it'd compare on the high end... but given the similarity of cone geometry, texture (both ribbed cones) and motor, it'd be hard to imagine it being much different.

    Regards,
    Gordon.
    This Is Gordon's Page: www.geocities.com/gordonwaters

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    Gordon, thanks much for explaining the aftermarket spider rating system. I'll try to brain pick my contact, but he might be unwilling to reveal this info.

    Regarding 2203 vs 2204 VCs: While winding heights are close, the former has a higher number of turns, as evident from the differences in Le and BL (1.4 vs 0.7 mH, 21 vs 15 Tm). Thus, I figure the approach you describe will produce a very fine VLF driver, but it will not be a drop in replacement for the 2203. It's tempting to give this a try, though. (I know where to find some 2204s at decent prices, and now when I've met this competent reconer... )
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    Another aspect

    Several posts in this forum indicate that the 2203 is somewhat ill-behaved in the higher frequency range. The (ridiculously LP-filtered) FR graph in the data sheet indeed shows two peaks in the 800 - 2000 Hz range, as opposed to that of the 2231, which is smooth in that range. If the objective is to build something "2203-ish" rather than a copy, perhaps this could be addressed (possibly by sacrifying some low end capabilities)? Maybe even the above discussed 2204 route is a step in that direction?

    (It could be, though, that such an effort is in vain, given the 2214. This is the driver Mr. Widget suggested I use for the mini S22, and I'll follow his recommendation. Being able to take the crossover up to 1200 Hz if needed (to reduce the "honk" I anticipate from the 2311 crossed at 500 or 800...) is a big plus here. It's just that 4" VCs are so cool and 2203s so good looking...)
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    If I were to build a 12-inch based "S22" today I would try the 2204H. Put it in something like a 2.0 cubic foot volume tuned to 50 Hz and let it rip. It has greater efficiency and impact than the 2203H for that type of system. My opinion is the 136H/2231H had the minimum efficiency required (and the LE14H and 124H/2203H are just too inefficient) for use in that system.

    The 2214H is a baby compared to the 2202H, 2203H or 2204H.

  12. #12
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    Quote Originally Posted by GordonW
    I just compared the T/S parameters of the 2235 to the 124A... the 2235 spider is NOT a good match. The 124 spider is SOFTER (ie LESS stiff) than even the 2235 spider!

    All is not lost, though... there is an aftermarket spider even softer than that specified for the 2235, IIRC. Aftermarket spiders are usually rated in a scale of A to E, where A is extremely soft (low stiffness) and E is VERY stiff. The 2235 spider, in aftermarket parlance, is a "C" stiffness, IIRC... and there is another spider available in the same size that is a "B" stiffness. Also, there are a couple of Gauss replacement parts, that are even softer spiders (close to an aftermarket "A" stiffness), should that be necessary, upon results of testing.

    Giskard, any further thoughts on sending me a dead 121 or 124 cone assembly, so I can look for suitable aftermarket parts to build up a 124 kit? I'd be glad to try and locate something suitable... it'd be a way to put this spider question to rest once and for all, too...

    BTW: I was just playing around with the parameters of the 124A in a box modelling program. Has anyone tried one of these guys in about 2 cubic feet with a passive radiator? I modelled one with a PR of the same area and stiffness of the 124A, with about 4 times the cone mass of the 124A (14 ounces). With a 60Hz crossover, it'd have bass WAY down into the low 20s, with a predicted output capacity of OVER 105 dB (more than THX spec!) down into the mid 20s, in a moderate-size room...

    Regards,
    Gordon.
    As far as JBL can remember all the 12-inch spiders were the same, even the original 121 (which is why I originally thought there would be no problem using the 121 kit with the 124/136/2203/2231/2235 mass ring). JBL went to a much stiffer spider in later 121's to deal more effectively with the 100 gram mass ring. The remaining 121 recone kits all have the stiff spider. I recently reconed a pair of 121's and noted that the spider was indeed very stiff. The 121 and 124 cones I had must have gotten pitched because I can't find them to send to you.

    Yes, I played around with both the 124/2203 and 136/2231 with the PR15C back in the day such things were popular and they were quite fun. Neither ever had any trouble dumping serious VLF.

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    Info from the reconer

    Quote Originally Posted by lfh
    Gordon, thanks much for explaining the aftermarket spider rating system. I'll try to brain pick my contact, but he might be unwilling to reveal this info.
    I just talked to him, and here's what he says:

    When ordering separate aftermarket parts (cones, spiders etc), everything but the VCs are from the OEM factories JBL uses. He didn't elaborate on the non-availability of JBL VCs. (Perhaps JBL makes them in-house or a potential OEM factory has signed agreements not to make them available to third parties?) According to him, some high quality aftermarket kits are 100% correct except for the VC, which may or may not be close enough. He strongly recommends using JBL VCs only, which indicates he's serious about his craft. As for spiders he has "JBL" (OEM) parts, but he can't order a "2203" spider - experimentation as described by Gordon is called for. He has a "soft" one he thinks suits this application, but that was as much info I got. It seems it's up to us forum members to figure out the "missing ingredient".
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    Mini S22 interlude

    Quote Originally Posted by Giskard
    If I were to build a 12-inch based "S22" today I would try the 2204H. Put it in something like a 2.0 cubic foot volume tuned to 50 Hz and let it rip. It has greater efficiency and impact than the 2203H for that type of system. My opinion is the 136H/2231H had the minimum efficiency required (and the LE14H and 124H/2203H are just too inefficient) for use in that system.

    The 2214H is a baby compared to the 2202H, 2203H or 2204H.
    Giskard, I really appreciate your help on this! Reflecting that I'll bi-amp the system and it'll "never" see the other side of 90 dB or so (picky neighbours and thin walls...), the design considerations are a bit unusual, though. Furthermore, a sub (or 4-way for that matter) is not desired due to space limitations, so the 2204 is not an option IMHO, whereas I figure 2214 would be feasible in this context.

    However, thanks to this reconer I can get pretty much what I want - 2203A, 2203H, 2214H, and hybrids including "trick" stuff such as a cut-down LE14 cone in a 220x basket! My head is almost spinning... BTW, I'll ask the reconer about availability of the parts, should other forumites be interested.

    Given this fantastic range of choices, and the target frequency range is "reasonable" VLF to "very good" 800 Hz (and optionally "decent" 1200 Hz), what is then the most promising route? My first thought was 2203H, but if I've understood correctly, it's not really good up to 800 Hz?

    Since I didn't buy the 4343s, I have allocated myself a small R&D budget. Thus, I'm prepared to try out some combinations (I already have the 2214s, but they need new foam and possibly spiders), but of course the fewer iterations the better. A 2214 vs (custom) 4" shootout would be fun though, so one more candidate is needed!
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  15. #15
    Senior Member GordonW's Avatar
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    Man, now THAT'S an interesting idea... a cut-down LE14 cone, with a 2235 or 2204 voice coil and a 2235 mass ring (or maybe not, it might not NEED the mass ring), with a 122A/128H surround and an 'A' stiffness spider, in a 2204 basket.

    That could be one of the lowest-distortion 12s ever devised...

    BTW- I'm going to be getting a couple of "derelict" aftermarket 2204 cone assemblies, from a pair of drivers that's going to be reconed (their suspensions have been worn out and one has a bad lead-in wire, that's the only things wrong with them)... if I can find a suitable basket (I think there's an E120 basket around I can tinker with), I may try installing one of the Gauss spiders I have and a 128H surround. Then, I can experiment with mass rings and such...

    As for voice coils- well, I've seen some not-so-good, and some VERY good aftermarket voice coils. As in, some are good enough, to pass visual inspection (no voids, no crooked windings etc, and having the proper edge-wound wire and dimensions) and to TEST exactly as the originals, on LEAP/LMS. I'd not rule out aftermarket voice coils, per se. Some of the better ones are even using the fiberglass-reinforced formers now... THOSE are some STOUT voice coils...

    Regards,
    Gordon.
    This Is Gordon's Page: www.geocities.com/gordonwaters

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