Building a "2203" from misc parts

[lfh]

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?)

[Oldmics]

So a foam surround installed on a 2204 kit won"t work?


Oldmics

[4313B]

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.

[lfh]

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: )

[lfh]

Oops, the guru beat me to it.

[lfh]

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...

[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.