View Full Version : Help building 2203a

12-01-2015, 02:34 PM
So far ive located 12" 12.7cm baskets,
Im looking to build 4" alnico version and for starters iam looking at the
2130a full range with alnico magnet to use with the (2204h) basket by simply
Swaping them... im looking at the specs for the 2130 and the band is listed at

1. Is the band a product of the cone or magnet. The 2203 band 30hz ~ 1 khz

12-01-2015, 03:22 PM
Im reading about magnet gap depth & tp size.
Here : http://www.audioheritage.org/vbulletin/archive/index.php/t-6585.html

Where can I find information on magnet gap depth.
Cant setting the cone height make the differences up?

12-01-2015, 05:10 PM
Found a magnet gap depth thread here : http://www.audioheritage.org/vbulletin/showthread.php?624-Gaps-and-Depths
Thanks subwoof.

2203 motor is compatible with other models.

12-01-2015, 06:58 PM
If a k120 can be morphed into a 2120 and a 2120 into a 2203 can 7 use the k and d series to make a 2203?http://www.audioheritage.org/vbulletin/archive/index.php/t-17810.html

12-03-2015, 02:20 AM
Perhaps this will save you a lot of trouble. There is NO advantage in going back to the alnico version from the ferrite version. The ferrite version had the benefit of a redesign of the magnetic gap and using SFG or symmetrical field geometry for reduced 2nd order distortion, so technically will sound and measure better given the same cone and voice coil. The Alnico version is now 50+ years old, and unless you are willing to wait a long, long time, is very hard to find as you have experienced.

If you have the 2204H frames, you'd get essentially a 2203H using a good aftermarket 2203 reconing like what is offered at Orange County Speaker (or similar reconer out your way) for $150 each plus shipping. That would save you a lot of time, effort, franken-design and hassle, especially since trying to remove a ferrite magnet assembly and alnico assembly isn't easy, nor is it easy to set up, jig, and glue on the assemblies again in a precise and aligned manner. If you were to do this, best leave it in the hands and tools of an expert like Edgewound (Upland Loudspeaker) or GordonW out of Atlanta.

If you'd truly like to have a 2203H, I know where there is a pair for sale, obviously for a price, and not mine, no affiliation. Are you a subscribing member of AudioKarma? I only refer folks if trustworthy.

The 2108 will just as hard to source, but a lot easier IMHO than trying to build something out of pieces and parts not originally designed to be a whole driver. You might get something to fit into the frame, magnet, and cone system, but measure like a 2108? Not bloody likely, IMO.

Not trying to rain on your project, but if you want the original JBL performance, you're really going to need the original drivers or close, close aftermarket recone versions of them, instead of trying to somehow come up with your own DIY versions given that EVERYTHING - frame, surround, cone, cone ribbing/profile/damping, depth, weight, adhesives for cone/voice coil, coil length, winding pattern, wire gauge, ribbon wire, position, spider, etc. all will play a role in what comes out response wise. Any minor or major variation will deviate the 2108 or 2203 away from the design center that JBL came up with, and was able to replicate consistently during manufacture.

If you are really trying to replicate a pair of 4315's, IMHO, its just a lot easier to insert "want to buy" ads and see what comes up, they are out there, and you may be able to pop some out of the woodwork / closet / garages / studios where they are silently residing.

12-03-2015, 09:55 PM
Yeah I get it
I will keep looking
I wassent aware of a jig being needed to reframe the new motors,
But being a member im sure someone has experience in doing it
And will not attempt the transition myself, it will make both us sleep
Sounder im sure.
Lol thanks.

12-04-2015, 01:12 AM
Just trying to help. Some guys on AudioKarma and here have attempted magnet assembly or recentering while the magnet is energized with varying results. IIRC, commercial OEM's or repair facility will demagnetize first, making assembly a lot easier, but still requires alignment as you can imagine, then re-magnetize.

If you want the referral to the pair of 2203H for sale, PM me here at LH.

Do you already have the cabinets?