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bldozier
08-21-2015, 09:53 AM
Hello,
Im looking for information how to construct a 2121 or 2122a
So far ive found
Le10a
E110? Ferrite
Le111a
K110
Is this correct.
I wonder how the e110 will compare in sq.

http://www.audioheritage.org/vbulletin/showthread.php?16962-Field-Guide-to-the-JBL-10-inch-Midbass-driver-2121-2122-2123
http://www.audioheritage.org/vbulletin/showthread.php?30425-2121-vs-2123

1audiohack
08-21-2015, 10:04 AM
I am not quite sure what your question is.

The E110 basket/motor is identical to the 2121H basket, in every respect so a C8R2121 cone kit in a E110 basket becomes a proper 2121H, minus the foil cal sticker.

Is that helpful?

Barry.

bldozier
08-21-2015, 10:38 AM
With research I see the le10 is 16ohm, not usable in place of 2121 on the 3145.
The alnico version is what the questions pertained

Was unsure if the e110 was in fact ferrite.

Can you reflect if the if the k110 would be identical to the 2121 non ferrite. (A)
Brian...

1audiohack
08-21-2015, 12:01 PM
Hi Brian;

I am sorry to say that I don't have solid knowledge going that far back.

I will look some this evening.

Barry.

ivica
08-21-2015, 01:54 PM
With research I see the le10 is 16ohm, not usable in place of 2121 on the 3145.
The alnico version is what the questions pertained

Was unsure if the e110 was in fact ferrite.

Can you reflect if the if the k110 would be identical to the 2121 non ferrite. (A)
Brian...

Hi bldozier,

JBL E110 is Fe type magnet, while K110 is AlNiCo magnet. 2121 is AlNiCo magnet too, but 2121H, 2122H, 2123H are Fe-type magnet, so E110 basket can be used to recone as 2123H, 2122H...
If you have clean e110, I would suggest you to try it with 3145 prior to do reconinig, may be you will be satisfied with the sound.
May be covering its aluminum dist cap with cardboard one, can make it 'less metallic sounding'


regards
ivica

martin2395
08-21-2015, 04:11 PM
Is it even possible for a speaker to sound 'metallic' in the 300Hz-1000Hz region? Just curious.

bldozier
08-21-2015, 05:14 PM
Alright thats a rise in compatibility, so far so good.
Maybe some knows about the
K110s compatibility.
Brian.

Thanks,
Ivica.

ivica
08-21-2015, 11:38 PM
Alright thats a rise in compatibility, so far so good.
Maybe some knows about the
K110s compatibility.
Brian.

Thanks,
Ivica.

Hi

K110 can be used as E110 too, but as it has AlNiCo magnet motor, the problem of it "magnet strength" can be a problem, as may be has to be re-magnetized.

regards
ivica

more10
08-23-2015, 03:14 AM
Hopefully the recone kit is still available : http://www.jblproservice.com/pdf/Goes%20Into%20List/Goes%20Into%20List.pdf

The combination is not listed, http://www.audioheritage.org/vbulletin/showthread.php?7850-E140-2225&highlight=Recone+Basket+list

more10
08-23-2015, 03:21 AM
Interesting old thread: http://www.audioheritage.org/vbulletin/showthread.php?16962-Field-Guide-to-the-JBL-10-inch-Midbass-driver-2121-2122-2123

more10
08-23-2015, 03:22 AM
This is also interesting http://www.audioheritage.org/vbulletin/showthread.php?30425-2121-vs-2123

Mike Caldwell
08-24-2015, 05:49 AM
Somewhere I remember reading that the K110 had a tighter voice coil gap than the E110 making alignment of a new recone kit in an old K series frame tricky at best.

more10
08-26-2015, 02:22 AM
The only 2121 replacement cones I found was at Orange County, including reconing: http://www.speakerrepair.com/page/RECNEPRC.html

Anyone got experience with "OCS parts" cones? Half the price and probably made in US :-)

Mårten

1audiohack
08-26-2015, 06:03 AM
Jbl had them (C8R2121) on the shelf last month, I bought eight.

I will check and see if they still have shelf stock if you are interested.

Barry.

more10
08-26-2015, 06:54 AM
Jbl had them (C8R2121) on the shelf last month, I bought eight.

I will check and see if they still have shelf stock if you are interested.

Barry.

I am interested in two, depending on price of course. PM me.

more10
08-26-2015, 01:23 PM
I was a bit curious about the different cones, maybe one could reuse the E/K110 cones in a 2121H build, just replacing the surround and the dustcap? So I had a look into the Thiele-Small parameters.


MODEL FS QTS QMS QES VAS EFF PE XMAX RE LE SD BI MMS FLUX
2121 35 0.19 5.5 0.2 110.4 2.7 75 1.52 6.8 0.9 0.032 12.7 25 1
2121H 35 0.16 5.5 0.17 110.4 2.7 75 1.52 6 0.8 0.032 13.7 26 1.02
2122H 40 0.23 1.9 0.26 65.1 2.4 100 3.05 5.8 0.6 0.032 13.2 28 1.02
2123H 85 0.32 2.5 0.37 19.8 3.5 250 2.54 4.2 0.4 0.032 13 25 1.07
E110 65 0.36 4 0.4 45.3 3 75 2.54 6 0.4 0.032 12.1 21 1.03
K110 65 0.36 4 0.4 45.3 3 75 1.52 6 0.4 0.032 10.3 17 1.02

Flux is about the same for all drivers. Since the alnico magnets probably are weaker, the gap is probably a bit narrower.

MMS is about the same, could the cone itself be the same for all drivers?

Bl is about the same. They all have about equal number of coil turns in the gap.

Xmax differs a lot. Different voice coils in different drivers. K110 is close to 2121(H). Is E110 correct?

Pe and Eff is close between 2121 and K110.

Vas differs a lot. Must be the surround. 2121 has soft surround. E/K110 has cloth surround. Spiders?

Qes differs too much. I don't believe Qes can be changed by replacing the surround. Or maybe the spec sheet is wrong? It has happened before :-)

Qms is pretty close. Softer surround should get higher Qms, right?

Fs differs a lot. Softer surround should give lower fs.

Model differs a lot. Can be fixed with foilcal :-)

I will try to convert a pair of E110, replacing the surround and the dust cap.

Mårten

more10
08-26-2015, 01:28 PM
Interesting old thread: http://www.audioheritage.org/vbulletin/showthread.php?16962-Field-Guide-to-the-JBL-10-inch-Midbass-driver-2121-2122-2123



The voice coil and spider on the E110 looks just like the 2121 pictured, VC is 0.300" tall, the cone is only 0.014" thick. By comparison the 2123's VC is 0.440" tall and the cone is about 0.024" thick. I don't have a 2122 kit to look at.

I believe converting an E110 to a 2121H by replacing the surround and he dustcap is doable. I really don't like ruining working cones.

more10
08-26-2015, 10:25 PM
Speaker Exchange, http://reconingspeakers.com/, also has a few JBL original C8R2121H recone kits in stock

FREDFLYPOGGER
03-13-2017, 02:19 PM
hi
need JBL C8R2121H recone kit for jbl 2121 any one have one? looking for factory replacement not aftermarketthanks

1audiohack
03-23-2017, 08:41 AM
Like these? :D

764137641476415

Barry.