Jbl 2121 or 2122 out of ????

[more10]

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

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Interesting old thread: http://www.audioheritage.org/vbullet...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]

Speaker Exchange, http://reconingspeakers.com/, also has a few JBL original C8R2121H recone kits in stock

[FREDFLYPOGGER]

hi
need JBL C8R2121H recone kit for jbl 2121 any one have one? looking for factory replacement not aftermarket

thanks

[1audiohack]

Like these?



Barry.

[DogBox]

Like these?


Barry.

Yum! You bet! They look just like the one's I've got...still.(!) Finally going to get around to doing them and putting them into
my set-up instead of the... ahem, aftermarket ones (2122) I got instead of the real JBL ones "when you could still get them"...
I kick myself now for not just biting the bullet and getting proper cones. But from what they told me at Speaker Exchange I tend
to believe them when they told me 'how good' those particular recones were... They sound quite good...and have been for the last
9 or 10 years. Checking on the baskets, they're E-110's.
You haven't been hiding anything in storage have you Barry?

[1audiohack]

Oh I have lots of stuff hidden away.

Barry.