3 Attachment(s)
Field Guide to the JBL 10 inch Midbass driver 2121 2122 2123
One of the magical things about the 4340/41, 4343 and 4345 Monitors is the 10 inch Midbass driver. This driver helps the big woofer (15 or 18") handle just the really low notes, and keeps the horn/compression driver from having to go below its optimal range.
Here's a thread showing how Infredible redid the surrounds on a pair of those ultra-rare 2121s - http://audioheritage.org/vbulletin/showthread.php?t=3527
In an older thread, Giskard said
The 4343 uses the alnico 2121 and the 4343B uses the SFG ferrite 2121H. Both have the 4" inverted paper dust cover.
The 4344 and 4345 use the newer 2122H which has a harder 3" dust cap. It is less susceptible to break-up.
All of them use a 3-inch edgewound copper ribbon voice coil.
*****
"Isn't this inconsistent with what we would normally use above 300Hz? I would assume aluminum would be desired due to the lightness and quick response at the higher frequencies."
Sure, it just wasn't in the cards way back then. The newer 2123H uses an aluminum voice coil.
Thanks for that info, G!
One thing thats a problem for modern fans is that the original model 2121 driver is unavailable. It was replaced by the model 2122 - which is rapidly getting near impossible to find as well. You can occasionally find a replacement cone (as of May 2007) for a rebuild, but even they are in quite short supply.
Some folks have substituted the model 2123 driver - but its not equivalent, its more efficient (higher output levels), and has a different response curve that the earlier 2 drivers. You'd need to re-design the crossover and, frankly, its just not the same driver.
But some folks do like it.
Thanks to Subwoof for these amazing pictures!
The Lineup up basic JBL 10 Inchs
At the bottom -
For those who can read the design specs - here's a chart Giskard has posted numerous time showing the different parameters.
2123 any good down to 100hz ?
Has anyone experience with using these over-engined and high Fs 10" drivers in satellites down to 100 hz ?
JBL has done this on the little 2 way box 4716A if I get it right. My idea is to then add a big subwoofer to end up with some sort of a triphonic system.
First Post, this seems like the best thread to bring this up in.
I have had for 35+ years two E-110 and two M12-8 in .6 sf sealed boxes and they have been the best sounding mid range Piano speakers I have ever had. They have been in my attic awaiting re-coning for 10 years. and apparently that is about 12 years past the expiration of available factory kits. I can't find any references for the M12-8 (not M112) except one line in a resource I found here that shows them to use the same kit as the E-110s which makes sense because they are Identical baskets to the eye. Now I see that there may be a glimmer of hope I can get the C8R2123H kits. or equivalent. Can anyone point me to a reliable and quality source you have got these from Or perhaps someone has 4 they need to sell. I really miss the hard hitting snap these provide. I can't get that kind of energy out of my Kappa6 and the 10W1-8s I replaced them with after they started making noise Just never had the crisp sound that the paper surrounds did.
any help or suggestions would be welcome.
