View Full Version : Verify 2420 diaphragms

11-20-2015, 07:47 AM
Here's the history: Quite a few tears ago, I swapped a pair of 2470 for 2420 CDs. I'd like to verify that the diaphragms are original JBLs. I tried to show the tiny bump in the diaphragm center as best as I could. There is a date etched into the block, 08-01.

11-20-2015, 07:51 AM
To me, they appear to be aftermarket. No color between screws on one side (s/b red for 2420),
definition of lines in diaphragm surround stamping appears to be poor. Maybe they're dirty and
lost the color bit, but I'd be wary. Even this pic I found, I'm not sure of, but it's closer:


11-22-2015, 12:28 PM
Thanks Grumpy, appreciate the feedback.

Doc Mark
11-22-2015, 02:20 PM
Hi, blvdre,

I compared your diaphragms to some NOS Altec #34647 diaphragms, and your surrounds are swirling the same as the Altec's, I think, whilst Grumpy's JBL diaphragms seem to be swirling in the opposite direction. Seems when asked about compatibility between these same two diaphragms, someone mentioned that difference in direction. I can look it up, if you would like, but that, and the comments that Grumpy made, make me thing that you diaphragms are, indeed, aftermarket, instead of JBL stock. Just my two cents, and of course, I could be wrong. But, I also trust what Grumpy says about such things, and would put credence on his opinions. Do your diaphragms sound good, or is there something missing, or muffled? Good luck, and God Bless!

Every Good Wish,

11-22-2015, 02:47 PM
I have NOS genuine JBL diaphragms for both 2420 and 2470. I can post pictures if you need them.

11-22-2015, 04:36 PM
Thanks all. Given the cosmetic details cited, I agree that these are aftermarket diaphragms. They sound fine, but I'm sending them down the road, so wanted to be clear on what I had (truth in advertising).

timca, if you don't mind taking the time, it might be helpful to post those pics here. It would certainly be helpful for those searching for information in the future.

11-22-2015, 06:07 PM

11-23-2015, 11:25 AM
I believe that last pic is a D16R2421 (a nice diaphragm if that's what's called for).

11-23-2015, 12:29 PM
I believe that last pic is a D16R2421 (a nice diaphragm if that's what's called for).

Hi grumpy,

I agree with You.


11-23-2015, 12:32 PM

One is D16R2470 phenolic diaphragm for 2470/2461

The other one is D16R2421 for 2420