I have seen worse... begin sold as good.
Anyway that looks like a JBL 2405 dia.
The 2404 was sold with both 2402 and 2405 dia's.
I have seen worse... begin sold as good.
Anyway that looks like a JBL 2405 dia.
The 2404 was sold with both 2402 and 2405 dia's.
Johnny Haugen Sørgård
The pictures posted by Isak show that there is no guide pin for the diaphragm.Well the bargain I got from ebay turned out to be dissapointing. This is what the diaphragm looked like and this was supposed to be the good one:
I wonder whether the genuine 077/2405 should has two guide pins? My Frankenstein 2405 from ebay has two guide pins. I suspect that my Ebay's 2405 might be just a 2402 alnoco being assemblied to the 2405 phase plug and horn flare.
I am not certain, but I believe all of the older ring radiators had guide pins and later they were phased out to make diaphragm installation easier to adjust.Originally Posted by juud
Widget
Judging by the markings, i'd say it is a real JBL diaphragm and was installed by a JBL Factory Service center, since they almost always hand-write the date of installation on the diaphragm or recone kit. Often, the tech will mark the service center name and the tech's initials, if space permits.
That is a 2405 diaphragm, judging by the width of the moving diaphragm and the width of the inner and outer mounting rings.
Well the bargain I got from ebay turned out to be dissapointing. This is what the diaphragm looked like and this was supposed to be the good one:
Is it aftermarket or original and if so what type?
Looks like I will have to get 3 new ones
A 2405 and a 2402 diaphragm. So what is an 076?
If we knew what the hell we were doing, we wouldn't call it research would we.
The 076 looks to be just a combination of the two.
If we knew what the hell we were doing, we wouldn't call it research would we.
Can you accurately measure the thickness of the 3 diaphrams?? You can see the compliance in the 2402 I wonder if the 2403 uses the same form as the 2402 but with a thinner diaphram thickness??
Rob
"I could be arguing in my spare time"
Hey, some great new info here , many thanks !!!
Btw, nice sectional-slicing of those diaphragms !
Neato set of pics
cheers <
... the most illuminating 240x physical comparison I've seen to date.
Thanks for taking the time to do the work and post the pics!
With a recently calibrated L.S.Starrett double ball tipped micrometer, all three diaphragms shown in the previous pictures measure right at 0.0020" to 0.0021". No more speculation.
I have to say that pinching an NOS 076 diaphragm between two 0.200" balls almost made me nervous, almost.
If we knew what the hell we were doing, we wouldn't call it research would we.
Great pictures! Thank you!
Rob, maybe you could post them in the ring radiator transducteur info thread?
(by the way Rob, thanks a lot for what you posted in that section recently, especially the 2123H data!!)
what a nice work, and lot of info for all JBL "ring radiator" fans.
I have a pair of old 077-alnico drivers. Unfortunately I have to replace diaphragm to one of the driver. Unfortunately only D16R2405 (gold-gold ring dia is possible to get, not blue-blue rings).
Here are responses. I put Beyma CP21F as reference.
First is ORIGINAL 077
Second 077 "motor" with D16R2405
Third Beyma CP21F
I have a pair of 077, and they have TWO guide-pins
Next up, what's inside the Factory Franken Tweeters, brand new from sealed boxs courtesy of Jeff Keel, the original purchaser/owner. Don't worry Jeff, I'll be gentle!
If we knew what the hell we were doing, we wouldn't call it research would we.
Hi folks, I recently found and scanned this 1958 article by George Augspurger. This thread seems like a good place for it.
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