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View Full Version : 2417 vs. 2416: same magnet, just different diaphragms?



Rudy Kleimann
11-14-2009, 10:44 AM
What is the difference between these? I know a 2417H diaphragm fits the 2416H, but does it then become a 2417H or is it something different?

I have a pair of SR4722A with the 2417H driver and baby-butt horns that I bought used. One of them didn't sound right, so I pulled the diaphragm and discovered that it must've "got drunk" on one of its' previous gigs. The diaphragm appears fine, but there was a little zinc oxidation (the magnet plates are zinc electroplated to prevent rust) in the magnet gap and slight corrosion pitting on the phase plug.

I have several good 2416H magnets laying around, and would like to use one to replace this. I am almost certain the magnets/phase plugs are identical, but would like to confirm this. Anybody out there able to positively confirm or deny this?

PS- I know that some early 2416H's had 6-7 holes instead of annular slits through the phase plugs. All of my 2416's have the annular slit phase plugs, as do my 2417's. This is what inclines me to believe that the only difference beteween (later) 2416's and (all) 2417's is the diaphragm. And, of course, the right crossover/filter netwrok to achieve proper frequency response, meaning the right driver in the right cabinet with the right network.

SMKSoundPro
11-14-2009, 01:57 PM
Hi Rudy!

The driver will be a 2416 with a 2416 phragm, and a 2417 with a 2417 phragm.

i have the exact same thing here, SR4722a with 2416 phragms. I know the chart says to use a 2417, but it is what I had for the day to get me out of woodwork.

I have a 2416 driver magnet assembly taken apart at work and see where the 2416 and 17 are the exact same motor. i then took a 2416 and sliced the diaphragm off of the black plastic mounting ring. I did this with both a 2416 and 2417 diaphragm. The 2416 "tin" in much thicker than the '17. I did not measure it with the micrometer, and still have them at work so maybe I will. The difference in thickness of the '16 dome lends me to believe that it can be played lower and pushed a bit harder before shattering. It is really a very tough titanium sheet. The '17 was very much thinner and more delicate to hold in my hands.

I will do my best to make some measurements and post the info and pics asap.

Hope this helps.

If the pole piece of the drive has salt shaker holes then it is identified as a 2415.

Scotty.

Rudy Kleimann
11-15-2009, 09:27 AM
Yes you are absolutely right about the thin-ness of the 2417H diaphragm. The SR Series II catalog touts this driver as (from memory) "having the lightest diaphragm ever produced for this driver, adding 5dB greater HF output over previous drivers."

The diaphragm may in fact be the only difference between the 2416 and the 2417 driver. I'd just like to confirm it. I don't want to discover over time that my pair of 4722's don't sound like a pair due to the wrong motor.

Regarding 2415 vs 2416, you're "sorta" right, depending on who you ask. Except for where JBL sold (or a couple of forum members have seen) 2415-equipped phase plug motors in speakers that were marketed and listed as having 2416 drivers in them. I saw "2416" drivers FS on ePay a few years ago and they had the "salt shaker" style phase plugs a la 2415's. I had never seen such motors from JBL, and couldn't believe it was a JBL product. I posted about it here on the forum and emailed pics to JBL PRO at the same time. Several experienced JBL FASC guys here on the Forum identified them as 2415's, and suggested that since the magnet (motors) aren't marked, look the same from the outside, and that 2415, 2416, and 2417 motors and diaphragms all will interchange, that it was an easy error in assumption to make. The reply I got from JBL Pro Service was "These must be another brand; noone here recognizes these drivers as JBL product." I posted this reply from JBL Pro Service on the forum and asked "WTF?" and Forum members here suggested that the guy at JBL may have not been around long enough to have seen the 2415's uncovered, and that, after all, JBL has made SO many different drivers over the years... Bottom line was I passed on the 2416/2415 ePay auction.

subwoof
11-15-2009, 10:29 AM
the 2417 motor has a shiny plate on the back half of the magnet sandwich and it's outside edge is beveled. easy to spot.

sub

Rudy Kleimann
11-15-2009, 10:38 AM
Thanks, subwoof.

Do you know if this is simply cosmetic, or a significant indicator that the motor is different where it counts, i.e. gap, magnet, or phase plug?

Predrag Dukic
11-19-2013, 03:55 AM
Hi Rudy!

The driver will be a 2416 with a 2416 phragm, and a 2417 with a 2417 phragm.

i have the exact same thing here, SR4722a with 2416 phragms. I know the chart says to use a 2417, but it is what I had for the day to get me out of woodwork.

I have a 2416 driver magnet assembly taken apart at work and see where the 2416 and 17 are the exact same motor. i then took a 2416 and sliced the diaphragm off of the black plastic mounting ring. I did this with both a 2416 and 2417 diaphragm. The 2416 "tin" in much thicker than the '17. I did not measure it with the micrometer, and still have them at work so maybe I will. The difference in thickness of the '16 dome lends me to believe that it can be played lower and pushed a bit harder before shattering. It is really a very tough titanium sheet. The '17 was very much thinner and more delicate to hold in my hands.

I will do my best to make some measurements and post the info and pics asap.

Hope this helps.

If the pole piece of the drive has salt shaker holes then it is identified as a 2415.

Scotty.

Do You have exact measures? Weights and thicknesses?

Rudy Kleimann
11-20-2013, 04:06 PM
Well, since I last posted on this old thread, I have learned a couple of things about the differences:

The 2417 phase plug is set at a different height than the 2415 and 2416 phase plugs, with respect to the diaphragm mounting surface.
Put a 2417 diaphragm on a 2416 and the dome hits the phase plug before the diaphragms' mounting ring contacts the mounting surface of a 2415 or 2416.
Conversely, a 2416 diaphragm mounting ring will seat on the mounting surface of a 2417 motor, but the space between the 2417 diaphragm's dome and the 2415/2416 phase plug is much greater -too much.
You can prove this by placing a (dead diaphragm you don't mind wrinkling) 2420, 2421, or 2425 diaphragm on the 2416 or 2417 motor and pushing down on the dome to gauge the air gap under it between the diaphragm and the phase plug. On the 2415 or 2416, it feels normal ~.050" but on the 2417 the gap is MUCH more.

Here's a tip: Buy a Radian #1225-8 or -16 (replacement for the JBL 242x) and the Radian back cap kit to replace a JBL 2415 or 2416 diaphragm and give it a listen. Aluminum diaphragms with a plastic surround like the 3" JBL diaphragms use sound different! The Radian 1225 Won't work right on a JBL 2417 driver though because of the aforementioned extra space between the diaphragm dome and the 2417 phase plug.


Do You have exact measures? Weights and thicknesses?

joe
11-20-2013, 04:27 PM
not sure about those particular drivers but the 2430 differed from the 2431 only in the wire gauge that was used in the voice coil . the voice coil winding depth remained the same, the membranes were both the same thickness ,etc and voice coil wires are so small on these things to begin with that you cant see the differences . you need a ball point or needle point micrometer and be very gentle in using the friction thimble . A fine scale may also be useful ,if there is a difference it could be less than 1 gram , as you know,in the case of of 2431 jbl used a smaller wire to drop the weight from 2 grams to 1.6 grams .

http://www.audioheritage.org/vbulletin/showthread.php?9745-Quick-amp-Dirty-4430-Inspired-Two-Ways-Part-I&p=54746#post54746

Rudy Kleimann
11-22-2013, 09:45 AM
Do You have exact measures? Weights and thicknesses?

No. But suffice it to say that I can speak with certaintly that the diaphragms and drivers are different and NOT interchangeable.

Maybe one day -IF I ever blow up a 2417 diaphragm, I'll cut and measure it against one of my blown 2416 dias. laying around.
While I'm at it, I'll measure the heights and groove depth (if any) on the magnet and phase plug on each driver and post that.
One day...

You can spot the differences in the diaphragms: The 2417 diaphragm has tinier diamond pattern in the surround and a shiny, smooth, 2-piece plastic cap.

Rudy Kleimann
11-22-2013, 09:49 AM
not sure about those particular drivers but the 2430 differed from the 2431 only in the wire gauge that was used in the voice coil . the voice coil winding depth remained the same, the membranes were both the same thickness ,etc and voice coil wires are so small on these things to begin with that you cant see the differences . you need a ball point or needle point micrometer and be very gentle in using the friction thimble . A fine scale may also be useful ,if there is a difference it could be less than 1 gram , as you know,in the case of of 2431 jbl used a smaller wire to drop the weight from 2 grams to 1.6 grams .

http://www.audioheritage.org/vbulletin/showthread.php?9745-Quick-amp-Dirty-4430-Inspired-Two-Ways-Part-I&p=54746#post54746

True. I have a new diaphragm but I'm unsure if it's a 2430 or 2431 diaphragm and need to figure that out.
One day, 1audiohack and I will get that info nailed down... we own a few of each drivers between us and he has experience and tools for the job.
One day... ;)