2445 diaphragm question

[jerv]

I bought a pair of 2445J on eBay for my 2360 horns. They look ok, but I'm unsure about the diaphragms. From the attached picture: can any of you guys tell me if this is JBL original?

And if I decide to replace them: what is the "preferred" JBL replacement? I have searched, but am still bewildered. The aquaplased 2450? Ribbed or non-ribbed?

I use them for hi-fi, in my home listening room - crossed at about 600 Hz (to 2204H's) and 8 kHz (to 2405's).

[robertbartsch]

I have a set of these in 8 ohm trim that I also use for Hi-Fi. The frams look like the original factory ones to me. Why do you suspect they might need to be replaced?

...others here will provide their view on the frams originality.

Do you have an Ohm metter; what do they read?

I use only factory JBL diaphragms for good reason.

[jerv]

My two units measures 7,8 and 7,4 ohms. The dias look fine to me - but if they are non-JBL, I would replace them anyway.

From reading around on the forum, I have understood thay many find the 2445 titanium diaphragms to sound somewhat hard. (For example: see post http://www.audioheritage.org/vbulletin/showpost.php?p=92261&postcount=5 ).
My own listening seem to confirm this. If the newer aquaplased diaphragms sound better, I would be inclined to try those. But I'm unsure about which diaphragm to choose (and bewildered by the many alternatives): 2450 ribbed or non-ribbed, 2452-SL, etc, etc.

[John]

Sure look like the real deal to me!;)

[Jakob]

In the photo it looks to be some red paint on the positive lead on the diaphragm. If my memory serves me correct, this is how JBL marks their 16-Ohm dias as the 8-Ohms get green marks. How ever, I'm not sure if other diaphragm-manufacturers do this as well. It looks genuine to me.

I've tried both 2445, 2450 and 2450sl dias in my 2450's. I couldn't tell any difference between 2445 and the ribbed 2450. The smooth 2450sl sound less harsh in my opinion. But that's my very own subjective thought. I was rather happy with the 2445's and 2450's as well.

[robertbartsch]

These drivers have some very high sensativity so your observation that they sound a tad harsh may be related to them over-powering the rest of your system (e.g. the woofer(s)).

What other drivers are you using for the LF sound and do you have an attinuator to turn down the 2445?

If you still find harshness, I suppose you could either add a UHF tweeter such as the 077/2405 or try the aqua frams.

New diaphragms for these "big" guys are not cheap, however.

[jerv]

Thanks for your answers all.

I use my 2445's in 2360 horns. I have 2405 for UHF, 2204 for lower mid and 2245 for bass. Crossover frequencies are 80 Hz, 600 Hz and 8 kHz. I use quad-amping (2x250W SS units of own construction), with a combination of passive networks and a dbx DriveRack 260 - eq and delay as required (I have good measuring equipment).

The system is far from ready - still under development and tweaking.

I think I will try the aqua 2450SL diaphragms next. All advice is welcome.

[robertbartsch]

I would think that any perceived harshness from a 2445 would be in the upper frequencies. I think if your running a slot tweeter in this system there would not be noticible improvement in harness by switching to auqu coated frams in the big 2" drivers.

Others may have a different view, however.

[robertbartsch]

I've had many 2-way and 3-way compression horn systems for Hi-Fi over the years. One new system that uses 2225, 2445s, 2402s are the latest. I'm using these with two 2245 subs in separate cabs.

Anyway, for the first few times I listened to them I was not sure I liked the big 2" drivers. My 2445s were E-bay purchases and I installed new JBL 8 ohm frames when the arrived.

However, the more I listen to them, the more I like them.

My advice would be to give them an honest workout over many sessions before you consider any future mods.

Good luck!

[dhs speakers]

yes it is, the center dot type damper is the indicator, also if you look inside the former of the winding area? it might have pencil or pen inspection signatures, and there should be a stamped model/production # and mayba date?

[grumpy]

Useful info, even if nearly a decade late ;)

[sguttag]

Yeah, I noticed the date too! :)

Another clue to genuine JBL (no guarantees as to which years it was used) is that JBL would measure their compression driver phase plug physical height as well as the dome of their diaphragms. Good ones would be in the range of +3 to -3 (though I've seen some out of that range). Ideally, you want to match the numbers to have the ideal spacing between the dome and the plug. What you don't want is a +3 plug with a -3 diaphragm because the clearance would be tight.

The driver's number is typically right under the gasket/boot and is likely that red marker that is peaking through on the original photo. The diaphragm number will be on the v.c. former so you'd need to take the diaphragm out to see it. For the record, I've seen has high as +/- 6. You want to keep the differential to within 3.