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David Ketley
03-23-2016, 01:36 PM
I'm running a 4 way system and have been trying to set up the speakers but find one 2405 is giving 10db more output than the other 89 to 101.

Yes I've swapped leads changed sides even checked they are both H.

Does this mean one is blown or has gone high resistance?

Welcome any ideas.

Dave

JeffW
03-23-2016, 03:26 PM
You might check the DC resistance just to see. And I think 10dB is about the difference between the JBL and aftermarket diaphragms - do you know the history of the drivers/diaphragms?

David Ketley
03-23-2016, 05:06 PM
You might check the DC resistance just to see. And I think 10dB is about the difference between the JBL and aftermarket diaphragms - do you know the history of the drivers/diaphragms?

I brought them from the US as an orthogonal mint pair last year.

I will check the DC resistance.

I was trying them out on a vintage Yamaha M 60 amplifier in class A just purchased and updated.

It seemed a bit hit and miss on that channel, I'm wondering if a possible fault on the amp has caused the damage?

Challenger604
03-23-2016, 06:57 PM
I brought them from the US as an orthogonal mint pair last year.

I will check the DC resistance.

I was trying them out on a vintage Yamaha M 60 amplifier in class A just purchased and updated.

It seemed a bit hit and miss on that channel, I'm wondering if a possible fault on the amp has caused the damage?

Could be! Swap the left and right, check if it does do the same. Wiring, crossover, connection etc...

I found out on my system that I had to Re-calibrate my EQ. (Sabine).
what 4 ways do have?

Allanvh5150
03-23-2016, 09:37 PM
It could pay to open them up. I have seen many rings with shattered diaphragms and perfect coils. They tend not to make much sound in this state though.

Allan.

David Ketley
03-24-2016, 03:08 AM
Could be! Swap the left and right, check if it does do the same. Wiring, crossover, connection etc...

I found out on my system that I had to Re-calibrate my EQ. (Sabine).
what 4 ways do have?

JBL 2245
JBL 2123
JBL 2450
JBL 2405

Changed everything including the amplifier

Lee in Montreal
03-24-2016, 05:33 AM
I'm running a 4 way system and have been trying to set up the speakers but find one 2405 is giving 10db more output than the other 89 to 101.

Yes I've swapped leads changed sides even checked they are both H.

Does this mean one is blown or has gone high resistance?

Welcome any ideas.

Dave

I bought a set of "mint" 2402 bullets a few years ago. "Mint" was only the seller's description. I tested them and one had a much lower output than the other. One tweeter had a JBL diaphragm, the other was aftermarket. hence the difference in output. Seller reluctantly sent me a used JBL diaphragm...

Mannermusic
03-24-2016, 06:44 AM
I bought a set of "mint" 2402 bullets a few years ago. "Mint" was only the seller's description. I tested them and one had a much lower output than the other. One tweeter had a JBL diaphragm, the other was aftermarket. hence the difference in output. Seller reluctantly sent me a used JBL diaphragm...

Ditto, for what it's worth (including the "mint"). Also measured response and found it falling off seriously above 9-10K. Disaster. Forget the aftermarket diaphragms. I suppose we should all snap up a pair of genuine JBL while they are still available. MM

David Ketley
03-24-2016, 07:00 AM
I bought a set of "mint" 2402 bullets a few years ago. "Mint" was only the seller's description. I tested them and one had a much lower output than the other. One tweeter had a JBL diaphragm, the other was aftermarket. hence the difference in output. Seller reluctantly sent me a used JBL diaphragm...

Visually what is the difference in the diaphragms?

Lee in Montreal
03-24-2016, 07:28 AM
Visually what is the difference in the diaphragms?

There is ample documentation on this forum. With pictures. In your case, simply start by taking the tweeters apart and see if the diaphragms are the same.

David Ketley
03-24-2016, 01:30 PM
There is ample documentation on this forum. With pictures. In your case, simply start by taking the tweeters apart and see if the diaphragms are the same.

A visual inspection shows the diaphragm is certainly damaged it has a small crinkle at the edge.

It has the small black dot denoting genuine JBL?

The worry is why have I damaged it?

I will have to get the amplifier checked out. There was a bit of crackling but I thought that was a loose speaker connection.

I run them via a capacitor direct from the amplifier.

I can buy one here in the UK. Mine are marked 8 ohms but are all the genuine JBL 2405 diaphragms the same?

JeffW
03-24-2016, 01:59 PM
A visual inspection shows the diaphragm is certainly damaged it has a small crinkle at the edge.

It has the small black dot denoting genuine JBL?

The worry is why have I damaged it?

It's very easy to damage them both in the installation and disassembly stage - if the phase plug is allowed to rotate even a bit, the diaphragm can be damaged.




I can buy one here in the UK. Mine are marked 8 ohms but are all the genuine JBL 2405 diaphragms the same?

D16R2405 is the model number, they are all the same. If the diaphragm is marked 8 ohms, it's not JBL.

Here's a pic I took of one a while back, the other side will have the black dot near the - lead.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=47603&stc=1&d=1284692567

David Ketley
03-24-2016, 04:39 PM
Thats extremely helpful but that is that the underside?

I am running mine with just a 2.2 Ufd capacitor maybe I'm not getting my calculations right?

JeffW
03-24-2016, 06:14 PM
Thats extremely helpful but that is that the underside?

I am running mine with just a 2.2 Ufd capacitor maybe I'm not getting my calculations right?

That's the side you see if you just pull the front off and don't remove the phase plug. There's nothing on the other side that you can see without taking it all the way apart. And then it's just a dot, all the markings that matter are on this side.

Can you post pics of what you have?

David Ketley
03-25-2016, 12:20 PM
704927049370494


These don't look anything like the quality of the picture Lea sent.

I brought these from the US from a reputable dealer?

Look forward to your comments.

Dave

grumpy
03-25-2016, 12:23 PM
That bottom one looks ready for retirement... Both appear to be from JBL.

David Ketley
03-25-2016, 12:40 PM
That bottom one looks ready for retirement... Both appear to be from JBL.

Thanks for that. I'm tempted to just buy another pair as the cost is not more than two diaphragms.
Dave

Challenger604
03-25-2016, 01:42 PM
704927049370494


These don't look anything like the quality of the picture Lea sent.

I brought these from the US from a reputable dealer?

Look forward to your comments.

Dave


Oh yeah!! I remember! The funny looking spaceships that my wife wouldn't want in the house!
Please! Don't be offended! You know how women can be!
I thought you build it!
C

Yeah! Your diaphs are busted!

JeffW
03-25-2016, 01:42 PM
Thanks for that. I'm tempted to just buy another pair as the cost is not more than two diaphragms.
Dave

Yeah, but then you risk getting two that are in the same shape as the ones you have now.

David Ketley
03-25-2016, 02:37 PM
Oh yeah!! I remember! The funny looking spaceships that my wife wouldn't want in the house!
Please! Don't be offended! You know how women can be!
I thought you build it!
C


Yeah! Your diaphs are busted!

I suppose it very much depends on your priorities these are in a dedicated listening room and are still very much work in progress, sorting out the 2405s is my priority.
My wife likes them.

BMWCCA
03-25-2016, 03:49 PM
My wife likes them.
Give your wife a big hug from all of us! :applaud:

Challenger604
03-25-2016, 05:04 PM
Give your wife a big hug from all of us! :applaud:

LOL!

David Ketley
03-26-2016, 02:44 AM
I have a question that replacing the diaphragms of the JBL 2405 poses how about going up to Beryllium?

I can purchase Focal TB871 Beryllium inverted dome tweeter for a little over 400 but what's the alternative with JBL?

Remember I'm running JBL 2450 in a E-JMLC horn crossing at about 8000 hz.

mech986
03-27-2016, 02:44 AM
You might just consider getting 2 new OEM diaphragms (if available in the UK) and have them installed by a JBL authorized service agent, again if one exist near you.

Otherwise, shipping to and from the US for service may be too expensive.

Challenger604
03-27-2016, 02:49 AM
If you know what you are doing, you could do it yourself. You would save a lot!
It's not too complicated...
C

David Ketley
05-17-2016, 07:00 AM
You might just consider getting 2 new OEM diaphragms (if available in the UK) and have them installed by a JBL authorized service agent, again if one exist near you.

Otherwise, shipping to and from the US for service may be too expensive.

Just thought I would update members on my 2505 problem. I ended up purchasing another pair but when I connected these up the output was 10db more than the good old one!

There is also a marked difference in the quality of the sound they produce.

I purchased my originals from what I thought was a very reliable source in the US paying top dollar for what I thought were genuine JBL.

I think the lesson here is don't trust ANY dealer, the difference in the value of the genuine unit to the one with non JBL diaphragms is to great.

The dealer now tells me that as I purchased them in 2014 he is not willing to compensate me.

Beware!

JeffW
05-17-2016, 08:27 AM
I think a prudent approach would be to assume that any used ring radiator/compression driver you buy will need new diaphragms, and then buy new (correct) diaphragms for them. Post #19 was my take back then ;)

$200/ea is indeed an obscene amount to pay for the correct diaphragms, but that's what it'll cost to get them running like they are supposed to. Those ring radiator tweeters are a real challenge. A used pair without diaphragms is basically worthless, as just a pair of diaphragms is already more than most people want to pay for a pristine set of tweeters. The aftermarket diaphragms don't seem to be worth postage - those are usually the guys who show up here, wondering what's wrong with their "JBL" tweeters.

So yeah, hard lesson learned the hard way. Sell a pair "as is", take that money and put it towards a diaphragm. Save up the money for the other diaphragm, and you're set!