JBL 2405 low output

[David Ketley]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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.

[David Ketley]

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]

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]

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