JBL 2123 cone stuck

[David Ketley]

After much looking I found some as new JBL 2123s still in there original boxes. But on installing them it became apparent one cone was not moving.

After seeking advice I decided to put enough pressure on the cone to release it but now it seems to rub intermittently.

Is this a problem likely to resolve itself with time as the speaker is used.

There is a lesson here for all those with a store of units, turn them over frequently.

Dave

[speakerdave]

Just for clarification, were the boxes still factory sealed?

[Mannermusic]

Like speakerdave sez - truly pristine? Anyway, I've come across two or three of these and each time the rear vent foam filter has disintegrated with age and worked its' way into the voice coil. Can often be salvaged. Dentist tools! Doubt these smaller speaker spiders/surrounds would "sag" with age. Too stiff. Also, could remove the dust cap and look for excessive adhesive having drained into the bore/voice coil during original assembly. Let us know what you find! MM

[David Ketley]

No the boxes were not sealed, North Reading Engineering sold them to me.

The rubbing is only slight so Ive put them over a radiator face up, yes its still that cold here in the UK, and have been pushing them in and out a few times. They store face down I guess so will try a test later and see if there is any change.

You would not believe the problems Ive had getting a good clean pair, just my luck.

dave

[martin2395]

Like speakerdave sez - truly pristine? Anyway, I've come across two or three of these and each time the rear vent foam filter has disintegrated with age and worked its' way into the voice coil. Can often be salvaged. Dentist tools! Doubt these smaller speaker spiders/surrounds would "sag" with age. Too stiff. Also, could remove the dust cap and look for excessive adhesive having drained into the bore/voice coil during original assembly. Let us know what you find! MM


That's a major problem with JBL units, I had a pair of 2213h with the same problem - cone stuck firm with foam that turned into pieces of sticky goo and fell just right between the VC and the magnet assembly.

I had them turned upside down and gave them a good go at 25-30Hz on my Crown K2 for a few hours. In the end they spit all the pieces of foam.
They land on the dustcap so you will hear a rattling noise for sure. You have to remove the label at the back to get the particles out, though.

[David Ketley]

That sounds as though its the problem. The voice coil is not rubbing and already although I've only run it at crossover frequency and manually given it a good pummelling it sounds better. There is hope this unit yet.
Hard work this HiFi thing, two expensive amps have also gone faulty.

Thanks

Dave

[martin2395]

It's a part of our hobby. I've had a Krell KSA50 that would randomly cut off on one channel and never found a solution.

I've paid like €300 to replace some caps and redo the solder joints and get it back to 100% spec and while it worked great at the shop, it still had the drop out issue at my place.

In the meantime I had different preamps, poweramps, cables, crossovers - none fixed the issue.

I sold it to a friend of mine and afterwards I've also spoken to the guy who serviced the amp and he mentioned that he didn't clean the loudspeaker relays as he didn't see a reason to do so....:banghead:

[Mannermusic]

It's a part of our hobby. I've had a Krell KSA50 that would randomly cut off on one channel and never found a solution.

I've paid like €300 to replace some caps and redo the solder joints and get it back to 100% spec and while it worked great at the shop, it still had the drop out issue at my place.

In the meantime I had different preamps, poweramps, cables, crossovers - none fixed the issue.

I sold it to a friend of mine and afterwards I've also spoken to the guy who serviced the amp and he mentioned that he didn't clean the loudspeaker relays as he didn't see a reason to do so....:banghead:

Yep. And, the more complex the system the worse it gets. I ran a tri-amp for 25 years and it gradually became impossible to deal with. Stuff was intermittent, wouldn't act up in the shop, couldn't find parts, etc. Started over. As you say, part of the hobby. Mike

[David Ketley]

That's a major problem with JBL units, I had a pair of 2213h with the same problem - cone stuck firm with foam that turned into pieces of sticky goo and fell just right between the VC and the magnet assembly.

I had them turned upside down and gave them a good go at 25-30Hz on my Crown K2 for a few hours. In the end they spit all the pieces of foam.
They land on the dustcap so you will hear a rattling noise for sure. You have to remove the label at the back to get the particles out, though.

That seems exactly the problem its actually sticky I can feel it at the back when pushing the coil in its adhering. I will consult with John at North Reading Engineering before doing anything, Im absolutely sure he had no intention of supplying a speaker in this condition.

Dave

[Mannermusic]

That seems exactly the problem its actually sticky I can feel it at the back when pushing the coil in its adhering. I will consult with John at North Reading Engineering before doing anything, Im absolutely sure he had no intention of supplying a speaker in this condition.

Dave

And best check the other speaker while you're at it. Most likely in similar condition. Get 'em both.

[David Ketley]

The other speaker is installed and is fine.

Dave

[martin2395]

If you're sure that one of them is sticky, then you can be 100% sure that the other one is in the same condition and will develop the same problem sooner or later (unless that one has been reconed later)

Maybe he can remove the dustcaps and vacuum the debris out.

[David Ketley]

Well the speaker is reinstalled after my cooking it on a radiator and giving it a good pummelling. I can see the foam from the back its intact and seems in good condition so I'm just going to listen to music and enjoy.

Now to find some good Class A amps at the right price,the weather is appalling here in the UK its like winter, the extra heat will be welcome.

[Earl K]

Well the speaker is reinstalled after my cooking it on a radiator and giving it a good pummelling. I can see the foam from the back its intact and seems in good condition so I'm just going to listen to music and enjoy.

Now to find some good Class A amps at the right price,the weather is appalling here in the UK its like winter, the extra heat will be welcome.

Instinctively, "par-boiling your woofers" & then giving them a "severe thrashing", hardly seems the correct approach . :blink:

Care to explain how this worked for you ?

:)

[David Ketley]

Keeping in mind radiators run at about 50C, 122 F the glue or whatever it was must have moved with the heat, they were face up on the basis they are always stored face down. I just pushed them in and out to get the surround flexing again and acting as a proper suspension.
The foam that was cited as causing the problem seemed in good condition.

[Earl K]

Keeping in mind radiators run at about 50C, 122 F the glue or whatever it was must have moved with the heat, they were face up on the basis they are always stored face down. I just pushed them in and out to get the surround flexing again and acting as a proper suspension.
The foam that was cited as causing the problem seemed in good condition.

Okay, Thanks for that !

:)