708G-1 Spider/Cone Separation

[mortron]

Well the title is pretty self explanatory... I have some L5's with their lower woofers in poor shape - the cones and spiders have come apart. It appears its just at the lamination point... are these at all repairable? The coils are probably not properly centered anymore either. I know factory cone and driver replacements are NLA. Pretty gutted, as it was not noticed when purchasing the speakers. Is this a common issue? Any help is appreciated. Thanks in advance.

[Joseph Smith Jr]

Well the title is pretty self explanatory... I have some L5's with their lower woofers in poor shape - the cones and spiders have come apart. It appears its just at the lamination point... are these at all repairable? The coils are probably not properly centered anymore either. I know factory cone and driver replacements are NLA. Pretty gutted, as it was not noticed when purchasing the speakers. Is this a common issue? Any help is appreciated. Thanks in advance.
The surrounds having separation problems after time and poor adhesives are fairly common issues with this "L" series of systems, as in a frequently documented issue with these woofers especially

I would urge you to consult a qualified JBL repair person that really knows their stuff, maybe they could help with a repair - buying a pair of used woofers would just be asking for more of the same in the form of a ticking time bomb

As for the L5, I don't think there ever was a re-cone kit for that driver or for the 704G mid, it was a replace the driver proposition, in fact the only serviceable driver in the L5 was the 035TiA with the D8R035TiA diaphragm kit but I may be mistaken

The only woofer from this series that was serviceable was the LE120H-1 used in the L7

Sorry

Joe

[mortron]

Spider... surrounds are fine. Maybe the part it joins is called the voice coil former, not cone? I'll try to post pics.

I've tried to contact a few folks and am waiting to see if they can help. Hope so. I've seen aftermarket recone kits but would rather not. I am curious if I should check the other woofers. Thanks for your reply.

Edit: added a photo.

I also think another few folk had similar issues in past... wish I had read those warnings beforehand.

[ivica]

Well the title is pretty self explanatory... I have some L5's with their lower woofers in poor shape - the cones and spiders have come apart. It appears its just at the lamination point... are these at all repairable? The coils are probably not properly centered anymore either. I know factory cone and driver replacements are NLA. Pretty gutted, as it was not noticed when purchasing the speakers. Is this a common issue? Any help is appreciated. Thanks in advance.

Hi morton,

Owing to the
http://reconingspeakers.com/product/jbl-708g-8-aftermarket-recone-kit/
price, I think You can try to use it, or only its voice-coil, but careful cone removal would be a must.
I think that "two-components epoxy glue" would have to be used to glue voice coil+cone+spider.

regards
ivica

[Joseph Smith Jr]

Spider... surrounds are fine. Maybe the part it joins is called the voice coil former, not cone? I'll try to post pics.

I've tried to contact a few folks and am waiting to see if they can help. Hope so. I've seen aftermarket recone kits but would rather not. I am curious if I should check the other woofers. Thanks for your reply.

Edit: added a photo.

I also think another few folk had similar issues in past... wish I had read those warnings beforehand.
This is what I am trying to tell you
There is a materials problem and a there never was a repair option other than driver replacement problem
And now, JBL no longer offers this driver new for sale
That is why I avoid this "L" series like the plague

Hope you get it resolved, you might be better off parting out what's left that's any good out and buying another serviceable model

I realize these are good sounding speakers, but the cons just seem to outweigh the pros

No fun owning a system that's a pain to service if at all no matter how good they may sound, unless it has something else really positive going for it like uniqueness or collectibility

Joe

[Joseph Smith Jr]

Hi morton,

Owing to the
http://reconingspeakers.com/product/jbl-708g-8-aftermarket-recone-kit/
price, I think You can try to use it, or only its voice-coil, but careful cone removal would be a must.
I think that "two-components epoxy glue" would have to be used to glue voice coil+cone+spider.

regards
ivica
That kit is only a "close" fit and requires setting VC depth etc
Not worth the effort or the price unless the OP can do the work himself

Joe

[Joseph Smith Jr]

I also think another few folk had similar issues in past... wish I had read those warnings beforehand.
I think you are correct

The surrounds having separation problems after time and poor adhesives are fairly common issues with this "L" series of systems, as in a frequently documented issue with these woofers especially

I'd get rid of them unless you have a lot tied up in them
I know it's easy for me to say this but it's not as if the issues are going to stop here and at the end of the day these models will never bring any sort of big money

Cut your losses mate and eliminate a potential source of lingering worry from your long term enjoyment

Joe

[mortron]

Guess I should have asked you if these were worth buying eh?

[Joseph Smith Jr]

Guess I should have asked you if these were worth buying eh?
I think they are good sounding speakers and they certainly enjoy a substantial following but obviously they weren't built with the same long game way of thinking that some of the earlier product enjoyed.

Worth buying? Depends on what you have to pay and what you expect out of a system over the long haul if you're the sort who just wants to find something they like and just stick with it. They're right on the cusp of what's considered vintage, or the old way of thinking and current, so service would be inevitable for anything this old but unfortunately JBL didn't choose to make that part of things a very viable option, or at least not continue product support for loyal owners of the line.

That series is like a crossroads product as for corporate philosophy and I think that that is too bad.

Joe

[1audiohack]

I think you can fix that.

I would carefuly cut off the dust cap and either use a factory type shim sleeve or coil a piece of paper in the voice coil gap that evenly takes up enough of the space between the former and the pole piece so not only does the coil stay centered but it will stay where you put it via friction.

Get the spider attached to the former / cone junction in several spots with a near instant adhesive. Then with an epoxy that is thin enough to wet the material but thick enough to stay where you put it, apply a bead around the original glue line.

Glue on a new dust cap and down the road you go.

You have nothing to lose at this point.

Barry.

[mortron]

Thanks for the advice. I hope a pro can do it as they will know more on the fly and be able to do more than me. I will get an estimate and see.

[Joseph Smith Jr]

Thanks for the advice. I hope a pro can do it as they will know more on the fly and be able to do more than me. I will get an estimate and see.
You are wise to have a professional with experience do this level of repair
It definitely can be done and done perfectly by the right person if you can find them
I know of two but they are both in the States
If it comes to that PM me and I will give you contact information for the man I feel is the best
Hopefully you can find someone there as the costs of post will kill ya
Best of luck

Joe

[Joseph Smith Jr]

You have nothing to lose at this point.

Barry.
Yeah he does have something to lose if he plans on trying to keep the speakers, more money, time and a non-repairable repairable driver if in the right hands that they don't make anymore
Botch things up and then he's scrounging the used market
Better to have someone repair the woofer that knows what they are doing and has the correct adhesives

Joe

[1audiohack]

I think you are correct


I'd get rid of them unless you have a lot tied up in them
I know it's easy for me to say this but it's not as if the issues are going to stop here and at the end of the day these models will never bring any sort of big money

Cut your losses mate and eliminate a potential source of lingering worry from your long term enjoyment

Joe

Oh wait! Maybe you do have something to lose!

Yeah OK, whatever.

[Joseph Smith Jr]

Oh wait! Maybe you do have something to lose!

Yeah OK, whatever.
Not a contradiction
The OP said repair people were hard to find where he lives so I figure he'll have an easier go of selling them, if that's what he decides to do, with all the drivers still reparable, not lathered up with a do it yourself effort
The new owner, if it comes to that, might be more amenable to having a repair done and that'll be easier to accomplish with a clean driver albeit a broken one
I'm just taking into consideration both scenarios, selling or repairing, and the best outcome for either, that's all I am suggesting
No need to make an unhappy situation worse with an experiment

Joe

[Chris Brown]

Hey "Joseph Smith Jr", you might look into this neat little feature called the edit button. That's the reason why you don't see others posting back to back in the same thread several times in a row within the span of a few minutes.



I would urge you to consult a qualified JBL repair person that really knows their stuff, maybe they could help with a repair

This site has more collective JBL knowledge than anywhere else on the planet, so I'd say he's already come to the correct place.



buying a pair of used woofers would just be asking for more of the same in the form of a ticking time bomb

Perhaps you can elaborate on what exactly about this series you consider to be a "ticking time bomb" . There are many drivers from over the years which either never had a re-cone kit available or they are no longer available, and many functional fixes have been brainstormed. Recall, JBL doesn't even consider a re-foam to be an acceptable repair. Officially it's re-cone or nothing. It's the community that came through in making re-foaming viable, and I wouldn't be surprised if solutions can be found for other issues also - to the extent that those issues even exist.



This is what I am trying to tell you
There is a materials problem and a there never was a repair option other than driver replacement problem

You are again referring to lack of a recone kit? Would this not apply just the same to all other speakers where recone kits are no longer available for any reason? Who is to say that there isn't a functional solution to the OP's problem?



That is why I avoid this "L" series like the plague

I realize these are good sounding speakers, but the cons just seem to outweigh the pros

No fun owning a system that's a pain to service if at all no matter how good they may sound, unless it has something else really positive going for it like uniqueness or collectibility

Yeah you've made your dislike for the L series very clear in this thread, about a dozen times. I just want to make sure that the OP knows that whatever experience you aparently had which generated so much dislike for these speakers, there are also many of us on here who still love these speakers, and have not had any insurmountable issues with them.



Not worth the effort or the price unless the OP can do the work himself

Doesn't that apply to most speaker repairs? Who is to say that the OP can't do the work himself?



I'd get rid of them unless you have a lot tied up in them
I know it's easy for me to say this but it's not as if the issues are going to stop here and at the end of the day these models will never bring any sort of big money

Cut your losses mate and eliminate a potential source of lingering worry from your long term enjoyment

The value of these models has gone up consistently especially with the wealth of knowledge and discussion to be had on sites such as this. They have largely been rediscovered in the last 10 years, creating many very happy users who have had few if any issues with them. That isn't to say that problems can't or won't happen, but you seem to be trying to mold the discussion into a narrative that suggests these problems are inevitable and not worth the risk. You could probably extend that logic to any vintage speaker, but most of us are doing just fine even with speakers that are double or more the age of the 90's L series.

While I'm sure that your hatred of these speakers does have some real-world basis, the positive experiences that so many of us have had with these speakers should also be taken into account.



Yeah he does have something to lose if he plans on trying to keep the speakers, more money, time and a non-repairable repairable driver if in the right hands that they don't make anymore
Botch things up and then he's scrounging the used market
Better to have someone repair the woofer that knows what they are doing and has the correct adhesives

No need to make an unhappy situation worse with an experiment

The idea that it's always better to have a "pro" do it, is a blanket statement that you can probably apply to any repair. Certainly no repair should be attempted unless using the "correct" adhesives, etc, but that is hardly unobtainable information in this era of the internet. God forbid anyone actually attempt a repair, the might "botch things up"!

OP, I wish we had more information about what happened to that driver before you bought the speakers. My guess would be that they were simply pushed too hard, probably to the point of repeated over-excursion, where the only thing stopping the cone movement is either the spider reaching it's limit (which would explain the detachment) or the voice coil physically hitting part of the magnet assembly. The L5 is an amazing speaker, but in my opinion the 8" woofer is undersized. IIRC even the designer himself (who posted on these forums) wished it had a 10". The 8" driver isn't bad, but it will hit it's limits a lot quicker than other JBL speakers with a 10" or 12". Having that happen occasionally still should not cause problems, but if we imagine something like a party where the music is cranked and everyone is walking around half-drunk, it's not difficult to imagine the woofer sitting there destroying itself over the course of the night. Here is an example of what you can expect from a 708G-1 very near it's maximum bass output: https://www.youtube.com/watch?v=1ZR12g1WJgw This level of output would be almost trivial for a 12". Again that isn't to say that the 8" is bad or even deficient, but the L5 probably benefits more from a sub than most JBL speakers. An L5 with a subwoofer, where the 708G-1 is no longer burdened with the lowest frequencies, would eliminate the over-excursion risk, and would likely best most other JBLs.

[Joseph Smith Jr]

OP, I wish we had more information about what happened to that driver before you bought the speakers.
Are you done?

How is knowing what happened before he bought the speakers going to change his current situation?

We already know what's happened, his 8"s are coming apart like they all do. Ever wonder why you rarely see them on ePay so much anymore? Used to be a pair being parted out almost daily

The 708G-1, that two of this "L" series uses, suffers a WELL DOCUMENTED MATERIALS PROBLEM and that's just an objective fact, don't know why you're rambling on at me about it

MATERIALS PROBLEM - That means the glue and cone material as well as the surround and VC former all have a bad habit of coming apart with time and nothing to do with the availability of a re-cone kit, then or now

I am aware of the vast amount talent available here, that's why I suggested he use it as he himself seemed (or at least it sounded that way to me) reluctant to attempt effecting any repairs himself - I just don't do public endorsements, exception being parts vendors. Reasons should be obvious to a smart guy like you

If he likes these speakers enough to want them PROPERLY repaired and if he is not an experienced repair person or fairly advanced hobbyist in this field (I don't know, maybe he is, do you know something I don't?) then my advice is the correct advice for a repair this involved, period, because the repair he needs is a high skill level proposition if it's to be pulled off successfully and reliably

Removing and re-using parts successfully takes a little more expertise than the monkey see monkey do of gluing on some new foam surrounds

I don't hate this "L" series speakers and never said I did, and I don't much appreciate your misrepresentation of the truth of what I actually did say

I did say that I avoid them for this very reason
I'm getting older and am tired of every vintage acquisition presenting as a project

Joe

[mortron]

Thanks Chris Brown.

My cones weren't moving that much... makes me wonder what backside of his cones look like. But mine did move a good deal.

I'm super gutted. I am not sure when it happened and accept responsibility for them but was not pushing them near as hard as that video shows nor was I listening to EDM. Listened to some acoustic music and then some Stone Temple Pilots and saw the cones moving a heck of a lot and when close up could hear the friction of spider (didn't know at the time). Shut er down and pulled the woofer and saw what is seen in the photo. I don't think the issue was known to seller, or hadn't become an issue at the time.

Source was CD using a Crown XLS 1500 amp, so no subsonic vinyl rumble. Looks like dried out adhesive gave way on he seam.

[Chris Brown]

How is knowing what happened before he bought the speakers going to change his current situation?

It won't, but it would be useful to know of real-world situations that can result in this kind of damage. I don't personally subscribe to your "ticking time bomb" theory, and find it much more likely that abuse is the cause.

[Joseph Smith Jr]

It won't, but it would be useful to know of real-world situations that can result in this kind of damage. I don't personally subscribe to your "ticking time bomb" theory, and find it much more likely that abuse is the cause.
Then you need to research the 708G-1 and think before you pop off

Joe

[mortron]

It won't, but it would be useful to know of real-world situations that can result in this kind of damage. I don't personally subscribe to your "ticking time bomb" theory, and find it much more likely that abuse is the cause.

I'm normally quite conservative with my speakers and such, and tend to get nervous easily. I can say for certain that this same setup has been used on numerous other speakers driven to much higher levels, so presume it was not abuse. Unless there is something I am missing about these speakers.

What one could consider is that if the speakers sat long enough they could have just dried out and given with minimal use after laying dormant. I wouldn't rule anything out.

I'll be honest that I did not demo the speakers when I bought them as I was pretty confident in their condition and the seller. He's a nice guy and at his age had little to gain from deceiving me.

As I said, with some acoustic music it wasnt noticeable. The bass seemed nice and full. I played a song off the first STP album I demo often, and the woofers were flailing. Stopped it and put another half song on and noticed same movement and then looked deeper leading to the photo posted earlier.

[BMWCCA]

Wow! The Mods pared down this thread and still left most of Joseph Smith Jr's vitriol unchallenged. Yet every one of my replies is now gone.

In case anyone discovers this thread in the future, let me say again: I have enough L7, L5, and L3s to have ten of this particular driver with NONE of them exhibiting any failures, particularly nothing like what's mentioned here. I also suggested that the L3 can normally be found around $150 and they make excellent donors for the 708G-1 as well as the even-more-fragile 035Ti tweeter. Just check the surrounds for abuse, though they can be repaired with conventional foam replacements.

I also suggested that the designer and engineer for this series, Chris Hagen who is a member here, supplied a great snapshot of the history of the '90s L-series and spoke about the quality of the drivers and how the only economy decision was to go a little cheap on the cabinets and their finish. Not the drivers.

Just trying to set the record straight. Again.

[Mr. Widget]

Wow! The Mods pared down this thread and still left most of Joseph Smith Jr's vitriol unchallenged. Yet every one of my replies is now gone. Not intentionally. I couldn't be bothered to read all of the BS. I simply deleted the most obvious issues that I noticed with a very casual review.

If there are questions that still need to be answered, I hope people will step up. I also hope "Carlos Danger" or what ever name "Joe" thinks he should use next, simply chooses to stay away. While he occasionally offered help and good advice, his disruptive behavior can't be allowed to continue.


Widget

[mortron]

Thanks Widget.

As for the subject at hand, I've spoken to a somewhat local pro who I will take my woofers to for a proper assessment. He did the recone on 8 of an acquaintances LE-128's and came highly recommended.