LE15 repair/restoration

[budney]

A while back I acquired a pair of 4320 in need of restoration. With it I got 3 15 inch woofers, all a little bit different.

I got 1 LE15A that works, 1 LE15B that measures open, and one empty basket. With it I also got 3 aftermarket Sound Speaker Repair LE15A recone kits.
I'm trying to figure out my best option is here. The LE15B doesn't crunch or scratch, cone moves freely, so I'm wondering if perhaps a wire has come loose, and it could be repaired, as I would like to keep it all JBL OEM stock parts if possible. Then theres the issue of the A vs B, as far as I can tell, the different between the A and B is the foam vs cloth surround. Would it be possible to remove the cloth and replace it with foam, so I will then have another LE15A? Assuming the coil can be repaired of course.

The other option to me is to remove the LE15B cone and replace it with an aftermarket kit, then recone the empty basket also with an aftermarket kit. I want to avoid this, as I know that the aftermarket parts are substandard. But since the genuine JBL LE15A kit is no longer available, I don't see any other option to me. I would then be left with a single original LE15A. I have found elsewhere in the UK a single 2215B that has been reconed with a genuine 2215H kit, so I could potentially have a pair of working original LE15, but its not cheap and I've ran out of money for this project.

I had planned on getting the drivers regaussed if I were reconing them. I'm in the UK so its not easy to get things regaussed, I've found one guy who wants to charge £40 per driver. I found someone else who said they could do it much cheaper but they're still in the process of setting up their machine so I would have to wait on that. I've just opened a music studio and would like to get these monitors up and running in the next month, so I'm unsure on what approach would be best.

The working LE15A looks decent, someone replaced the foam at one point it seems. LE15B also looks good, so it would pain me to scrap what seems to be a good condition LE15 cone. Also the working LE15A is labelled as 8 ohms, but measure more like 16, so not quite sure whats going on there.

attached are some pics
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[budney]

here are the recone kits
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84636

[ompdiburi]

For the open LE15B it could be the lead wires from cone to binding posts, check direct on the cone at coil exit.
If you are lucky is possible to repair, had the same issue years ago on a beyma.
At that point you can decide, you have one working LE15A and one working LE15B, so you need to recone the basket according to your decision.
Good luck!
Giuliano

[Mr. Widget]

I’d put the aftermarket kit in the empty basket and compare the performance with your working LE15A. Ideally you would have both the LE15A and reconed woofers remagnetized so that variable is out of the mix. By comparing the two woofers you can decide how to proceed. I wouldn’t spend heroic efforts on the LE15B. In my opinion they are not as good a driver as the A version.


Widget

[1audiohack]

Mr Widget captured my thoughts exactly.

There is every possibility that a quality aftermarket cone kit could out perform a 40+ year old “proper” cone kit anyway.

Barry.

[budney]

I’d put the aftermarket kit in the empty basket and compare the performance with your working LE15A. Ideally you would have both the LE15A and reconed woofers remagnetized so that variable is out of the mix. By comparing the two woofers you can decide how to proceed. I wouldn’t spend heroic efforts on the LE15B. In my opinion they are not as good a driver as the A version.


I was under the impression that you needed to get things remagged before reconing, some more reading on this site and I see thats not the case, so i'll try the aftermarket kits and compare to the original. It may be that they sound fine, then I could sell the original one for a collectors amount of money...

The LE15B is a bit of a mystery to me, as far as I can see the only difference is the cloth surround. How would that impact its performance?



There is every possibility that a quality aftermarket cone kit could out perform a 40+ year old “proper” cone kit anyway.


I had thought that myself when I got these parts, but then talking to a few old school JBL certified guys, they said the LE15 coil is pretty much impossible to find and wouldn't trust aftermarket parts...but I'm 20 years too late to find a genuine kit now. I'll have to let my ears be the judge!

[Mr. Widget]

The LE15B is a bit of a mystery to me, as far as I can see the only difference is the cloth surround. How would that impact its performance?
The two woofers have substantially different TS parameters and even very different impedances. There are many differences beyond the visually obvious surround type.


Widget

[speakerdave]

. . . . I had thought that myself when I got these parts, but then talking to a few old school JBL certified guys, they said the LE15 coil is pretty much impossible to find and wouldn't trust aftermarket parts...but I'm 20 years too late to find a genuine kit now. I'll have to let my ears be the judge!

I don't know exactly when the real kits were discontinued, but I'm pretty sure it hasn't been twenty years-- more like five. Point being NOS kits do show up once in awhile, and it might be worthwhile keeping an eye to the various markets for such things. At the same time you could be looking for a single LE15A or 2215B.

[Earl K]

The working LE15A looks decent, someone replaced the foam at one point it seems. LE15B also looks good, so it would pain me to scrap what seems to be a good condition LE15 cone. Also the working LE15A is labelled as 8 ohms, but measure more like 16, so not quite sure whats going on there.


What do you mean by the words that I've underlined?

Is that "16" an actual DCR reading from a meter that you trust?

A healthy Le15a will have a DCR measurement in the neighborhood of 8 to 10 ohms.

:)

[budney]

The two woofers have substantially different TS parameters and even very different impedances. There are many differences beyond the visually obvious surround type.


Okay, definitely not worth trying to swap the surround. I just don’t feel right about scrapping what looks to be a good condition cone, but there’s not much else I can do...




What do you mean by the words that I've underlined?

Is that "16" an actual DCR reading from a meter that you trust?

A healthy Le15a will have a DCR measurement in the neighborhood of 8 to 10 ohms.

:)

It worried me, as the cone kits I have are definitely 8 ohms, so if it were 16 then I wouldn’t be able to compare them. I went back and checked again, turns out the terminals are corroded and throwing off the value. Direct on the lead wires I get a solid 9 ohms :)

[ompdiburi]

Okay, definitely not worth trying to swap the surround. I just don’t feel right about scrapping what looks to be a good condition cone, but there’s not much else I can do...



It worried me, as the cone kits I have are definitely 8 ohms, so if it were 16 then I wouldn’t be able to compare them. I went back and checked again, turns out the terminals are corroded and throwing off the value. Direct on the lead wires I get a solid 9 ohms :)

Did you get the 9 ohms on both or only the LE15A?

[budney]

Did you get the 9 ohms on both or only the LE15A?

Only on the LE15A. I currently only have 1 working driver, and that’s around 9 ohms. I had thought about repairing the LE15B but it’s not worth it

[Earl K]

Only on the LE15A. I currently only have 1 working driver, and that’s around 9 ohms. I had thought about repairing the LE15B but it’s not worth it

If the Le15B is repairable then it is also sellable ( mostly to the Japanese from what I've seen over the last 15 years ).

The braided lead-in wires ( from terminals down into the VC leadouts ) do corrode and can break at the solder joint hidden underneath black glue line ( as seen below , down by the dustcap ).

https://thumbs.worthpoint.com/zoom/images3/1/0211/26/pair-jbl-le15b-le-15b-l200-2216_1_3f1aafd9c5792d78b002425bfccbb9d3.jpg

Fixing that is a job for a top-tier pro reconer.

You might also want to simply try selling that le15B into the Asian market ( on a "for Parts" basis ) .

Japan has the type of speaker repair shops that could do this job.

The following pic shows the web-address of one such master repair shop ( which is why I suggest focusing resale efforts into countries where they will do everything to save the original parts of these Legacy drivers.

http://www.audioheritage.org/photopost/data//500/416-8B_10013249151.jpghttp://www.audioheritage.org/photopost/data//500/2235h_x4_10015979762.jpg

http://www.audioheritage.org/photopost/data//500/le15a_OLDvsNEW_edge_100033807491.jpg http://www.audioheritage.org/photopost/data//500/406-8C_10140290541.jpg

What's clear to these eyes is that the master tech ( doing the work in the above pics ) removes the complete cone assembly ( while saving most of the parts ) and then re-assembles /re-centers without disturbing the existing cone/coil/dustcap assembly. That's true art!

<> Earl

PS; If you do get the le15B reconnected the DCR should read somewhere between 4.5 to 6 ohms ( if I remember correctly it's surprisingly low ) .

[budney]

If the Le15B is repairable then it is also sellable ( mostly to the Japanese from what I've seen over the last 15 years ).

The braided lead-in wires ( from terminals down into the VC leadouts ) do corrode and can break at the solder joint hidden underneath black glue line ( as seen below , down by the dustcap ).

Fixing that is a job for a top-tier pro reconer.

You might also want to simply try selling that le15B into the Asian market ( on a "for Parts" basis ) .

Japan has the type of speaker repair shops that could do this job.


Selling it was on my mind, but then I would be left with one original and one aftermarket driver, and I can't see them being close enough to be used as a pair. A different thought I had was to sell the working LE15A, as it would probably bring more money, and just recone the B and basket with the aftermarket cones.

I had thought that it may be possible to extract the B cone assembly as complete as I can, and then try and sell that to the asian market for parts, but I'm not sure how to remove it so it remains mostly intact. As you say its a job for a real pro who has been doing this for years.

[Earl K]

Selling it was on my mind, but then I would be left with one original and one aftermarket driver, and I can't see them being close enough to be used as a pair. A different thought I had was to sell the working LE15A, as it would probably bring more money, and just recone the B and basket with the aftermarket cones.

I had thought that it may be possible to extract the B cone assembly as complete as I can, and then try and sell that to the asian market for parts, but I'm not sure how to remove it so it remains mostly intact. As you say its a job for a real pro who has been doing this for years.

All that seems like a good plan ( but why not recone the empty basket first before doing anything else just to see just how close to the recone sounds to an actual le15a ).

Cone Removal ( complete ):

Are you allowed to purchase ( by EU/UK rules ) MEK ( Methyl Ethyl Ketone ).

It's commonly used by reconers to loosen up hardened/aged glue.

It's highly volatile ( brain damaging even ) and must be used in a well ventilated area ( outdoors with a slight breeze is best ).

I believe the next best might be Acetone.

:)

[budney]

All that seems like a good plan ( but why not recone the empty basket first before doing anything else just to see just how close to the recone sounds to an actual le15a ).


I am in no rush to sell anything, I will make sure I am certain with my final choice before that happens. I still need to refinish the cabs and sort out the crossovers, getting that tar stuff off is going to be a fun job. Once I've finished those jobs then I can start testing different woofer configurations, and hopefully one day get them remagged too.



Cone Removal ( complete ):

Are you allowed to purchase ( by EU/UK rules ) MEK ( Methyl Ethyl Ketone ).

It's commonly used by reconers to loosen up hardened/aged glue.

It's highly volatile ( brain damaging even ) and must be used in a well ventilated area ( outdoors with a slight breeze is best ).

I believe the next best might be Acetone.

:)

Yes I can find MEK here, am I best using it to loosen the glue on the surround and spider? What is the best technique for doing that?

[Earl K]

I am in no rush to sell anything, I will make sure I am certain with my final choice before that happens. I still need to refinish the cabs and sort out the crossovers, getting that tar stuff off is going to be a fun job. Once I've finished those jobs then I can start testing different woofer configurations, and hopefully one day get them remagged too.



Yes I can find MEK here, am I best using it to loosen the glue on the surround and spider? What is the best technique for doing that?

Yes, the spider & surround both need to be released from their glue points.

I imagine ( since I've never lifted a complete cone out ) that a putty knife, Q-tips for targeted application of the solvent is the way to go ( start with the surround since it's furthest away from the other parts of the assembly where you don't want the MEK to loosen the glue bonds ).

You'll need to first remove the cork/foam gasket covering the glued edge of the surround.
- I believe there are some YouTube videos that show the best way to accomplish this task while saving the gasket.

:)

[ompdiburi]

I suggest you to check the dc resistance at voice coil exit before proceeding, the repair is not difficult, it could be easly done if you have little manual skills, sure is much easyier than removing the cone assembly, probably there are some tutorial videos online about the wires substitution.
Good luck!

[budney]

I finally got round to getting these monitors up and running. Took a while to refinish the cabs and repair the crossovers.

I got the aftermarket cone kit in the frame. I didn't have an original coil to compare it to, so couldn't comment on how close it was to the original. But getting it in the monitors, I really cannot tell the difference. It sounds the exact same to me as the original cone. It looks slightly different, the paper pulp is slightly darker than the original. When you read SoundSpeakerRepairs website, especially on their D130, E and K series kits, you can see how hard they worked hard to get as close to OEM specs as possible, so I have confidence that their other cone kits are to the same standard. It shows, as it is indistinguishable from the original.

Initially when listening to them, it felt like the 2441 on the 2311 horn was overpowering the LE15, even with the crossover on the lowest setting. It felt like it was very much stuck in the 70s, I was a bit disappointed, hardly any low end. I was thinking about maybe getting an L pad to lower the 2441 even more. But I stuck some White EQs on them, got my iPhone FFT app and got it pretty flat. They sound incredible! The low end was back, the classic JBL punch that I know and love had appeared again. I had a friend who's a brilliant engineer and has a fantastic ear listen to them, he said they were a very comfortable sound and he would have no problem working with them.

For the 2405, they came with some cheap Chinese diaphragms installed, but also came with the original blue diaphragms. The Chinese ones were terrible, straight away I swapped them out. One original blue diaphragm had quite a few dents in it, not sure how that would affect the sound, but it sounds good to me. Even though I'm sure they're quite old now, I'm happy with them. Testing the 2441, and they were a bit odd. One was distorting around 500hz, and the other one was crackling with loud volumes. I think its probably a combination of the gap needing cleaning, and the foam rotting. I forgot to swap the foam out before installing but I will order some felt and service the 2441.

Next step I think would be to recone the LE15B driver I have, and try to extract the cone assembly fully so then I can sell to the Asian market. I'm concerned that the valuable original driver will get overworked as this will be a working studio so will get a lot of use...and it also looks a little bit odd so may as well make them match. I think I need to widen them slightly as they are a bit too close together, but we will get to that eventually.

You can see the EQ curve that I used to get it flat, I'm very happy with the result. Whats strange with these EQs is that theres a peak on the low cut, so theres actually more low end if I cut it at 40 or 50 rather than leave it flat. Also I forgot with horns this efficient, the noise floor is amplified. Sounds like I will need to recap the amp (BGW 250A) too!


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[Mr. Widget]

Looks like you have made great progress! Having gone down a similar path many years ago, I would recommend adding the L-pads. I actually built custom crossovers which I thought sounded much better than the originals, but at a minimum I’d add the L-pads so you can use your White EQs for fine tuning instead of major corrections.


Widget

[Flodstroem]

Only on the LE15A. I currently only have 1 working driver, and that’s around 9 ohms. I had thought about repairing the LE15B but it’s not worth it

take a look at this post:
http://www.audioheritage.org/vbulletin/showthread.php?39303-Speaker-basket-terminals-loose-on-old-JBL&highlight=