KEF B139 possible damaged by repair service Need Advice-Help

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alou

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Joined 2019
#1
Hello,
I Have a pair of Cambridge Audio TL100 speakers that5 recently began completely renovating .Upon inspection of the KEF Drives (T27-B110-B139) i saw that the B139 woofers had cracks on the surrounding racetrack rubber .
Since i has no other option ,i cant find them new or used , i decided to give them for repair . After searching and taking advice by many Hifi locals and in forums (I am located in Greece) i was sugested to speaker only reapairman with good reputation that has a shop for 40+ years.
The guy seemed to know about these drives ,he had several in the store,and vintage speakers in general. He said that the cracks were nothing and the suspension is in excellent shape,The rubber can not be changed but he can place rubber over it or something like that.
After waiting for 3 weeks ,i called he didnt, i went to pick up the drives and saw what it looked like new rubber,since i was in a hurry,it is an Odyssey to get downtown,i took them and left.
When i got home at night i opened them and saw that the speakers were covered in a shiny sticky stuff that looks like contact or rubber cement that is shiny and sticky!

Since i dont know anything about repairing ,except changing rubber suspensions,can you please look and let me know what he has done,i believe he damaged them !!



Thanks to all


Pics :
https://i993.photobucket.com/albums/af55/aloudjlouky/KEF B139/IMG_20190602_013815_zps9fz3dtvb.jpg


https://i993.photobucket.com/albums/af55/aloudjlouky/KEF B139/IMG_20190602_013806_zpshbwq6xbe.jpg


https://i993.photobucket.com/albums/af55/aloudjlouky/KEF B139/b139-me kolla_zps1q3gbuxg.jpg
 
#5
Falcon only sells the 1044 version not the 6171,besides the point is to repair not buy new ones.The speakers are in excellent condition,only had some cracking on the surround rubber due to age.I was just wondering if the repair was done properly.The ones for sale on ebay are in horrible shape.
 
#7
Well thats exactly what happened,i covered the drives before installation to the cabinet,and the old bed sheet i used got sticky and peeled off allot of this sticky stuff specially around top or made little glue balls.look like its contact cement.

I have no choice to drive back down town (its almost an hour drive from where i live) and give them back to him to do something,even though i no longer trust him.
What a poor job,he just pooed glue all over ,that what appears to me

If things don't work out does anybody know anyone in EU who can properly repair B139 - 6171 ?
 
#8
I took the speakers back to him today ,he said the material he used is liquid natural rubber and the exceed glue like stuff is on the edges ,he will reapply the rubber to make sure everything is ok and the groove (that is what is important) is sealed like you said.Actually he said the exact words like you "The rubber surround must be sealed. Cracks allow air to escape and that ruins the tuning. If the repair job achieved sealing them, then it's good" I Dont know about added mass but he seems experienced and has good reputation. I just had never had a speaker repaired physically up until now ,i only repaired the electronic parts, or change a speaker unit completely.So i don't know much about how speakers get repaired (rubber ,cones ,spiders etc) ,thats why i asked.Well i cant avoid the dust magnet if this think remains sticky and it wont bother if you cant see it behind the grill
The pics are photobucket links, i will try to upload them here later.
I took the speakers back to him today ,he said the material he used is liquid natural rubber and the exceed glue like stuff is on the edges ,he will reapply the rubber to make sure everything is ok and the groove (that is what is important) is sealed like you said.Actually he said the exact words like you "The rubber surround must be sealed. Cracks allow air to escape and that ruins the tuning. If the repair job achieved sealing them, then it's good" I Dont know about added mass but he seems experienced and has good reputation. I just had never had a speaker repaired physically up until now ,i only repaired the electronic parts, or change a speaker unit completely.So i don't know much about how speakers get repaired (rubber ,cones ,spiders etc) ,thats why i asked.Well i cant avoid the dust magnet if this think remains sticky and it wont bother if you cant see it behind the grill
 
#10
Often there are several ways to solve a problem.

Shortest path is to replace speakers with new ones ..... if available.

Second best is repairing. With proper parts of course.
I am intrigued by LJT´s link: he calls them "spares" but pictures in page look like assembled working speakers ... or are they just exampes of speakers repaired with their parts kits?

If none of the above is available, not even a spare rubber edge to replace the old one, then third best is what your tech did, liberally coat the surround with "speaker dope", a water based acrylic sealant, chemically same as that used to waterproof ceramic tile roofs and such.
It is NOT repeat NOT white PVA "carpenter´s glue" which dries hard, throws resonance up big time and soon cracks worse than original problem.

This "Latex" (acrylic suspension in water) instead never ever dries, is always flexible and minimally alters resonance.
And it offers extra cone edge damping (it´s original purpose) which is never bad.

Yes, being sticky it´s a dust/lint magnet so do not put bedsheets, blankets, cotton balls or hair-losing-pets on them 😀

The rubber in your surrounds has not magically been "repaired", but you have a couple years extra use out of them while you hunt for replacements or sppare parts.

Being such a popular speaker sold in the thousands (or more) I don´t understand why nobody made an aftermarket reconing kit.
 
#13
Sabbelbacke said:
Are you sure there are no rubber surrounds available? Back in the days when we did reconing, I stumpled across many spare parts for older speakers - I would have to look up my contacts, but since this speaker was so common .... There should be something around in Europe...
Click to expand...
Hi,no there isn't a rubber surround for this speaker,the spare part is the whole top section with the round circle and the drum like polyester.
 
#14
JMFahey said:
Often there are several ways to solve a problem.

Shortest path is to replace speakers with new ones ..... if available.

Second best is repairing. With proper parts of course.
I am intrigued by LJT´s link: he calls them "spares" but pictures in page look like assembled working speakers ... or are they just exampes of speakers repaired with their parts kits?

If none of the above is available, not even a spare rubber edge to replace the old one, then third best is what your tech did, liberally coat the surround with "speaker dope", a water based acrylic sealant, chemically same as that used to waterproof ceramic tile roofs and such.
It is NOT repeat NOT white PVA "carpenter´s glue" which dries hard, throws resonance up big time and soon cracks worse than original problem.

This "Latex" (acrylic suspension in water) instead never ever dries, is always flexible and minimally alters resonance.
And it offers extra cone edge damping (it´s original purpose) which is never bad.

Yes, being sticky it´s a dust/lint magnet so do not put bedsheets, blankets, cotton balls or hair-losing-pets on them 😀

The rubber in your surrounds has not magically been "repaired", but you have a couple years extra use out of them while you hunt for replacements or sppare parts.

Being such a popular speaker sold in the thousands (or more) I don´t understand why nobody made an aftermarket reconing kit.
Click to expand...
What you said was explained to me by the technician,what he used was not glue ,its some kind of rubber (natural based) formula spacilay made for speakers.
You can not change the rubber or cone (there isnt a cone ,its a polyester drum) it will destroy the speaker.

He has 1-2 replacement parts which in this case its the whole top unit ,the speaker is made of 2 big parts.
But he said its not necessary because the speaker is in great shape,the rubber might have cracked in some places (like dry earth) but there was no hole or tear and the polyster drum is excellent.
I haven't heard of such procedure before but he explained it to me,i haven't connected the speaker yet as well ,since the cabin is not dry yet from re-varnish.
I saw that others around Europe do that so it cant be the wrong way.

I hope they are ok, haven't found any used ones in good shape as well.you find allot of the 1044 but not the 6171.
Since i have cats and dogs these speakers will remain in my office,which is pet free 🙂 !
 
#16
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