Good luck. Make sure to test them before you glue in the center piece to make sure the excursion is smooth with no debris. Gently push the speaker in and out with your fingers evenly spread -don't push too hard, paper drives can be brittle and crack. See the video where I describe this process. They are worth the trouble once repaired!!
After them being stored by my aunt in a damp basement for 30 years, they were sagging a bit, and the bass rattled. Then, a faulty receiver blew the speakers with max volume. They're unusable, and they're unreparable.
Sorry to hear that. These are wonderful speakers. I would go to one of the DIY forums to see what people recommend. I'm sure there are after market replacements...I know people are doing that with the tweeters when they blow.
Manufacturers will use specific surrounds for their compliance and measurements within a drivers proposed use. As mechanical mass is related to surround weight and stiffness also, its an integral part of the driver parameters. Foam on the Kef 107 will generally be expected to last around 15 years dependant on room conditions such as heat and humidity, and how hard the speaker is driven. The 1st time my drivers foam deteriorated I managed to get four replacement drivers from Kef. A few years back the surrounds on these failed. Thats rotted foam twice within 30 years roughly. Rubber also deteriorates, it dries and cracks again dependant on conditions, though generally more robust, we still see rotted rubber and cloth surrounds on drivers. Cones also deteriorate, regardless of material the continual vibration and flexing will often affect stiffness, and the spiders also will suffer with age, losing spring and linearity. Hence why many big proffesional systems have cost effective full spider, coil, cone, surround replacement kits.
My ears tell me a well designed driver with butyl nitrate used as the surround work and sound fantastic. Cloth surrounds as well. I have always looked at foam as a cheap out on the engineering end to get the most out of sound.
@@waterlife.1905 if your thinking foam equals cheaped out on speaker design, well frankly you 100% do not know anything about speaker design. Many high end speakers used foam. In fact the majority of the CHEAPEST drivers all over the world use pleated fabric and rubber surrounds, quite frankly because they are cheaper to fabricate and usually colour sound even more. Most of us are not happy with foam in Kef and it's been a pain for every owner of a coupled cavity Kef design, but the fact is the speaker would not be +-2db right down to 18hz and capable of even lower bass, with actual pitch definition, that the majority of speakers costing even more could not acheive in its day. My preference these days would be PMC BB5's, KERR K100's but those are better speakers and costing 20k upwards and although great the lower end models simply do not drop to 20hz and lower with the ease and footprint on the 107. But going back to the 107 development, two 10" drivers with foam surrounds and paper cones were quite simply the best drivers with the best TS parameters to operate within a coupled cavity enclose and maintain the speed and cone control to allow bass and pitch definition down to 20hz. You will find Kef used foam on all coupled cavity drivers, favouring paper, due to sound quality, nothing to do with cost. Though four of these drivers from memory in the mid 90's cost around £380. Now if there was ANYTHING modern that could replace that driver within this cabinet, many AES members and professional speaker builders would have long cottoned on to it, the simple fact is for that coupled cavity we have no spec for spec replacement, if Volt's 10" drivers worked I would have dropped four in years ago, but they do not as the TS parameters are all wrong. Bear in mind spending £999 on a bass driver and sticking it in a box does not mean you have better bass than sticking a £99 bass driver in a box. There really isnt much option for a speaker with classic BBC style vocals like you get from an LS3 or Spendor BC1, with bass around 18hz at +-2db, I mena you litterally get usefull bass down to 13hz in some instances, room and equipment dependant. Show me a floorstander today that is pretty much flat from 20hz to 20khs with a easy to manage cabinet. The one failing for owners is actually the treble, some years ago I was supposed to get a pair of Raal ribbons made, it is something I may revisit. If you care to look into all the reviews and the references of the engineers who were designing these speakers and show us how you could have designed a better speaker in the late 80's, early 90's, make a video. Kef created a flagship speaker capable of some of the best bass performance in a commercial loudspeaker, capable of going down to 18hz and differentiating between tones like E flat and F. You on the other hand seem to judge a speakers quality like a hooker judges a condom, by the durability of rubber.
Thanks a lot, this is great! I just acquired a pair of KEF 107/2s of unknown history with totally disintegrated foam. Hopefully the previous owner did not blow the coils. Took all four drivers out already, using your easy to follow video, thank you. Do you know the best way to tell if the drivers are good before I bother refoaming? Can they be damaged even if the resistance looks OK?
Appalling that KEF would use foam in any of their drivers. All their earlier stuff used nothing but bextrene, vinyl and butyl rubber.Using foam was a crime against the KEF name.
Yes, you would need to remove the shims to glue the center piece which could allow the voice coil to move since the glue on the outer hasn't dried yet. You could probably do the outer surround on each woofer and by the time you finish all four, go back and do the donut on them starting with the first one you glued the outer on. It should only take an hour or two for the glue to be mostly secured but overnight will give the best bond.
What a nightmare job to have this to look forward to after purchasing used 107s. I expect better from KEF. In all their years not once did they ever even consider using foam for surrounds until the 107 ans 104/2.
It was required for the driver TS parameters to perform in a coupled cavity, the majority of audiophile speakers even more costly than Kef also used this. Remember, for 20 years after production you were still able to buy replacement matched drivers for your system from Kef. And to this day refoam kits have been available. That music lovers are still running Kef 104/2 105/3, 107 and so many other foam based Kef speaker systems is pretty good, it's a shame so many bin them due to foam rot. Remember any old speaker, even if it does not have foam rot, will probably be needing serviced, no speaker truly lasts forever while maintaining its performance, Kef Reference were often built with pair matched drivers and crossoverss to 0.5db tollerance, and Kef used to keep record of these specifications. At that time no company was offering much better, 15 years old and I ordered identical pair matched bass crossovers and mid/treble crossovers, I later also managed to get pair matched tweeters to my system, and later again four bass drivers, all before Kef eventually ended such support for the 107.
Really appreciate the video. Excellent job. Now I am going to takeout the crossovers and look for a shop to replace the capacitors.
Just got a set of these with this issue. Got the kit in the repair them and I cant wait to hear them!! Thanks for the Tutorial!
Good luck. Make sure to test them before you glue in the center piece to make sure the excursion is smooth with no debris. Gently push the speaker in and out with your fingers evenly spread -don't push too hard, paper drives can be brittle and crack. See the video where I describe this process. They are worth the trouble once repaired!!
I have had both 107 Reference and 107.2 reference and preferred the 107 first issue. Amazing speakers and they go DEEP. Actually kinda miss them.
Nicely done video.
I am happy that other people also doesnt manage to make it look perfect with no glue outside the foam surrounds :D
It's asking for an external crossover I mean it's right in front of you???
How do they sound compared to modern high end speakers?
After them being stored by my aunt in a damp basement for 30 years, they were sagging a bit, and the bass rattled. Then, a faulty receiver blew the speakers with max volume. They're unusable, and they're unreparable.
Sorry to hear that. These are wonderful speakers. I would go to one of the DIY forums to see what people recommend. I'm sure there are after market replacements...I know people are doing that with the tweeters when they blow.
Why does everyone use foam instead of butyl or cloth surrounds? Foam only lasts a short while before it will deteriorate in my experience.
Foam allows excursion -dynamics and bass.
Manufacturers will use specific surrounds for their compliance and measurements within a drivers proposed use. As mechanical mass is related to surround weight and stiffness also, its an integral part of the driver parameters.
Foam on the Kef 107 will generally be expected to last around 15 years dependant on room conditions such as heat and humidity, and how hard the speaker is driven. The 1st time my drivers foam deteriorated I managed to get four replacement drivers from Kef. A few years back the surrounds on these failed. Thats rotted foam twice within 30 years roughly.
Rubber also deteriorates, it dries and cracks again dependant on conditions, though generally more robust, we still see rotted rubber and cloth surrounds on drivers.
Cones also deteriorate, regardless of material the continual vibration and flexing will often affect stiffness, and the spiders also will suffer with age, losing spring and linearity. Hence why many big proffesional systems have cost effective full spider, coil, cone, surround replacement kits.
My ears tell me a well designed driver with butyl nitrate used as the surround work and sound fantastic. Cloth surrounds as well. I have always looked at foam as a cheap out on the engineering end to get the most out of sound.
@@waterlife.1905 if your thinking foam equals cheaped out on speaker design, well frankly you 100% do not know anything about speaker design. Many high end speakers used foam.
In fact the majority of the CHEAPEST drivers all over the world use pleated fabric and rubber surrounds, quite frankly because they are cheaper to fabricate and usually colour sound even more.
Most of us are not happy with foam in Kef and it's been a pain for every owner of a coupled cavity Kef design, but the fact is the speaker would not be +-2db right down to 18hz and capable of even lower bass, with actual pitch definition, that the majority of speakers costing even more could not acheive in its day.
My preference these days would be PMC BB5's, KERR K100's but those are better speakers and costing 20k upwards and although great the lower end models simply do not drop to 20hz and lower with the ease and footprint on the 107.
But going back to the 107 development, two 10" drivers with foam surrounds and paper cones were quite simply the best drivers with the best TS parameters to operate within a coupled cavity enclose and maintain the speed and cone control to allow bass and pitch definition down to 20hz. You will find Kef used foam on all coupled cavity drivers, favouring paper, due to sound quality, nothing to do with cost. Though four of these drivers from memory in the mid 90's cost around £380.
Now if there was ANYTHING modern that could replace that driver within this cabinet, many AES members and professional speaker builders would have long cottoned on to it, the simple fact is for that coupled cavity we have no spec for spec replacement, if Volt's 10" drivers worked I would have dropped four in years ago, but they do not as the TS parameters are all wrong. Bear in mind spending £999 on a bass driver and sticking it in a box does not mean you have better bass than sticking a £99 bass driver in a box.
There really isnt much option for a speaker with classic BBC style vocals like you get from an LS3 or Spendor BC1, with bass around 18hz at +-2db, I mena you litterally get usefull bass down to 13hz in some instances, room and equipment dependant. Show me a floorstander today that is pretty much flat from 20hz to 20khs with a easy to manage cabinet. The one failing for owners is actually the treble, some years ago I was supposed to get a pair of Raal ribbons made, it is something I may revisit.
If you care to look into all the reviews and the references of the engineers who were designing these speakers and show us how you could have designed a better speaker in the late 80's, early 90's, make a video. Kef created a flagship speaker capable of some of the best bass performance in a commercial loudspeaker, capable of going down to 18hz and differentiating between tones like E flat and F. You on the other hand seem to judge a speakers quality like a hooker judges a condom, by the durability of rubber.
Thanks a lot, this is great! I just acquired a pair of KEF 107/2s of unknown history with totally disintegrated foam. Hopefully the previous owner did not blow the coils. Took all four drivers out already, using your easy to follow video, thank you.
Do you know the best way to tell if the drivers are good before I bother refoaming? Can they be damaged even if the resistance looks OK?
Appalling that KEF would use foam in any of their drivers. All their earlier stuff used nothing but bextrene, vinyl and butyl rubber.Using foam was a crime against the KEF name.
I agree 100 percent. I use KEF Calindas for decades. No problem as material is concerned.
Any reason to not glue the center piece the same time as the outer ring?
Yes, you would need to remove the shims to glue the center piece which could allow the voice coil to move since the glue on the outer hasn't dried yet. You could probably do the outer surround on each woofer and by the time you finish all four, go back and do the donut on them starting with the first one you glued the outer on. It should only take an hour or two for the glue to be mostly secured but overnight will give the best bond.
How I can buy them ?
Great video. What kind of glue were you using?
It is supplied with the refoaming kit from Midwest Speaker Repair. Seems kind of like Elmers but no idea.
What a nightmare job to have this to look forward to after purchasing used 107s. I expect better from KEF. In all their years not once did they ever even consider using foam for surrounds until the 107 ans 104/2.
It was required for the driver TS parameters to perform in a coupled cavity, the majority of audiophile speakers even more costly than Kef also used this. Remember, for 20 years after production you were still able to buy replacement matched drivers for your system from Kef. And to this day refoam kits have been available.
That music lovers are still running Kef 104/2 105/3, 107 and so many other foam based Kef speaker systems is pretty good, it's a shame so many bin them due to foam rot.
Remember any old speaker, even if it does not have foam rot, will probably be needing serviced, no speaker truly lasts forever while maintaining its performance, Kef Reference were often built with pair matched drivers and crossoverss to 0.5db tollerance, and Kef used to keep record of these specifications. At that time no company was offering much better, 15 years old and I ordered identical pair matched bass crossovers and mid/treble crossovers, I later also managed to get pair matched tweeters to my system, and later again four bass drivers, all before Kef eventually ended such support for the 107.