KEF 103.2 rebuild

[Eppie]

Decided to rebuild a pair of KEF 103.2 that were given to me. These were built in England in the early 1980s and since the woofers use a butyl surround they are not susceptible to foam rot. One cabinet has badly damaged corners and the other some swelling on the top panel likely due to moisture, so I'll have to rebuild the corners and replace the top veneer which is walnut. (Thank you KEF for maintaining a database on vintage product!)

I hooked these up to my Denon AVR and they still sound very nice. A little soft in the high frequencies (just need a bit of eq) but they are very pleasant to listen to with good bottom end for a bookshelf. Plan to give these to my daughter if they turn out ok. I've posted some photos before but I am including all photos to be complete for reference. You can see the damaged corners. The woofer is dusty but otherwise in great shape. The other woofer lost a little lamination on the cone and has a small dimple in the dome tweeter but it's just cosmetic.

The binding posts were pretty crappy back then. Very close together to use bare stranded wire and difficult to tighten. The hole is too small to replace them without routing out a larger opening. Will need to make some cables with banana plugs to go with these.

Top panel veneer is raised likely due to moisture so I will need to rout out the top inset veneer to a depth for new veneer.

 

[Pogre]

Speaker restore! This is a little bit different. No parts to source, just get the cabs whipped back into shape, huh?

 

[Eppie]

Little dimple in one dome tweeter but it's minor.

Touched up the one woofer with some clear coat to prevent any further delamination. It stands out much more in the photo. From a distance it is not very noticeable and the clear coat brought back the shine to match the rest of the surface.

Whoever wired these speakers must have been drinking too many Guinness the night before! Worst soldering job I have ever seen, including the binding posts and cross-over terminals. That will all get redone properly.

 

[Eppie]

Speaker restore! This is a little bit different. No parts to source, just get the cabs whipped back into shape, huh?

Yup. The crossovers look pretty good so I don't think I need to replace any caps. The crossovers were very well made. The wire soldering was horrible! Somebody was drunk or lazy.

 

[Eppie]

Nice thick foam insulation on the entire inside of the cabinet. Nothing behind the tweeter here, but the large piece in the second photo extends along the entire cabinet length, so single layer behind the tweeter and double layer behind the woofer. They knew what they were doing.

 

[TLS Guy]

Decided to rebuild a pair of KEF 103.2 that were given to me. These were built in England in the early 1980s and since the woofers use a butyl surround they are not susceptible to foam rot. One cabinet has badly damaged corners and the other some swelling on the top panel likely due to moisture, so I'll have to rebuild the corners and replace the top veneer which is walnut. (Thank you KEF for maintaining a database on vintage product!)

I hooked these up to my Denon AVR and they still sound very nice. A little soft in the high frequencies (just need a bit of eq) but they are very pleasant to listen to with good bottom end for a bookshelf. Plan to give these to my daughter if they turn out ok. I've posted some photos before but I am including all photos to be complete for reference. You can see the damaged corners. The woofer is dusty but otherwise in great shape. The other woofer lost a little lamination on the cone and has a small dimple in the dome tweeter but it's just cosmetic.
View attachment 49235
The binding posts were pretty crappy back then. Very close together to use bare stranded wire and difficult to tighten. The hole is too small to replace them without routing out a larger opening. Will need to make some cables with banana plugs to go with these.
View attachment 49236
Top panel veneer is raised likely due to moisture so I will need to rout out the top inset veneer to a depth for new veneer.
View attachment 49237

The bass mids are the KEF Bextrene cone B200s. Bextrene is no longer produced. Unfortunately it does not age well, evidenced by one of those cones.

Unfortunately it become brittle over time and cracks. You will need to use those speakers gently otherwise at that age those cones will crack.

 

[Eppie]

Photo of the crossover inside the cabinet and then removed for inspection. If there seems to be a lot here, that is because this model has overload protection. Excessive power causes a relay to cut out the speaker and turn on the LED on the front of the cabinet. Protection circuit is lower left in 1st photo, top right in 2nd photo. The rest is the crossover. Wire wound resistors and iron core inductors. It would have taken a lot to blow one of these.

Two resistors were coated in oxide that brushed off. It does not appear to be heat related so I think the outside coating just aged but the resistor measures fine. The caps all look good too and I'm not going to worry about any capacitance drift due to age. I suspect the variance is small enough as not to be noticeable.

 

[Eppie]

The bass mids are the KEF Bextrene cone B200s. Bextrene is no longer produced. Unfortunately it does not age well, evidenced by one of those cones.

Unfortunately it become brittle over time and cracks. You will need to use those speakers gently otherwise at that age those cones will crack.

Thanks for the heads up. I gently flexed the material between my thumb and index finger and it still has flex without feeling brittle. I tested these out back in May and played them for an entire day. Pretty loud at times too. They held up pretty well so hopefully the cones are survivors.

 

[Eppie]

First order of business was to resolder the crossover connections properly, reinstall it and cover up the openings. It pays to think these things over for a while before tackling them. Since the top centre panel was raised I first thought of routing out just the centre. The outer edges were kind of rough though and also veneer, so it made much more sense to clean off the entire top. Routing would have required making a jig but removing a couple of millimetres from the surface is a prime job for a hand plane. I used a very shallow cut so as not to tear the particle board. Got it down to the outer veneer for now and called it a night.
For you wood workers out there, that's an old Bailey No.5 that I rescued from a flea market. The brass on the sides is from an old repair. The plane must have been broken in half but whoever fixed it was a real craftsman. The bottom is nice and flat with a proper throat opening. It was a rusty mess with a cracked handle so I got it for $15. A few hours of rust removal, polishing and painting got it back into shape and the old blade still holds an edge very well. Need to find some walnut veneer this week.

 

[cpp]

call this guy, it notes he might have the speakers parts https://audioproz.com/AP.php?Prod=Speak_Parts

And this other place which I used when I rebuilt some 104/2's

KEF Replacement Parts and KEF repairing | Speaker Exchange

KEF Replacement Parts & KEF repairing | Speaker Exchange authorized KEF service centre & repair speakers with original manufacturer’s parts

reconingspeakers.com

 

[Eppie]

call this guy, it notes he might have the speakers parts https://audioproz.com/AP.php?Prod=Speak_Parts

And this other place which I used when I rebuilt some 104/2's

KEF Replacement Parts and KEF repairing | Speaker Exchange

KEF Replacement Parts & KEF repairing | Speaker Exchange authorized KEF service centre & repair speakers with original manufacturer’s parts

reconingspeakers.com

Thanks for links. I'll bookmark that for future reference. For now the blemish on the one mid-woofer appears to be cosmetic. A very thin layer of surface delamination that should not affect the sound. Have to wait and see if my repair holds up ok. Nice to know that there are parts in case one speaker goes or the protection circuitry fails. There is one integrated circuit (above the two small orange caps) that could not be substituted and the relay could be difficult to find. The rest of the parts look pretty standard although a circuit diagram would be nice.

 

[Eppie]

Some more progress on the KEFs. Top has been cleaned off with the plane and sanded smooth.

Repairing particle board corners is a pain. Plastic wood fillers will not work and just break off. The trick is to gather some saw dust (preferably from the same type of wood as the veneer) and mix in some wood glue until it forms a putty. It's very sticky and adheres very well to particle board and will not break off if you bump into it. It dries hard and sands to a smooth finish. As it will not take any stain it should be colour matched before application. Always go on the darker side when making repairs. Light coloured patches tend to stand out while dark patches look like knots or a darker patch of wood grain.

Some water damage that will be difficult to cover up. These areas tend to take stain on differently making colour matching a fine art.

Another patched corner. Once stained and coated you will hardly notice the repair. The gap in the corner edge seam took the longest. It was a small crack running most of the edge and was quite visible but too small to patch with veneer or saw dust mixture. I just happened to have some Minwax walnut coloured putty that was very fine in particle size but I had to use a jeweler's loop to get enough magnification to fill it cleanly.

Walnut veneer glued down and ready for trimming. Veneer selection sucks and we're a city of 400,000. Only walnut veneer available in town was from Lee Valley and I found out after the purchase that it's paper backed. Not ideal as the edge is exposed. Will likely leave a thin dark line after staining but hopefully not too noticeable.

 

[Mark E. Long]

Some more progress on the KEFs. Top has been cleaned off with the plane and sanded smooth.
View attachment 49479

Repairing particle board corners is a pain. Plastic wood fillers will not work and just break off. The trick is to gather some saw dust (preferably from the same type of wood as the veneer) and mix in some wood glue until it forms a putty. It's very sticky and adheres very well to particle board and will not break off if you bump into it. It dries hard and sands to a smooth finish. As it will not take any stain it should be colour matched before application. Always go on the darker side when making repairs. Light coloured patches tend to stand out while dark patches look like knots or a darker patch of wood grain.
View attachment 49480

Some water damage that will be difficult to cover up. These areas tend to take stain on differently making colour matching a fine art.
View attachment 49481

Another patched corner. Once stained and coated you will hardly notice the repair. The gap in the corner edge seam took the longest. It was a small crack running most of the edge and was quite visible but too small to patch with veneer or saw dust mixture. I just happened to have some Minwax walnut coloured putty that was very fine in particle size but I had to use a jeweler's loop to get enough magnification to fill it cleanly.
View attachment 49482

Walnut veneer glued down and ready for trimming. Veneer selection sucks and we're a city of 400,000. Only walnut veneer available in town was from Lee Valley and I found out after the purchase that it's paper backed. Not ideal as the edge is exposed. Will likely leave a thin dark line after staining but hopefully not too noticeable.
View attachment 49483

On some cracks and loose veneer on corners it’s good to use an epoxy and color match it the best you can . Super glues have come a long way for woodworking too

 

[Eppie]

On some cracks and loose veneer on corners it’s good to use an epoxy and color match it the best you can . Super glues have come a long way for woodworking too

Agreed but I'm having difficulty finding a supplier. I've seen Youtubers mix epoxy and use cyanoacrylate with the spray accelerator but none of the hardware stores carry the same stuff. Just little tubes of LePages or Gorilla epoxy or superglue. Need to go on some forums and ask local woodworkers where they get their supplies from.

Edit: Epoxy is ok for fixing veneer, but for rebuilding a broken corner it is too fluid and would need a form that does not adhere to epoxy. Nice thing about putty made from saw dust and glue is that it holds its shape.

 

[Mark E. Long]

Agreed but I'm having difficulty finding a supplier. I've seen Youtubers mix epoxy and use cyanoacrylate with the spray accelerator but none of the hardware stores carry the same stuff. Just little tubes of LePages or Gorilla epoxy or superglue. Need to go on some forums and ask local woodworkers where they get their supplies from.

Edit: Epoxy is ok for fixing veneer, but for rebuilding a broken corner it is too fluid and would need a form that does not adhere to epoxy. Nice thing about putty made from saw dust and glue is that it holds its shape.

I follow a lot of woodworking on Instagram there’s tons of ads for various glues and good tips on fixing and patching veneer. Those are nice cabinets you got there and should be beautiful when your done .

 

[Eppie]

Original finish appeared to be oil, so stained with golden oak and then oiled with teak oil. Starting to look nice. Still need to blend in the water marks better but the back panel looks pretty good

 

[Mark E. Long]

Original finish appeared to be oil, so stained with golden oak and then oiled with teak oil. Starting to look nice. Still need to blend in the water marks better but the back panel looks pretty good
View attachment 49550

I like it they’ll be gorgeous when your done .

 

[Eppie]

I like it they’ll be gorgeous when your done .

Thanks. Been wondering if there is a way to lighten the water stains. Maybe dilute some bleach with water and try and bleach some of the colour out? As soon as you re-apply stain or oil to a water damaged area, it tends to get darker quickly, so colour matching is a real challenge. It's much more noticeable in the photo than under regular lighting but I'd like to get a better match than pictured above. I don't think I'll have this issue with the other cabinet.

 

[Mark E. Long]

Thanks. Been wondering if there is a way to lighten the water stains. Maybe dilute some bleach with water and try and bleach some of the colour out? As soon as you re-apply stain or oil to a water damaged area, it tends to get darker quickly, so colour matching is a real challenge. It's much more noticeable in the photo than under regular lighting but I'd like to get a better match than pictured above. I don't think I'll have this issue with the other cabinet.

You might try acetone or gun stock whitening it will take all the oil and possibly the discoloration and leave the wood it’s natural color and won’t hurt the glue or the fixed corners .

 

[afterlife2]

Looking great man. I just saw this today. Remarkable recovery indeed. Can't wait till you jam!