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Good supplier of foam surrounds and doughnuts for kef 104/2?
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MartinW
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Joined: 12 Jun 2011
Posts: 24

PostPosted: Thu May 09, 2013 3:51 pm    Post subject: Good supplier of foam surrounds and doughnuts for kef 104/2? Reply with quote

From looking through the port at the lower B200 driver I thought all was well, but sadly I'm starting to see bits of foam surround falling from the upper driver Sad.

Looking on ebay and elsewhere there seem to be a few suppliers of the foam surrounds and doughnuts, with the main ones I've found being Speaker-Repairs (UK), audiofriends and Good Hifi (NL) plus some others in the US.

Has anyone any recommendations on who to buy from please? I'm obviously after parts that are the right physical size, similar compliance to the original, and of a good quality that will last hopefully as long as the originals.

Many thanks in advance,
Martin
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zaktech
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Joined: 08 Oct 2012
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Location: Leeds, West Yorks, UK

PostPosted: Thu May 09, 2013 11:43 pm    Post subject: Reply with quote

Hi

I've used AudioFriends, their prices are very competitive (the best actually) and most importantly the product is excellent. Headrush can comment as he has seen and heard my 105/3s, and by now he should have ordered surrounds from AudioFriends as well. Replacing the surrounds and doughnuts with anything but foam types will be a huge mistake (again headrush can confirm from experience).

Cheers
Zak
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MartinW
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PostPosted: Fri May 10, 2013 12:38 pm    Post subject: Reply with quote

Hi Zak,
Many thanks for the helpful reply. Hopefully headrush and others will be able to chip in with any more thoughts.

I'd rather spend a bit more if one supplier had a better product than the other, but it's such a niche item I've not found anyone who has compared 104/2 surrounds from supplier A against supplier B. And that's assuming that they don't all come from the same source anyway, or change from batch to batch.

So, I'll give it a few more days to see if there's any more feedback and then order some. I've no intention to replace them with rubber BTW.

Thanks again,
Martin
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clubsport911
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Joined: 26 Aug 2012
Posts: 157
Location: Cheltenham, UK

PostPosted: Wed May 15, 2013 9:28 pm    Post subject: Reply with quote

Hiya. I bought mine from the UK.. (details at home). Everything was there... including shims and the right sort of glue. It's a great job and of course, whilst conducitng open heart surgery on your 104/2's you might like to see what else needs looking at.

PM me of you want some phone time - happy to help

Steve
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MartinW
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PostPosted: Sun May 19, 2013 10:00 am    Post subject: Reply with quote

Hi Steve,
Thanks for the offer. I've ordered from audiofriends so hoping the bits will turn up during next week and I'll have time to start it next weekend.
I've got the 104/2 maintenance notes and found a few write-ups of how to get at the B200s, but a chat with someone who has done it first hand would be really helpful. Expect an incoming PM Smile
Martin
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proffski
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Joined: 22 Aug 2003
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Location: Tewkesbury UK

PostPosted: Mon May 20, 2013 10:18 am    Post subject: Reply with quote

Good luck and keep us posted, some pictures of before and after would be much welcomed! Smile
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canuckaudioguy
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Joined: 16 Apr 2013
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PostPosted: Mon May 20, 2013 7:04 pm    Post subject: Reply with quote

MartinW wrote:
Hi Steve,
Thanks for the offer. I've ordered from audiofriends so hoping the bits will turn up during next week and I'll have time to start it next weekend.
I've got the 104/2 maintenance notes and found a few write-ups of how to get at the B200s, but a chat with someone who has done it first hand would be really helpful. Expect an incoming PM Smile
Martin


This might be helpful to you:

Part 1:
http://www.audiokarma.org/forums/showpost.php?p=6786459&postcount=49

Part 2:
http://www.audiokarma.org/forums/showpost.php?p=6786462&postcount=50
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MartinW
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PostPosted: Mon May 20, 2013 11:02 pm    Post subject: Reply with quote

proffski,
Thanks, I'll be taking some photos.

canuckaudioguy,
Oddly enough, I was just looking at these earlier today - a great job Very Happy - thanks for the links. Mine are the bi-wire version with foam B200 surrounds and the crossover attached to the removable base, but are otherwise the same as far as I can tell.


I'm still waiting for the bits to arrive, and in the meantime have unscrewed one of the base panels to see how 'welded on' it was. The screws were surprisingly loose and it came off easily (I was expecting a fight). Hopefully the other one will be the same.

The plan is to run a bead of wood glue around the internal seams, and have some thin foam weatherstrip to hand as replacement gasket if needed. Otherwise I wasn't intending to do anything else - it would be nice to check over the crossovers caps but I don't have an LCR meter so will leave alone for now.

TTFN,
Martin
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proffski
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Joined: 22 Aug 2003
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Location: Tewkesbury UK

PostPosted: Mon May 20, 2013 11:29 pm    Post subject: Reply with quote

My old ones are still in the family, the surrounds are good.
But sooner or later I can see myself being asked to do what you are doing.

The crossovers were rebuilt and tested to original KEF specifications which I still have somewhere. Watch this space... Smile

Bear in mind that these loudspeakers sold for around £750 in 1985, that equates to at least £1,865.00 in todays money and probably more!
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MartinW
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PostPosted: Tue May 21, 2013 10:03 pm    Post subject: Reply with quote

Hi proffski,

As I mentioned above, the surrounds and doughnuts on the lower drivers that I can see look fine - it seems strange that the top ones are in such a different state. I think it was only because I laid them on their side (to have a play with morel tweeters - perhaps more on this another day) that the loose bits of surround dropped down afterwards. So you might want to check the state of your old ones again when you get the chance?

Just out of curiosity, why did you get the crossovers rebuilt - was there a problem or just renewing ageing components? Would you suggest it's worthwhile considering testing/renewing, and if so any suggestions on how to go about it?

p.s. No deliveries today Sad The chances of a delivery tomorrow will be much higher as there will be no-one in!
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proffski
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PostPosted: Tue May 21, 2013 10:33 pm    Post subject: Reply with quote

The crossovers were rebuilt before I became the owner.
The gentleman concerned is renowned for havingf golden ears.

Only the capacitors were changed, but all important aspects like Q factor, reactance, ESR were taken into account as they all are closely affected by each other.

The best I can say is that KEFs design was respected, they were not simply exchanged for capacitors the size of beer cans costing the earth.. and they do sound glorious.
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canuckaudioguy
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PostPosted: Wed May 22, 2013 6:36 am    Post subject: Reply with quote

Quote:
canuckaudioguy,
Oddly enough, I was just looking at these earlier today - a great job Very Happy - thanks for the links. Mine are the bi-wire version with foam B200 surrounds and the crossover attached to the removable base, but are otherwise the same as far as I can tell.


No problem! I hope it helps you. Mine were a little troublesome to remove, but my friends pair was easy as pie. I guess it depends on the storage conditions on if it's going to be challenging or not.

The recap is really optional in my opinion. I did it because I wanted to experiment a little and see if it would make a difference. For me, it did. Mine are a lower serial number, in the 6000's, so I know they are an earlier unit and it's more likely the capacitors have degraded by this point. Later models I would argue it is not necessary. I did obtain a matched set of Alcap capacitors to replace the capacitors with, which are exactly the same as the originals, however it is impossible to get the original values Kef used (that is, the specific numbers they used to achieve the +-0.5dB). I did send an e-mail to them to see if I could get the information, but they said they do not have it anymore which doesn't surprise me.

In terms of difference of sound, it was not night and day, but it certainly made an improvement in some important areas such as the midrange. The ferro fluid change as well as the donut change made the most dramatic improvement, as it should. It all depends on how far you want to try and go, I decided to shoot for the last 5%. With bi-ampable models I would not touch the crossovers for at least another 5 years.
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Headrush
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Location: Nottingham

PostPosted: Wed May 22, 2013 6:18 pm    Post subject: Reply with quote

Hi Martin,

As Zak mentioned I refoamed a pair of 105/3s with rubber surrounds and have never been happy with the base. I heard Zaks same speakers with foam surrounds and could not believe the difference.

I see you already ordered your surrounds from the right place, I hope not through eBay as the postage is high. I ordered direct via email and got free post on all the kit. Unfortunately I've been so busy lately the stuff is still sitting in the box so I can't comment yet but will do as soon as I get the job done.

Good luck with your project, a job worth doing and don't forget some pics Smile
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MartinW
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PostPosted: Mon May 27, 2013 12:09 pm    Post subject: Reply with quote

Hi all,

Thanks again for the encouragement, suggestions and advice – the refoam is complete and I’m pleased I did it.

The parts from Audio Friends in the Netherlands turned up reasonably quickly, are of a good quality and fit to the B200 cone and surround. The supplied glue also does the job well, and there’s more provided than needed.

It took me Thursday and Friday evenings, most of a Saturday and then a bit of Sunday morning, so it’s not a quick job or one to be rushed. One thing that surprised me was the difference in condition between the upper and lower surrounds – both upper ones were dropping to bits whist the lower ones were still intact (but only just – it was paper thin and doing nothing as part of the suspension).

I did both speakers together, so couldn’t do a “before and after”, but the bass seems much punchier, tuneful and ‘in control’. How much of this is down to the repaired drivers, properly sealing the lower chambers, cleaning up internal connections, (and some expectation bias of course), we’ll never know, but I’m very happy with the result.

A picture of a pair before (upper one to the left, lower to the right):


And after (with glue on the doughnuts still drying):


I've got more photos and can post a simple 'how to' if anyone is interested.

Cheers,
Martin
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MartinW
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PostPosted: Sat Jun 01, 2013 11:51 am    Post subject: Reply with quote

Longish post below outlining the process which I hope is of some general interest and/or helps someone else about to take their bi-wire 104/2s apart to refoam the B200 drivers. There are lots of guides out there on refoaming the drivers themselves, so I’ve not gone into much detail on that stage. I don’t think I’ve missed anything major, but if you use a bit of common sense you can’t go too far wrong!

Getting Ready
You’ll need the following:
• Refoam kit (surrounds, doughnuts, glue)
• Allen keys
• Sharp craft knife with fresh blades
• Small paintbrush
• Philips screwdriver
• Socket set (10mm and smaller)
• Wire cutters
• Pliers
• Push on ‘lucar’ female connectors (4 of)
• Sealant (e.g. decorator’s caulk)

Some items you may need (assuming you’re not intending to do any modifications):
• Gasket strip
• Contact cleaner
• Wood glue

Other things you’ll need are time and patience, and plenty of room.

A Few Cautions
If working on both speakers at once, make a note of serial numbers so bits don’t get mixed up between them.

Use labels/sketches/photos so that you can remake connectors and put damping material, etc. back the way they were.

Be careful when removing/inserting damping materials not to push it into the cones and risk damaging them.

The mid-range drivers are not repairable, and replacement T33 tweeters aren’t available, so be extra careful removing and storing the MTM module.

Disassembly
Remove the front grille and lie the speaker on it’s side.

Unbolt the MTM module using allen keys and tilt it towards you, disconnect the push terminals for the mids and tweeter and put the module and gasket somewhere safe.


Lay the speaker on it’s back, placing a thick book or similar underneath to prevent putting weight on the speaker terminals.

Unscrew the bottom panel, pull on the spikes to release and tilt it down to the floor, then disconnect leads from the crossover as needed to get enough access. If the bottom panel is stubborn, others have suggested warming the outer edge of the panel using a hair dryer to soften the bead of mastic underneath.




Remove the foam and wadding from the top and bottom cavities, taking care not to damage the drivers.



Next, remove the force cancelling rod using a 10mm socket. This is what it looks like without the cabinet in the way:



Remove the bolt and washer from below the lower driver, then do the same for the bolt and washer hidden under the foam doughnut of the upper driver. Hold the rod as the bolt through the upper driver is removed so that it doesn’t fall within the cabinet. Don’t forget that the magnets will ‘grab’ steel tools.

Remove the bottom driver by undoing the three small nuts around the frame and remove them with the washers (the washers may be stuck to the grommets). The frame of the driver may be stuck to the gasket, so may need to be gently eased away.

Snip the orange and grey wires from the upper driver right next to the push on connectors (so they are shortened as little as possible. Then free these wires as they pass through the mastic/glue and pull them through (this is possibly the trickiest bit).



Remove the top driver, again by undoing the 3 small nuts and removing them and the washers. On mine, the gasket strip is attached to the back of this driver.

Remove old Foam and Replace
There are plenty of refoaming guides to follow – the very basic steps are:
- Remove the old foam with fingers and fingernails, then use a sharp craft knife to remove remaining old foam. Don’t try to remove old the glue as long as it’s secure and flat, but if there are lumps then pare it away to get a reasonably flat surface. Be careful not to allow bits to fall into the gap
- Clean any debris out of the gap
- Glue the surround to the cone and allow to dry
- Glue the surround to the frame, making sure that the voice coil is centred within the gap and doesn’t rub, and allow to dry
- Glue the doughnuts on, and allow to dry

The old foam on mine had turned to a sticky mush, and it makes a bit of a mess when scraping it off, so do it over newspaper to catch the bits. The old glue on mine was rubbery with consistency of stringy chewing gum.

Various photos before, during and after. I used the clothes peg method and didn’t encounter any problems centring the voice coil in the gap.








While inside the cabinet, you can take the opportunity to clean it out and make sure the chambers are airtight – run a bead of glue around the internal seams of the cabinet and renew any gaskets if needed.

Reassembly
Put the drivers in, followed by the washers and nuts but don’t tighten them yet.



Install and tighten the force cancelling rod, taking care not to damage the new doughnut foams with the rod or socket set.

Now do up the small nuts on the frames of the drivers, but don’t overtighten them. Remember that the force cancelling rod is keeping the drivers a fixed distance apart, so if you overtighten them you could end up overstressing or possibly even bending the frames. The aim is to have both drivers pressing equally against their gaskets, so don’t fully tighten the nuts on one driver first or the other driver might not seal against it’s gasket. (This isn’t quite the order in Kef’s maintenance notes, but it worked for me).

Feed the grey and orange wires from the upper driver back through the hole into the lower chamber and reseal the hole. Fix new push terminals onto the leads, and route the wires behind the foam.


Refit damping material.

Reconnect leads to the crossover. It’s worth cleaning the connectors by breaking and making the connections and making sure the connections are ‘tight’ (nip up with pliers if needed)

Close up the base, tighten all the screws.

Reconnect and reattach the MTM module, tucking the wires into the void with the tweeter so they don’t get trapped and foul the gasket.

Sit back and enjoy
Very Happy
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