KEF 104.2 question

The foam surrounds that ride up and down the rod in my 104.2's are starting to rot. How important are these and can they be repaired? If so how do you disassemble this speaker? My motivation level went down considerably since I picked up a mint pair of ADS 1290 II for $170!

KEF 104/2 - anybody refoamed the woofers?

Hi,
I bought a pair of KEF 104/2 reference series speakers. The mids and highs and even the cabinet veneer are all in good to better shape.

The two bass drivers in each cabinet have a foam surround in the center and travel on a bar, as seen in this photo:
http://www.hificlub.co.kr/upn/0808/brd_10180/L1020453.JPG

I bought a pair of inner foams from Simply Speakers but they come with generic refoaming instructions only.
Has anybody done this and have you found the best way to remove the speakers from the enclosure?
Any hints on the foaming job?

Thanks in advance,
audiodon657

Don't fix them. They are just dust cover and will not affect the sound. I own a pair of 104.2 myself and didn't bother refoaming them.

Camper,
Did you have them when the donuts were intact?
If so, do you find the bass a tad diminished now compared to how they were before?
I have considered leaving them because even as they are they ain't bad, but I find the bottom octaves a tad rolled off compared to the exceptional midrange. Then again, I never heard them back in the day.
Or is looking for bass like I get from my Ohm Walsh 4s an unfair test?
P.S.
I have two Hsu VTF-2 subwoofers to pick up the bottom end from 60hz on down. I was looking for bass in the octave from about 50-60 to 125 hz.

Yes, DO replace the donuts!! They are part of the suspension, the cone will sag a bit without them. More importantly, they are part of the seal of the woofer chamber. Without the donut, the chamber is not totally airtight.

The bass may sound a little louder without them, but it will not be crisp and articulate as it should be. The 104/2 starts rolling off at 50Hz, but what is there should tight and super-quick.

I've restored about 5 pairs of these now, and awhile back I posted a tutorial of sorts on disassembly. Do a search and see if you can find it. If not, let me know.

The donut dust caps should be replaced, not for airtightness but to keep dust and rotting foam from clogging the voice coil. If you choose not to replace, the chamber(ported vent) should be plugged when not in use. A careful vacuuming would also be suggested. It is a pain in the ass to dismantle the cabinet to get at the bottom driver and I jettisoned my attempt as I felt I was jepardizing the cabinet's integrety by doing so. On one of my pair of 104/2's I made a cut in the new dust cap and installed without removing the drivers. Bottom line it seem to work fine. Have fun!

I disassembled both mine last night according to brassteacher's instructions. I partially cleaned all four B200 drivers, but haven't removed all the glue yet to put the donuts on.
From what I can see, this project will take many days. The initial disassembly took an hour and a half on the first one and 45 minutes on the second. What's not stated is that the rod connecting the B200 drivers is bolted to both and must be unbolted from both. I suspect that it wasn't stated because it appeared obvious, but it wasn't.

Gaskets are a problem and I'll be making some additional ones for reassembly. Additionally I will have to find replacements for the three bolt gaskets on each driver. I'll be going to the local fix it shop to find something.
Estimated # of days from disassembly to reassembly: 5
Value: high.

audiodon657 said:

I disassembled both mine last night according to brassteacher's instructions. I partially cleaned all four B200 drivers, but haven't removed all the glue yet to put the donuts on.
From what I can see, this project will take many days. The initial disassembly took an hour and a half on the first one and 45 minutes on the second. What's not stated is that the rod connecting the B200 drivers is bolted to both and must be unbolted from both. I suspect that it wasn't stated because it appeared obvious, but it wasn't.

Gaskets are a problem and I'll be making some additional ones for reassembly. Additionally I will have to find replacements for the three bolt gaskets on each driver. I'll be going to the local fix it shop to find something.
Estimated # of days from disassembly to reassembly: 5
Value: high.

Click to expand...

Don't bother buying gaskets! I use 1/4" thick by 3/8" wide soft weatherstripping, the kind that is so dense the "bubbles" are basically invisible. I just apply it right over the old gasket, no problem. I also reseal the upper and lower chamber hatches with it.

While you have the cabinets apart, check that the two seams down the front of the cabinet, on the bottom, have not opened up. To be safe, it's worth taking a syringe of wood and/or elmer's glue and running a bead down the seam from the outside.

Also, check the ports to make sure they are not coming loose. If they are, even just a little bit, pull them and reglue them. A lot of people assume the bass is distorting, when it's really just those port tubes buzzing.

If any of the old donut has gotten down into the voice coil gap, don't panic, just lie the driver down, facing up, and drive it with an amp/signal generator of some sort that will give it a decent workout. I actually use an old Lionel train transformer for this. It'll put out 60Hz, from 0 to 18 Volts AC. Let it play, and when a piece of the "gunk" gets worked through the coil, you'll hear a little "pop", when all stays quiet, the speaker is fine. The train transformer is also perfect for working in the new donut after installation, or for working in any speaker surround replacement project.

brassteacher,
I've got a question about the three grommets around each bass driver. These are all crushed, split, or broken and in poor enough shape that I can't tell if they were originally irregularly shaped on one side or not. It does appear that they were custom grommets with the washer embedded into the rubber, but I can't be sure. Weather, sound, and years could have simply made them appear that way.
I've found some grommets that fit at my local hardware store, but the sides of the grommets mirror-image and they will make the drivers stand off from the mounting point by about 1/8th to 1/16th of an inch. I can't seem to remove all the adhesive from the paper on the cone. I'll contour it so it's not bumpy and apply the new adhesive over it.

1. Are the originals irregularly shaped grommets with much less rubber on the underside of the mounting hole and a washer embedded into the top half?
2. Would it make sense to use the replacement grommets I've found?
3. If the answer to 2 is yes, should I fill the gaps between the speaker basket and the chamber with gasket (weatherstripping)?

addition later that same day: I see that some of drivers have weatherstripping around the back of the drivers where they drop into the hole and the stuff gets compressed by tightening the pole-piece rod bolts. I'm going to get a dozen grommets and I'll use the same 3/8 one side glued rubber weatherstripping I plan to use on the hatches.

The bottoms look Ok, but I'm going to put a bead of glue on them anyway. Tonight I may do the refoaming. I waited for the alcohol to dry after working off the old foam stuck in the glue on the B200 driver paper. Now it's dry.

Do you run-in the drivers with a signal generator or no because it's the inner annulus and not the outer ring? I've got an old train transformer for an HO set. Just connect the wires that went to the train tracks to the driver and crank it slowly?

audiodon657 (the other (and hobbyist) Don in this exchange)

The original grommets were normally-shaped grommets. Pressure from tightening them at the factory "imbedded" the washer into them. So yes, normal replacement grommets should be fine.

Fill any gaps between speaker gasket and chamber with weatherstripping, yes.

WARNING: Do NOT use the transformer from an H0 trainset! Those put out DC current, and could quickly fry your voice coils! Lionel transformers put out AC current, at no more than 18 Volts, so they are perfectly safe. You can skip that step altogether, I just do it to check my work and make sure I haven't screwed anything up before I get the drivers remounted.

Here are links to the original threads where brassteacher described his KEF 104/2 disassembly process. I add these for completeness. His tutorials sure did help me.
http://www.audiokarma.org/forums/showthread.php?t=213972
http://www.audiokarma.org/forums/showthread.php?t=164605

I'll run them in after assembly with noise from between FM stations then. Thanks brassteacher.

I have completed the refoam of the inner annulus (annuli?) of my four B200 bass drivers. They move to the inner and outer extremes without rubbing or without exposing missed glue spots in the foam.

I started reassembling my 104/2s but I have been sidetracked. Instead of rushing to completion, I am running a bead of carpenter's glue around the inner chambers tonight and along the bottom seams. The bottom seams I will also clamp after gluing.
This weekend I will put new weatherstripping around the driver baskets and the chamber doors while putting the drivers back in.
I'm snapping pictures as I go for those interested and those in the future who may be interested and I will post them all after reassembly when I start run-in. Hopefully there won't be any unforeseen snags.
audiodon657

I have completed my refoam, reglue, redo, and reassembly. Here are some pictures.
I disassembled the speakers, glue sealed the upper and lower bass chambers, clamped and glued the bases, refoamed the B200 driver, tightened the B110s and T33s, put new strip foam everywhere, got new grommets for the B200s and reassembled them.

One problem. One of the B110s in one d'appolito array buzzes. I believe the voice coil is compromised. How do I get it apart? Does anyone know of a reconer? What am I in for here?

Don

Could there be a rub between magnet and coil? I had an old speaker with corrosion on the magnet. A quick run of fine sandpapre in the gap and it was all set.
These look pretty different though.
John

Folks,
I'll try not to gush here, but it'll be hard.
After putting my 104/2s back together, I discovered that one of the B110s in one of the D'Appolito midrange pods had a bad KEF B110 driver.
I bought a midrange pod off ebay, contacted the seller and bought all the spare parts he had. One pod I bought had a blown tweeter. So, these speakers now come in at close to $1000 with a lifetime's worth of spares, but I can't imagine topping them for that money.

Last night I removed my midrange pods and put in the midrange pods I'd bought. I also removed both the good and the bad tweeter from the midrange pods and put my tweeters in.
KEF 104/2s are pair matched for dB gain so it made sense to replace both pods and turn my midrange pods, one with a bad driver, into spares.
The sound?
Glorious.

I spent more than three hours listening to music last night. These speakers deserve the Enjoy the Music's product of the decade award:
http://www.enjoythemusic.com/magazine/equipment/0705/decadeawards.htm
Scroll halfway down.
The reviews speak the truth of these speakers:
http://www.audioreview.com/mfr/kef/floorstanding-speakers/104-2/PRD_119857_1594crx.aspx

What they do well is keep different instruments separate in complex musical passages. I was listening to Porcupine Tree's new "The Incident" and on track 6, the whispers and sound effects are clearly delineated.
Listening to "Blues in the Night" from Frank Sinatra's 1958 "Only the Lonely" CD on Mofi was a serious proposition with the double plucked basses coming through clearly and distinctly.
System:
2 KEF 104/2
2 Hsu VTF-2 subs crossed over at 50hz
Fisher 500-C
Lexicon RT-20 universal player.
My room rings at 54 hz. So, since the KEFs drop out at 55hz, crossing just below 55 seems to tame the ring I get if I listen to track 8 of Plant/Krauss's "Raising Sand".


If you want reasonably priced column style speakers that fit the modern form factor while exuding timeless charm, and you're not afraid to do some repairs yourself, these will be a great choice.
Next up will be light sanding and refinishing. I haven't decided whether to use Watco Danish Oil or Minwax Tung Oil.
Don

I'm glad it turned out well. These are really good speakers, although the foams are troublesome and I can't understand the MTM pods. Kinda proprietary and almost impossible to disassemble and replace the drivers.

SaSi said:

... and I can't understand the MTM pods.

Click to expand...

Hi SaSi, great to see you on this forum too. My comment is related to something that SpeakerGuru hinted this morning on the Kef forum about the marketing guys wanting the speakers to integrate in smallish modern living rooms. He designed the B300 for 80-90 litre internal volume but marketers wanted a smaller enclosure for better integration, hence the final 70 litre volume for the 105/2. Which is why I am redesigning my second set of 105/2 with that in mind. It will be as high as the original bass cabinet, slimmer but much deeper. It will be visually tiny but still with extra internal volume (90L vs 70L).

The 104/2 sounds like a speaker three times its size. Indeed, if it were designed a conventional way, it would have been much bigger. Therefore, the guys at Kef had to be quite inventive to create such a compact design. Two subs firing in a common enclosure, and isolated mids and high on the front. The 104/2 looks slim from the front but is quite deep in real. Clever. Very clever.

105/2 - A speaker that is deceptively small when you actually see one in the flesh. But it sounds so big.


107/2 - Same comment about the size. The 104/2, 105/2 and 107/2 integrate very well in any living room. They look small and sound big.

Don, there's a lot of intriguing information here...my interest for 104.2s is definitely peaked. I can listen to a pair that's local, and fully restored, so maybe I'll get around to that. I need to sell a few things before I can invest in anything else, largely because I don't have any more storage room (or the desire to store speakers that aren't as good as what I have).

I'm particular intrigued that you run them with a 500c. I can power my main speakers with that much power, but they do better on a bigger amp.

Resurrecting for Gruvin'.

If redoing again, I would add the following:
1. crossover recap from Falcon Acoustics parts.
2. tweeter fluid refill.