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KEF 105/3 refoam and a problem
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GTIanz
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PostPosted: Wed Jun 24, 2015 11:50 pm    Post subject: KEF 105/3 refoam and a problem Reply with quote

Scored a pair of KEF 105/3's for a good price. I've always wanted a pair as I love the very original and unique design characteristics of KEF speakers.

They are in great shape but had the expected woofer foam issues.

I have an account and thread over at audiokarma.org that I decided to bring here for additional help and future reference.

I am experiencing a problem with one of the uni-q drivers and hoping someone here has some suggestions. The tweeter is fine.... the problem is distortion/resonance at what seems like the low frequency reproduction of the midrange driver.

I have removed the driver (twice). I'm not noticing a rub in the voice coil. And it doesn't sound like the typical buzzing associated with a voice coil. It also doesn't sound like a blown driver as it only seems to impact certain frequencies and some songs sound fine.

Anyone have any suggestions? At this point I'm going to pull the driver again and take it into a local repairman.

I was considering the possibility that this isn't an issue with the driver at all but, potentially crossover components that may have fallen out of spec and are allowing too broad of a frequency range to the midrange?
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GTIanz
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PostPosted: Wed Jun 24, 2015 11:53 pm    Post subject: Reply with quote

Documentation of my rebuild:

Got them moved into the house and hooked up for a short audition. Very interesting comparing them to my Infinity RSII's.

Simple and quick comparison; with no placement adjustments. Will take a lot more time and work to make a thorough comparison.

The Kef's were much more accurate and crisp in the midrange. The bass is tighter although the infinity's had quite a bit more bass output. For me the tweets were a tossup. My brother said the Infinity's tweeter sounds harsh....surprised me as I've never felt that to be the case. I didn't turn the Kef's up much to see how they sounded at higher volumes given the woofer surrounds.

My initial impression is that both of these speakers are going to excel in different areas with different types of music. Probably going to come down to a matter of taste and music preference.

As promised photo's:










Overall they are in excellent condition given their age! Wiped them down with a damp cloth. There are a few small dings and scratches. But, there are no dents or gouges. They should be very easy to clean and touch up. The plastic grill frames are 100% intact but the cloth needs to be replaced as it has pulled loose in a couple of places (I'll see if I can't clean it up and re-attach in the loose places first). And, of course I need to replace the woofer foams.
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GTIanz
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PostPosted: Wed Jun 24, 2015 11:57 pm    Post subject: Reply with quote

These awesome instructions were sent to me by canuck and definitely helped in the disassembly of these speakers.

Author Jay:

Needed tools:

stereo/music

work bench

lots of light(s)

2 pieces of 2x4 (or equiv), each covered with a towel/rag

baggies

felt pen

digital camera

deep sockets (1/4 drive). Do not use a cheesy set. Sockets/extensions falling off can hurt speakers.

hex drive

phillips screwdriver

small needle nosed pliers

soldering iron/solder

Practice the mantra: Do everything slow. Do not poke speakers. Repeat throughout entire process.

Start:

1. Remove speaker grill, store in safe out of the way place

2. Put two 2x4s on table, cover with cloth, lay 105/5 face up on the 2x4s (2x4s are to keep speaker posts

on back of speaker from hitting).

Remove mid/tweeter assembly (pod)

3. Remove 4 fasteners (hex drive) attaching mid/tweeter assembly. Note at each fastener location is a

bolt, spacer, and washer (washer may be stuck to pod assembly). Bag and mark.

4. Carefully lift the mid/tweeter assy straight up just a little (approx 1.5 inch), rotate assembly slightly, gently

set down. The idea is to locate the electrical connector.

5. Grab white connector at each end with thumb and forefinger, rock back and forth and pull downward

gently, and remove connector. Note: My first time removing this connector I battled it (I did not rock it) and

broke off some of the pod connector black plastic tangs.

6. Remove pod. Note this changes the CG of the speaker * if your speaker is hanging over the table make

sure it doesn't tip. Store pod in safe place. Note also metal washers on back of pod (at each fastener hole

* they may or may not be loose).

7. Take pictures, especially noting upper woofer and wire (color) connections. Note wire run path.

Start woofer access

8. Remove white stuffing above top woofer. Note that stuffing is not pushed against speaker cone, but

rather is located above the foam ring attached to the cabinet inside.

9. Locate the bottom panel of the speaker. Remove the 8 phillips screws.

10. Gently pull bottom panel out. This panel has a crossover and wires attached to it. Take a picture,

make a sketch of the wire (color) connections. Remove all 8 spade connections. I have bent thing like this

in the past. I remove very genty, rocking back and forth, while supporting the corssover board

at the spade location.

11. Store bottom panel in safe place. Interesting to note that KEF makes (or has made for them) their own

capacitors.

12. Remove white stuffing. Take pictures. Note wire runs.

Remove "woofer rod"

13. Recon. Locate bottom woofer, note bolt head protruding out the bottom. A similar bolt is installed in

the upper woofer, only on the top woofer the bolt head is inside the the middle top of speaker.

14. Warning warning warning: speaker damage potential. Go slow. Note also that speaker magnet likes

to attach to metal tools. At upper woofer, use 10 mm socket (with extension) and attach socket to bolt head

inside speaker center. Carefully loosen and remove bolt.

15. At lower woofer bottom, use socket to remove bolt. While doing this support rod in other hand. Do not

let rod poke speaker. Carefully remove rod. Bag/mark parts.

Upper woofer removal

16. Recon: Upper woofer held in place with 3 studs on upper surface. Note bottom of woofer (remember,

photos), especially location of terminals. When reinstalling woofer note to ensure terminals are in same

location. Also note (at least on mine) that wire runs are tight. Accordingly, rather than clip wires I chose to

desolder.

17. Clip or desolder wires at speaker teminals. Warning warning: if desoldering, careful of solder falling

onto speaker. Also note that speaker magnet likes to attrack soldering iron. To desolder I used strategic

light, needle nosed pliers (to pull on the wire), and careful placement of the solder gun. Slow. Careful.

Think. Do not hurt speaker. I considered as an option leaving wires intact. However they are glued in

place on their path to the bottom crossover area and I determined it would be very difficult to free them.

18. At upper surface use deep 7mm socket (with extension) to remove nut, lock washer, nut, and washer

at each of the three stud locations. Careful, slow, do not hurt speaker. Note the torque of the nuts as you

remove them (they are not installed too tight * this is noted since later you will reinstall these and they ride

against rubber * it is a bit difficult to gauge how much torque to use). Or, perhap more intelligently, eyball

how the speaker rubber grommets are compressed (before you loosen anything) * when you reinstall these

you will want the rubber grommets compressed about the same. Bag/mark parts.

19. Remove speaker by carefully (one hand on back of speaker, other on front) pushing down. Do not

harm speaker. Slow. Careful of the studs. The foam attached to the side of the cabinets gets in the way a

bit, but foam removal is not required. Work it slow. Carefully pull speaker up and out. As I am a bit anal I

marked mine (using felt pen) with speaker serial number and "upper". Put speaker in safe place.

Lower woofer removal:

20. Note woofer crossover mounted below lower woofer on back panel of cabinet. Take pictures. Note

wire color connector locations (make diagram/sketch).

21. Gently remove lower woofer speaker connections (spades) from crossover (on mine these were red

and black wires).

22. Use socket to remove nut, lock washer, nut and washer at each of the three locations. Slow, careful. If

confused by my "rubber compression" comment in item 19 above * you are now smarter (having removed

on woofer already) and can look at these better prior to removal to gauge rubber. Bag/mark parts.

23. Speaker is removed carefullly upwards. Note cabinet particle baord crossmenber. Also note cabinet

cutout for speaker. I had to (careful careful careful * do not poke speaker * watch fingers) face speaker up

(cone up) * slide up and over particle board crossmember, then rotate and remove through cabinet cutout.

Slow slow slow.

Reassembly:

1. Reverse order above. Note: Start with lower woofer. If you install upper woofer first you cannot fit lower

woofer into cabinet.............Also, good time to look at earlier photos to acquant yourself with positioning of

things.

2. Lower woofer. Slow baby steps. Slide down into cabinet, rotate cone upwards, slide woofer past

particlae board crossmember * be careful both of wires/terminals of woofer and also existing wires in

cabinet(upper woofer wires). Feed speaker wires through bottom, as you get close to studs you can use

one hand through bottom, one through cabinet front. Also, as you slide speaker onto the mounting studs be

gentle and ensure the speaker rubber grommet does not come off.

3. Remember, flat washer against speaker, then nut, lock washer and second nut. Tighten to compress

rubber grommet (as seen during disassembly). Or SWAG it, just don't kill the rubber.........

4. Upper woofer.

5. Solder

x. Bottom cavity * Before you reinstall this ensure you have attached metal rod between woofers. install

white stuffing, reconnect wires, reattach bottom panel.

Related stuff:

B200 woofer center dust cap repair

1. Order replacement dust caps, white glue (paper cone), and black glue (plastic) from Midwest Speaker

Repair.

2. Remove old dust cap. I used a rounded blade exacto knife and methodically worked my way around

and around the speaker cutting litttle bits at a time. I found that pulling up from the cone was bad (cone

paper wanted to pull up) * I worked the blade sideways. Get some stuff on the blade, wipe it off, get stuff on

the blade, wipe it off, etc. I declared it done when I had worked the paper cone surface down flat. Residual

glue and some debris was left, but not bad. I scraped the center plastic ring surface clean with a flat

screwdriver, and then a flat exacto blade.

3. Glue on new dust cap. Using small bottle white glue came in, I laid down a small bead along the cone

along the line of the previous glue. I also coated the outside edge of the new dust cap. Using the small

bottle the black glue came in, I put a slight bead on the speaker plastic center ring, and then a slight bead

along the inside edge of the new dust cap. I carefully positioned the cap over the speaker and set it down

gently. I then moved it to align in the center and pushed down to set the "black glue" portion. To get the

outer ring of the dust cap to attach to the cone I had to gently lift the cone up. I patted the edges with q*tips

(swab end or bent in half using the stick). I had to monitor/tweak the speakers for a bit until the glue set up.

Of course the more I did the better I got.............
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GTIanz
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PostPosted: Wed Jun 24, 2015 11:58 pm    Post subject: Reply with quote

And the fun has begun on my pair:









My sad post op helper:







The foam is completely shot on all drivers. A light tap anywhere and it breaks.





I'm sure there are more difficult projects out there. But, this one is intensive. Soldered speaker leads have to be done inside the cabinets. Removing the lower woofer was close to impossible with all the dampening material in the port chamber (All foam is glued in). All said I think it took me about 2 hours to get the first speaker disassembled. Sure the second one will go more quickly. time to order the foams and see if I should be attempting projects like this. Wish me luck!
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GTIanz
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PostPosted: Thu Jun 25, 2015 12:02 am    Post subject: Reply with quote

Embarrassing, but I left this part as is:

Ok I have ventured into territory that is making me very uncomfortable. I want to try to replace the likely dried up ferro fluid.

But, these things are assembled like tanks. Some seriously tight tolerances and glue everywhere. Don't think these things were built to be serviced. On one of the cabinets I can't even get the aluminum cap off.

Does anyone know how to get the Uni-Q driver out of the damn cabinet?






Edit: figured it out. The uniq and likely the midranges aren't even screwed in. They are coupled to the cabinet via the aluminum caps on the rear. The drivers themselves can be pushed out the front of the pod quite easily.
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GTIanz
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PostPosted: Thu Jun 25, 2015 12:05 am    Post subject: Reply with quote

This part of my build I still have questions about. Has anyone attempted replacing the ferro-fluid on 105/3 uni-q tweeters? Do these tweeters have the same problems of drying out like the 104/2?

Quote:
I don't think you will need to do the fluid on those tweeters. They don't dry out like the 104/2 tweeters do


Can this be confirmed? Honestly, I couldn't even find any information as to whether or not these tweeters have ferrofluid. What I did find is confirmation that 20-25 year old ferrofluid will likely have dried out by now.

Given that they are essentially unobtanium I think that I'm going to take your advice and simply put the one I uninstalled back in. Don't think I want to risk destroying this tweeter by taking it apart to find out.



If anyone does decide they need to do this and wants to remove the tweeter it is pretty easy.
1. On the very back of the driver there is a plastic cap (alignment cap) and a screw - remove the screw and pop out the cap.
2. The black wire snaking out the back is the tweeter leads. Mine was glued to the magnet beneath some foam (also glued).
3. I had to cut the wire lose of the foam and then gently pry the wire lose from the magnet.
4. de-solder the tweeter leads as shown above (don't need to do anything with the midrange leads)
5. Now simply pick up the entire driver holding the magnet. Place your your fingers inside next to the tweeter. Somewhat gently push the tweeter out through the hole in the rear of the speaker.
Only thing holding in the tweeter after removing the screw/cap is magnetic force.





I don't even know which section should be separated. I watched video's of the T33 tweeter and it looked pretty easy. Is there an exploded diagram of the T25 SP-1240 tweeter that anyone has seen?
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GTIanz
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PostPosted: Thu Jun 25, 2015 12:14 am    Post subject: Reply with quote

I ordered the refoam kit from Springfield Speakers off of ebay. Nice packaging.



Spent a couple hours cleaning up the woofers last night and I still have a couple more hours of to go. Hopefully I can get the outer surrounds done today/tomorrow.





Glue residue removal. The glue on these woofers is still sticky and refuses all attempts I make to take it off.

I got the edges easily simply using my fingers and a little water to clean my fingers. Easy on the edges but, it doesn't work very well when the glue can stick to the cone at the centers.

I have tried pure isopropyl alcohol, crud cutter , and windex. None are breaking down the glue. I'm going to try to remove a little bit more but more than likely I'll just use the old glue as a guide for the new donuts.



edit: Taking extra time and being patient I was able to remove most of the glue with pure isopropyl alcohol. Using a q-tip I'd apply the alcohol to the glue - let it sit for 30 seconds or so and then slowly use my thumbnail to push/roll the malleable glue until it accumulated enough to pinch off. Rinse and repeat. Think it is impossible to remove all the glue and I'm not sure one would want to. The alcohol on a paper towel is also very effective at cleaning glue residue off the basket.
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GTIanz
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PostPosted: Thu Jun 25, 2015 12:15 am    Post subject: Reply with quote

found the crossover schematic for the 105.3's at:

[URL="http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=250"]www.hifiloudspeakers.info/[/URL]


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GTIanz
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PostPosted: Thu Jun 25, 2015 12:16 am    Post subject: Reply with quote

Finished everything up and got the speakers put back together without too much trouble.

The good news:
All woofer re-foams went smoothly. No rubbing on any drivers. Probably not the prettiest job but not bad for my first re-foam IMHO.


I had read somewhere else that 3 guides worked well for them. The voice coil gap is tight....I couldn't get a 4th piece in. Inserting the guides was also a bit of a challenge as the center post blocks direct access to the voice coil gap.

I used a very small flat head screwdriver to nudge the bottom of the guide into the gap.

When gluing in the donuts large sockets are very helpful to hold down the center of the donut.

I'm also making progress on the grills. The glue supplied with the refoam kit is working very well.


Earlier I complained about how difficult it was to de-solder the woofer leads inside the cabinet. If I were paying attention at all I would have noticed that the lower woofers can easily be removed without de-soldering!



After noticing this I pulled the leads and re-attached outside of the cabinets. Made the re-install much easier.
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Last edited by GTIanz on Thu Jun 25, 2015 12:38 am; edited 1 time in total
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exkefman
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PostPosted: Thu Jun 25, 2015 12:29 am    Post subject: Reply with quote

Hi,

That's a long post.

Glad you've made progress on the re-foam side.

For the "questionable" Uni-Q driver, to eliminate the drive unit, I would just swap the entire front "assembly" (1x Uni-Q + 2x Lower MF units) as it uses a plug in connector.

If the "issue" switches to the other main cabinet, it's within that front assembly. if it "stays" with the original main cabinet, it could be something that is loose and resonating at a specific frequency.

I very much doubt the x-over is at fault, as the solder joints are usually pretty much "bomb-proof". Likewise the inductors are held with ty-raps, so you could check those are still "firm".

EDIT: If you found some coil rub, then be careful - it might just be some grit or dust that is caught up...with the tweeter disconnected, you could try running some very low level (enough to make the cone move a little) music signal into the upper-midrange drive unit for say 10 minutes, keeping the drive unit face up and resting on it's magnet - so the drive unit will be moving slightly and if there is debris in the gap, it might just fall down into the magnet gap.
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GTIanz
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PostPosted: Thu Jun 25, 2015 2:23 am    Post subject: Reply with quote

exkefman wrote:
Hi,

That's a long post.

Glad you've made progress on the re-foam side.

For the "questionable" Uni-Q driver, to eliminate the drive unit, I would just swap the entire front "assembly" (1x Uni-Q + 2x Lower MF units) as it uses a plug in connector.

If the "issue" switches to the other main cabinet, it's within that front assembly. if it "stays" with the original main cabinet, it could be something that is loose and resonating at a specific frequency.

I very much doubt the x-over is at fault, as the solder joints are usually pretty much "bomb-proof". Likewise the inductors are held with ty-raps, so you could check those are still "firm".

EDIT: If you found some coil rub, then be careful - it might just be some grit or dust that is caught up...with the tweeter disconnected, you could try running some very low level (enough to make the cone move a little) music signal into the upper-midrange drive unit for say 10 minutes, keeping the drive unit face up and resting on it's magnet - so the drive unit will be moving slightly and if there is debris in the gap, it might just fall down into the magnet gap.


Those are excellent suggestions! I will try both!

If the midrange is "blown" can it be repaired?

It does sound more like an issue at specific frequencies/tones. The trumpet at the beginning of Dire Straights - Your Latest Trick sounds terrible with the resonance.
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exkefman
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PostPosted: Thu Jun 25, 2015 11:06 am    Post subject: Reply with quote

GTIanz wrote:
Those are excellent suggestions! I will try both!

If the midrange is "blown" can it be repaired?

It does sound more like an issue at specific frequencies/tones. The trumpet at the beginning of Dire Straights - Your Latest Trick sounds terrible with the resonance.


If depends....you can contact KEF service dept in UK (or your local distributor, if you are not in UK) and see if they have any spare parts, as I don't know which drive units they still support (after they moved drive unit production from Maidstone to China).

It could be that some parts are still available, or they might offer alternatives...ask them also for a copy of the 105/3 Service Sheets - which I wrote about over 20 years ago. This might help you with re-assembly Smile

Worse case, is that you might need to find a s/h drive unit from a speaker that has been cannibalised for spares. Obviously, if you can get 2 of the same drivers from the same donor speaker, then at least you can still retain the "pair-matching" between drive units. Otherwise you may have to accept that this has been lost...after all, the speakers are over 20 years old !!

The other key thing to be aware of is this: The Coupled Cavity Bass loading is very dependent on the integrity of the seals around the bass units. The bass units sit on small rubber rings, which decouple the drive unit from the enclosure, but they are only done up "so tight" as to prevent air-leaks but also so that they don't then become "coupled" to the cabinet. If the bass unit mounts are not done up enough you'll get air leakage and you'll lose bass performance....do them up too tight and they'll be too much energy put into the cabinets.

Likewise, be careful as you tighten up the Force Cancelling Rod, as this will also affect the the bass units mounting.

It's a tricky speaker to put together...and even the KEF production guys sometimes had issues - for a "layman", it will test your patience.
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speakerguru
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PostPosted: Thu Jun 25, 2015 5:05 pm    Post subject: Reply with quote

GTIanz wrote:
If the midrange is "blown" can it be repaired?

Yes, but you'll need a new dustcap and you have to really want to do it (like when you've made just enough prototypes and one develops a rub or buzz). The moving parts can be removed. First cut out the dustcap without damaging the cone, soften the spider adhesive using MEK or similar. Lift, cleave or cut the softened bond using a scalpel. De-solder the leadout wires/braids and finally lift the surround. The paper ring between surround and chassis should de-laminate. Lift the whole lot out. Clean the gap, re-assemble using plastic shim to centre the voice coil. Re-fit dustcap

GTIanz wrote:
It does sound more like an issue at specific frequencies/tones. The trumpet at the beginning of Dire Straights - Your Latest Trick sounds terrible with the resonance.

Sometimes a foreign body, which is always magnetic (Murphy's law), will pop in and out of the gap causing intermittent noises. Without hearing a sine sweep it's impossible to say.
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exkefman
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PostPosted: Fri Jun 26, 2015 2:57 pm    Post subject: Reply with quote

Hi SG,

It's the "upper" MF unit on the 105/3 that has the issue...so it doesn't have a dust cap....!!
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GTIanz
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PostPosted: Thu Jul 02, 2015 9:54 pm    Post subject: Reply with quote

exkefman wrote:

If you found some coil rub, then be careful - it might just be some grit or dust that is caught up...with the tweeter disconnected, you could try running some very low level (enough to make the cone move a little) music signal into the upper-midrange drive unit for say 10 minutes, keeping the drive unit face up and resting on it's magnet - so the drive unit will be moving slightly and if there is debris in the gap, it might just fall down into the magnet gap.


Update:

I finally found some time and removed the Uni-q driver. I tried placing it face up and applied full range music to the midrange. The distortion was very evident even at modest volume levels.

I've called a speaker repair facility up in Seattle Washington. Turns out that they are very familiar with KEF reference speakers. I'm going to send the driver to them and hope that they can repair it.

The person I spoke with was honest and stated that there is the possibility that it won't be repairable.
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