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KEF 103.2 removing bass unit and accessing crossover

 
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spikeanded
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Joined: 14 Dec 2015
Posts: 3

PostPosted: Sun Dec 20, 2015 7:15 pm    Post subject: KEF 103.2 removing bass unit and accessing crossover Reply with quote

Hello,

I am a little embarassed to have to ask this, but I am trying to repair one of a lovely pair of KEF 103.2 which has no bass output. In the first instance I would like to remove the B200 and test the voice coil, then depending on the result of that, examine the crossover. But I can neither remove the bass unit nor the base of the speaker where the crossover lives. What is the trick to this! So far I have only been able to remove the tweeter. Those with smaller hands than I have failed to shift the bass unit by pushing it up from underneath, accessing it via the tweeter opening, even though I have obviously removed the three fixing screws. It still feels very much held in place. I know the crossover is enclosed in the removable bass on the bottom of the speaker but the central retaining screw just turns and turns (I think there is probably a captive nut inside the cabinet which is turning with it) so I can't access the crossover either. And yet the there must be a way. Any suggestions? Thanks.
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speakerguru
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Joined: 18 Nov 2005
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Location: Green Hut, Tovil

PostPosted: Mon Dec 21, 2015 4:29 pm    Post subject: Reply with quote

If you have removed the woofer screws then it must come out by being pushed from the inside. I guess the gasket may have perished into a sticky mess making this difficult. Maybe the person with smaller hands is just not strong enough.

A few suggestions:
1. You could try shock, by dropping the cabinet onto its bottom or onto its front with spacers to allow the woofer to fall out. Start from an inch high and progress with caution.

2. Get a small version of these clamps http://www.ebay.co.uk/itm/2-x-Irwin-Quick-Grip-12-Inch-300mm-Mini-Trigger-G-Clamp-Non-Marking-T5462EL7-/131458797569?hash=item1e9b8e1001:g:SK0AAOSwBahVawmz
They can be reversed to push apart rather than clamp together. You may need to cut the connecting bar to get it in the cabinet through the tweeter hole and you will need your small handed person to align and ratchet it apart.

3. Sustained pressure. Rest the cabinet on its front on small spacers and allow time and gravity to do its work (overnight?).

4. Construct some sort of lever and fulcrum, such that you can apply an outward force to the back of the woofer magnet, through the tweeter hole.

When the woofer is out, re-assess the crossover cover screw removal. Some butchery from the inside may be necessary. You might be able to apply adhesive to secure the threaded insert after drilling access holes from the inside.
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spikeanded
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Joined: 14 Dec 2015
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PostPosted: Mon Dec 21, 2015 10:55 pm    Post subject: Crossover removal Reply with quote

Thanks for that. Tonight I had some success removing the bass unit, using two coathangers as a lever and brace, and as expected, it works. Unfortunately, even after removing the single fixing screw, I could not remove the crossover as it is glued to the base of the speaker, which itself is glued onto the cabinet. I cannot see a way to pry the crossover free without running a risk of damaging it.
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speakerguru
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Joined: 18 Nov 2005
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Location: Green Hut, Tovil

PostPosted: Mon Dec 21, 2015 11:21 pm    Post subject: Reply with quote

Again, it will only be stuck to the cabinet base using double sided adhesive foam pads. They have been stuck there for a long time, so will not budge. Try to get a blade under the crossover and slice through the foam pads. Try not to cut your fingers!
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