Hi all. I'm planning on replacing the KEF woofers' donuts which have shown signs of cracking because of age. There are many ways to get the necessary repair kits online, including eBay, of course. However, I have no idea which is the best for the KEF - I've noticed that some of these donuts have been reported as stiffer than others, and I believe this will affect the woofers' performance. Would appreciate advices. Thanks.
Hi.
By coincidence, I did mine a few weeks ago.
I bought my new donuts from www.speakerrepairshop.com. They came with recommended glue (which saves you worrying about glue types). Speaker Repair Shop have been specialising in repair parts for some time, so I suspect that they are carefully selected.
My top tip: Don't try and use solvent like Isopropyl alcohol to clear the old glue off. It doesn't do a great job and takes ages. I attempted it in two sessions and found that the glue was even harder the second time. I ended up damaging a paper cone slightly by tearing off little bits with the glue. I then got out a hot air gun and used it on the lower setting. Avoid pointing the air into the voice coil! A couple of seconds of hot air on a two inch section and the glue scrapes off very nicely with a convex curved scalpel. It only took 10 mins per driver. The first attempt with isopropyl alcohol took 2 hours.
Second top tip: The contact board with the spade terminals is held to the driver basket with rivets that had nearly all failed. It is worth redoing these with fresh rivets regardless.
Check that the gromets are still flexible, and replace if not.
The bass is a lot more present now, and I have the confidence that the voice coil is more supported.
I swapped out all the caps with a Falcon Acoustics kit for good measure and future proofing. No significant change.
I've got some new ferro fluid that I will use to refill the tweeters having cleaned them out - when I have some spare time.
Third top tip: The access hatches were very hard to remove, and I have seen people destroying them during the process. After removing all the screw bolts, I screwed two large (10cm) coach bolts slightly into the chipboard hatches (enough to bind, but not enough to damage or widen the holes greatly). I then pulled on both bolts at the same time. Still not easy, but successful, and no damage was caused.
Last tip: It is easier to unsolder the contacts from the bottom driver, rather than take the leads off the XO board, as they are sealed where they pass through the chamber divider.
Good luck.
By coincidence, I did mine a few weeks ago.
I bought my new donuts from www.speakerrepairshop.com. They came with recommended glue (which saves you worrying about glue types). Speaker Repair Shop have been specialising in repair parts for some time, so I suspect that they are carefully selected.
My top tip: Don't try and use solvent like Isopropyl alcohol to clear the old glue off. It doesn't do a great job and takes ages. I attempted it in two sessions and found that the glue was even harder the second time. I ended up damaging a paper cone slightly by tearing off little bits with the glue. I then got out a hot air gun and used it on the lower setting. Avoid pointing the air into the voice coil! A couple of seconds of hot air on a two inch section and the glue scrapes off very nicely with a convex curved scalpel. It only took 10 mins per driver. The first attempt with isopropyl alcohol took 2 hours.
Second top tip: The contact board with the spade terminals is held to the driver basket with rivets that had nearly all failed. It is worth redoing these with fresh rivets regardless.
Check that the gromets are still flexible, and replace if not.
The bass is a lot more present now, and I have the confidence that the voice coil is more supported.
I swapped out all the caps with a Falcon Acoustics kit for good measure and future proofing. No significant change.
I've got some new ferro fluid that I will use to refill the tweeters having cleaned them out - when I have some spare time.
Third top tip: The access hatches were very hard to remove, and I have seen people destroying them during the process. After removing all the screw bolts, I screwed two large (10cm) coach bolts slightly into the chipboard hatches (enough to bind, but not enough to damage or widen the holes greatly). I then pulled on both bolts at the same time. Still not easy, but successful, and no damage was caused.
Last tip: It is easier to unsolder the contacts from the bottom driver, rather than take the leads off the XO board, as they are sealed where they pass through the chamber divider.
Good luck.
One last thing: Don't forget to remove all the old foam that will inevitably have fallen into the voice coil gap. Shake upside down. Suck out with hoover. loosen with blown air?
Thanks, dublin78, for the very detailed information. I believe that, had a video of your project been made, it would be highly welcome by many upcoming DIYers. Meanwhile, I'll check with "speakerrepairshop" to see how much they ship to Canada. BTW, how many bottles of glue you have used for the whole repair project?