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klf 20 rattle


jazzfan

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Hello, new to the forum and looking for advice. I have a pair of klf20s I purchased new in 1997. They have been great until recently when Ive noticed a rattle with lower notes, bass lines, etc.

Ive read much info about this being a cabinet issue with the this model. At first i thought it was a bad woofer in the left speaker then I noticed it with both woofers and in the right speaker as well. Both front and rear panels seem intact and tight. Could this rattle be coming from the bracing inside? Is the repair outlined in this forum a good way to go even if the baffle panels seem tight? Thanks in advance for any guidance.

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It's definitely the back panel loose.  Common problem on KLF and Epic CF series especially. Many threads on here about how to fix it and what to do. There's next to no bracing in the cabinets. I have CF-3's currently and once had KLF-30's of which both had to be redone because of poor glue in the channels of the back panel. If you have a large clamp, you can clamp the sides and the noise will stop. Best to just fix it. 

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Thanks for the reply. Even with the panels seeming tight it would still cause a rattle? Would added extra bracing be a good way to go as well? Ive noticed some posts that would suggest this. Im not afraid to tackle this job,want to be sure and do the research before hand.

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With no sound on, bang on various parts of the front and back panels to see if they are loose. There are 2 versions of the klf30s, my guess is there would be the same for the 20s. The first version had little to no internal bracing, the second does have internal bracing. The foam insulation application is different between the 2 as well. To repair the panels (I recommend doing both front and back panels if you need to do one already), use a heat gun to help loosen the rest of the glue, scrape all of the old glue off, then use liquid nail to reinstall the panel. It takes about a day to do one speaker by yourself, and liquid nail takes 7 days to cure. Good luck

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Another thing I have seen is there is a little dust screen in the back, down in the hole of the magnet. On one of my klf30 woofers, this came loose and during low frequencies, the screen would bounce around and make a rattling noise against the dust cap. 

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My advice would be to take the woofers out and get to where you can see the back panels from the inside.  If they look anything like my CF-3's and KLF-30's did, there will be a shortage of glue along the channels or an over abundance of it in other spots.  I had areas where the nails didn't hit where they were supposed to.  Must have built on a Friday at 4:45pm or Monday at 8:25am. ;)  You can typically tell once you look inside and see what's there.  I thought I had pictures of what I did but guess I didn't post them as there's no shortage of pics on how to brace out there.

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I want to thank everyone for the input. I will start this project this weekend and share the results. Are the dust screens at the back of the woofer easily removed if in fact they have been knocked loose and would this removal compromise the performance? great forum with lots of helpful info. Until the repair is complete I will be limited to the headphone system. Woo audio WA3 with a tube compliment of Western electric 421a and 1959 vintage Mullard 6922s. Music hall 25.2 and for the phones, heavily modified AKG 701s and custom Grados with Ypsilon drivers. All completed by myself here at the house. IMHO, a great system.Thanks again for the guidance everyone.

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So I pulled the woofers to get a good look inside the cabinet. All seemed tight and intact. Upon further inspection I noticed the spider is coming loose from the basket. Unglued in some areas, not all the way around, causing the rattle. Any advice on re gluing the spider to the basket? What adhesive to use? Thanks in advance for the input

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