Craig John Posted June 10, 2005 Share Posted June 10, 2005 I've had my Forte's since 1987. One of them has recently developed a cabinet vibration. I noticed it intermittently during playback. The other day I was using the LF tones on Avia to calibrate my sub. I was using the LF sweeps and warble tones. Whenever the RF speaker got a signal close to 80 Hz, the entire cabinet would start vibrating loudly. It sounds like one of the panels or one of the internal braces has loosened up and is vibrating against its neighbor. All the speakers are firmly seated in the cabinet, as is the binding post plate. In what is probably a related developement, a 2" section of the vineer has lifted on the front, right edge of the same speaker. I'm sure it's not the vineer vibrating, but it is possible that it lifted because of the vibration. Any thoughts on what to look for or how to fix the vibration would be GREATLY appreciated. Craig Quote Link to comment Share on other sites More sharing options...
michael hurd Posted June 10, 2005 Share Posted June 10, 2005 Pull the drivers out and have a look, it sounds like you have a glue joint that is bad somewhere, but the only way to see it would be to physically open the cabinet. Reglue and you should be good to go. Quote Link to comment Share on other sites More sharing options...
Craig John Posted June 10, 2005 Author Share Posted June 10, 2005 OK, I pulled the PR off the back of the speaker. The front panel interior construction appears to be intact. The tweeter, midrange and woofer speakers are securely fastened with screws to the front panel. (However, I'm suprised to see that the screws are all slightly too long and the points protrude beyond the interior surface). The binding post plate seems secure. There is 3/4" bracing around all the interior joints. It appears that the front panel is securely fastened to the sides. Glue seems to be the only method of attachment of the front panel to the sides. There are no visible screws or staples holding it in place. There is excess glue along the internal bracing, especially at the top and bottom corners. The back panel is different. It appears that the internal bracing was attached to the side walls with staples and then the back wall was dropped onto the braces and attched with glue. There is little excess glue to be seen along the bracing and unlike the front walls, there is none in the corners. Looking on the the outside, there is a slight gap between the black rear panel and the side walls around the entire perimeter of the panel. Interestingly, the gap is slightly larger at the bottom than the top, especially on the bottom left side. The back panel appears to have separated slightly at some point, although there is no visible separation seen on the outside of the cabinet. The "paint-line" is visible inside the rear panel gap as though it was in contact when it was painted, but has now moved slightly apart. Could this be the source of the vibration? Can I just lay a bead of glue into this gap? If I get the glue deep enough into the gap, it will probably fill the void. I don't think I can hurt anything by doing this. What are your thoughts on whether this will dampen the vibration? Also, what kind of glue should I use? I have some Elmer's wood glue, but is there a stronger, "industrial-strength" glue I should use? Does anyone know what the OEM glue is? One final observation: the vibration is still apparant even with the PR removed. Should I try removing the woofer and see what happens? Thanks for your insights. Craig Quote Link to comment Share on other sites More sharing options...
Craig John Posted June 10, 2005 Author Share Posted June 10, 2005 I have pic's of the rear panel gap I spoke about. I tried to attach them, but they wouldn't upload. If anyone wants to see them, pls contact me directly at cjg54@roadfly.org Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted June 11, 2005 Share Posted June 11, 2005 If it were me, I'd try to disassemble the bad joints at the rear panel, clean it all up and reattach. Just squeezing glue in there might dampen the vibration for a while, but glue dries out and you might be in the same spot a year from now, just with more glue to deal with. Is the rear panel screwed or nailed as well as glued? Can you remove it without tearing anything up? You might need to use a block, like a 2x4, insert through a driver opening, and rap slightly with a hammer to finish loosening the glue. Klipsch didn't ever set panels in grooves, maybe just rabbets, so it should pop out. Then use a wood chisel to clean up both the panel and rear panel mounting blocks, insure that the blocks are securly attached to side panels, then reglue and screw the back panel back on. Michael Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted June 11, 2005 Share Posted June 11, 2005 Hey Craig You most likely are on the right track here but I had a similar experience with a Chorus speaker once. My problem turned out to be the woofer itself. One winding off of the back of the voice coil had come loose and when the right tone would be played it would rattle. So if you still have problems you might swap woofers and see what happens. mike Quote Link to comment Share on other sites More sharing options...
Craig John Posted June 11, 2005 Author Share Posted June 11, 2005 Thanks for the suggestions. I am busy all day today, but tonight I will try removing the woofer on the front panel and see if I can get better access to the rear panel. I am hoping I can clean this up by attacking both the inside and outside with glue. (The thought of tearing the back panel off is very intimidating to my limited woodworking skills). What kind of glue should I use? Is there something better than Elmer's Wood Glue for something like this? Thanks again. Craig Quote Link to comment Share on other sites More sharing options...
STL Posted June 13, 2005 Share Posted June 13, 2005 Also check the dust caps on the woofers and PRs. Sometimes they come partially unglued and can make quite a racket at certain frequencies. Quote Link to comment Share on other sites More sharing options...
djk Posted June 14, 2005 Share Posted June 14, 2005 Smack your fist on the back panel right behind the midrange horn. If you hear a noise then remove the midrange and put a block of rubber sponge on the magnet and re-assemble. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted June 14, 2005 Share Posted June 14, 2005 I've had this problem in the past as well. In general, cabinets don't just "let go". If the speaker in question has not just "taken a hit" in some way, it is probably not the cabinet unless it has been a problem all along and you didn't know it. In my case it was a loose woofer. The screws may seem tight but may still allow minor movement that gets excited at certain frequencies. I would try repeating the test after loosening and retightening the woofer and PR mounting screws. A small amount of movement after loosening and then retightening may just be the trick. On the other hand, you may have a blown woofer. I would look in those areas before I would mess with the cabinets. Good luck. Quote Link to comment Share on other sites More sharing options...
Craig John Posted June 14, 2005 Author Share Posted June 14, 2005 Upon further examination, I'm pretty sure I'm dealing with a back-panel de-lamination. Using a high-intensity light, one can see a separation of the entire bottom joint between the back panel and the interior braces. The braces seem intact at their attachments to the side and bottom panels, but there is a gap between the bottom frame and the back panel. It appears that the back panel has shrunk or shifted away from the bottom panel. This separation extends up the left rear side of the cabinet a few inches. This is what I first observed as the gap in the "paint-line" on the back of the speeaker. I'm beginning to think that the best solution is removal, clean-up and re-installation of the rear panel. I have a woodworker/cabinet builder coming over on Thursday evening to look at it and give me advice. I'll let you know what he says. Thanks for all your responses. Craig Quote Link to comment Share on other sites More sharing options...
michael hurd Posted June 14, 2005 Share Posted June 14, 2005 If delamination is the curprit, I would lay the cabinet on it's back, and apply a good bead of wood or regular white glue, and let it wick into the gap. After the glue has set for at least 12 hours, I would apply a latex caulking or a liquid nails type adhesive/sealant. This should fix the problem forever, it would be hard to remove the rear panel in one piece, you would likely destroy it taking it out. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted June 15, 2005 Share Posted June 15, 2005 Well good. Looks like you nailed it down. Good luck locking things back down. Let us know if you corrected the problem. Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted June 15, 2005 Share Posted June 15, 2005 I had some friends who once had a delamination problem. After college when I lived on the small farm, some friends decided they would keep some sheep and a few goats until they discovered, to their chagrin, that they stripped the land as high as the d#mned goats could reach standing and the terrain quickly looked like the moon. Even the kudzu was gone!! Personally I dealt with a few cows... and talk about trouble! I never will understand how they can fit ONE-WAY through a 5 inch square of fence when wanting into a neighbor's soy bean field (a nice way to meet the neighbors at 6am on a cold rainy morning, by the way!) but they won't fit through two sections of removed fencing when you try to get them to go back the other way! Must have been all the soybeans that caused them to balloon up! But now I can certainly enjoy a hamburger, even if it is simply out of spite! Quote Link to comment Share on other sites More sharing options...
Craig John Posted June 15, 2005 Author Share Posted June 15, 2005 Thanks for sharing. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.