bdc Posted January 20, 2004 Share Posted January 20, 2004 I bought a pair of Fortes and one of the speakers makes a very awful sound when a loud bass note hits. The sound from the woofer itself seems to be fine, however the passive radiator in the back seems to vibrate 'too much' causing the sound. While comparing that speaker's passive radiator to the other's, I noticed that the radiator moves a lot more than the other one. Also, if I'm only playing music at a relatively low to moderate volume, tilting the entire speaker forward will eliminate the problem, and I'm assuming this is so because the gravity prevents the radiator from moving out as much. Is this a common problem with passive radiators? Do they just wear out? Is there an easy way to fix the problem? Thanks in advance for your help. Sorry if I'm not specific enough or what not, I'm not too familiar with the technical terms of everything. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted January 20, 2004 Share Posted January 20, 2004 bdc, Try taking the PR out and rotating it 180 degrees. You can also inspect the inside spider at the same time. Then report back. Rick Edit: while you are in there make sure nothing is loose inside to rattle like the crossover or a foriegn object. Quote Link to comment Share on other sites More sharing options...
bdc Posted January 20, 2004 Author Share Posted January 20, 2004 Thanks for your help. I'll try it as soon as I get home. I may not be able to reply until tomorrow... the internet at my house has been down for the past week. Again thanks, I'll try what you said and report back, Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 20, 2004 Share Posted January 20, 2004 I'm not sure this is a matter of the bad unit ("A") having a passive radiator moving too much. It could be that it is good and the other one ("B") is the real problem. Before taking anything apart, try the following. With fingers spread, try pushing in the front woofer about 1/8 to 1/4 inch; the back passive should move out. Hold the pressure for about 5 seconds and make sure the passive does not move back to the original position. If it does, there is air leak somewhere. Do this gentle pressure with the two woofers and the two passives on the pair (one at a time). In all cases you should not note any binding or gritty - ness. This is to check for binding. I think the passive does not any close clearances which will cause binding. However, a distorted voice coil on a woofer will cause clearance problems, and bad sounds. You might be able to detect it by the above. Let us know what you find. Gil Quote Link to comment Share on other sites More sharing options...
itsmyforte Posted January 20, 2004 Share Posted January 20, 2004 the passive may not be screwed down tight and its smacking the cabinet very slightly. Quote Link to comment Share on other sites More sharing options...
bdc Posted January 21, 2004 Author Share Posted January 21, 2004 Well, I went home and rotated the PR 180 degrees as you said but it did nothing. The irritating sound is still there and it's not subtle either. Sorry Gil, I wasn't able to see your post as my internet at home is still down. I'll try that today and let you know. Also, when putting the PR back on, one of the screws would not tighten all the way, i.e., it just kept spinning. Could this be a problem as well? Again, thank you all for your help. Quote Link to comment Share on other sites More sharing options...
HeritageBob Posted January 21, 2004 Share Posted January 21, 2004 I had this problem with one of my Forte II's a while back. You may have the same problem as I did. It was a rasping nasty noise coming from the back radiator on bass notes. What it ended up being was that the glue was coming undone on the outside of the Radiator where the spider/ribbing surround was attached to the actual paper woofer. Press around the outside of the passive and see if you can reproduce the raspy like sound with the woofer in or out of the enclosure. It will be the sticky sound of the glue going bad on the surround as you move the woofer. Klipsch sells new radiators and they were like $55 or so for the Forte II. I took mine to a speaker repair shop and they took the old spider surround off and attached a new one with new glue for $30. Works perfectly. Bob Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 21, 2004 Share Posted January 21, 2004 I think the leak test I suggested will pick up a bad surround. One loose screw out of eight shouldn't be a problem. But good practice is to have everything snugged up. The problem is that the relatively flimsey MDF stripped out. The classic solution is to remove the screw. Find one or two flat toothpicks. Put one into the hole and break off the remaining part. You'll probably need to do this two or three times. It is mostly to just fill up the hole. Then screw back in the screw. The toothpicks will give it something to bite on. Gil Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 21, 2004 Share Posted January 21, 2004 So, where are you located? I'm in Chicago and I get to Dallas from time to time. I'd be pleased to help. Gil Quote Link to comment Share on other sites More sharing options...
HeritageBob Posted January 21, 2004 Share Posted January 21, 2004 Mine didnt leak at all. They moved quite well when pushed on by the front "active" woofer, and they also came back to their static position very very slowly. My surrounds weren't bad per se, and the glue was still holding them perfectly. It was just for some reason the glue became "tacky" and made a nasty sound when the passive radiator started to see some good excursion. I dont know how good the glue was that Klipsch originally used, and I also cant explain why only one of my Forte II's of a matched pair ended up doing this, but all it took to hear and reproduce this sound was to press in and out on the passive radiator, or simply press my finger around the areas of the surround on the passive radiator. Its a tacky glue sound which seems harmless, but when the speaker is really roaring it sounded horrid. Quote Link to comment Share on other sites More sharing options...
bdc Posted January 22, 2004 Author Share Posted January 22, 2004 Well I pushed in the woofer and observed the radiator. It was pushed at but after a second or so goes back in a bit (but not to its original positon). Then I tried it on my other Forte, the one that sounds fine, and it did the very same. Is this supposed be this way or is it supposed to stay out and not move in at all? My other Forte sounds fine, as far as I can tell, anyway). Also, I don't think the glue thing is the problem, it's more like a vibrating sound than a rasping. I'm located in Sacramento, CA so I think I'm a bit far. Quote Link to comment Share on other sites More sharing options...
Strabo Posted January 22, 2004 Share Posted January 22, 2004 I'm not totally convinced that it is the PR. Have you tried swaping them between the speakers to see if the problem moves too? It the sound doesn't move then try swapping the woofers and see what happens. Might even be that the crossover came loose and is rattling inside one of the cabinets. It is mounted right below the PR. To answer your question, yes. The PR should move out and hold for a couple of seconds before leaking down when you press on the woofer. But they will probably leak down as the cabinets aren't perfectly sealed. Quote Link to comment Share on other sites More sharing options...
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