juanbastonoeste Posted September 11, 2011 Share Posted September 11, 2011 Hey all, Something abnormal has been happening with my 3300 during my last few gigs. When I cross a certain volume threshold (about the top 10% of my normal stage volume) I hear what sounds like something vibrating or rattling inside the 3300. It's loud enough that it almost sounds like the organ is distorting in a bad way. I'm fairly confident though that it's more of a rattling or harsh vibration than some sort of electronic distortion. I tested it at home today and it happens whether the tube circuit is on or off, and certain frequencies seem to make it more noticeable - percussion in particular makes it quite loud to the point where it really messes up the clarity of the sound. I opened the thing up and couldn't find any loose screws - it sounds like its coming from somewhere in top rotor section of the cabinet. Has anyone experienced similar problems with the 3300? I'm a bit baffled as to how to go about fixing this issue, but it is quite annoying so any thoughts or suggestions would be greatly appreciated. Thanks Link to comment Share on other sites More sharing options...
JMcS Posted September 11, 2011 Share Posted September 11, 2011 I thought I heard a buzz from the control/preamp assembly a few years ago. I bought a roll of felt weather stripping at a hardware store and put a layer of it between the metal frame of the control assembly and the cabinet shelf. I also put a line of it around the inside edges of the middle and bottom panels just in case they buzzed too. Is it possible that something fell down inside the horn and is bouncing around when the volume is high enough? Good Luck. Link to comment Share on other sites More sharing options...
juanbastonoeste Posted September 11, 2011 Author Share Posted September 11, 2011 Yes, it does sound like it could be coming from the control/preamp assembly. I will definitely give that a try and see if it does the trick. Thanks for the tip! Link to comment Share on other sites More sharing options...
JMcS Posted September 11, 2011 Share Posted September 11, 2011 This is the felt I used under the metal chassis: Felt Weatherstripping I used 5/8" wide felt around the inside of the cover panels. The chassis is held in place by 2 nuts and bolts. One is easy to see and the other is under the PC board just to the left of the white connector. I put rubber washers (~1" OD) on the bolts under the chassis. I don't remember if I bought slightly longer bolts to make it easier to get the nuts back on. There are 2 lock washers. You might put something over the hole for the horn. If you drop a washer it could roll over and drop through the hole. I could have used a second strip of felt but I thought the rubber washers would keep pressure against the lock washers and nuts. Link to comment Share on other sites More sharing options...
Jim Alfredson Posted September 11, 2011 Share Posted September 11, 2011 Yeah, that metal screen can vibrate and cause a nasty noise. I used some electrical tape to "isolate" it from the case (basically the same concept as JMcS... adding a physical buffer to soften the vibrations). Keep it greazy! B3tles - Soul Jazz THEO - Prog Rock Link to comment Share on other sites More sharing options...
juanbastonoeste Posted September 29, 2011 Author Share Posted September 29, 2011 Finally got around to trying to make this fix. I applied one layer of the same stripping you used under the metal chassis (toward the front where it could go all the way across without blocking any screws) but hasn't seemed to resolve the problem, and it still definitely sounds like the buzz is coming from the control assembly. I'm thinking of trying to place another layer to cover more surface area, but the other problem is that after applying the stripping, the metal screen won't fit back on! Did you encounter this same issue or am I missing something here? Thanks Link to comment Share on other sites More sharing options...
JMcS Posted September 29, 2011 Share Posted September 29, 2011 I took the screen off as soon as I got it home so I could swap the tube and I've never put it back on. Can you get it to buzz at a volume low enough to have your head near the top? If so, try tubning the horn volume up an down to see if that helps localize it. Also, try pointing the horn away from the control assembly and listening near the horn to see if the buzz is coming from the horn. It is possible something fell in or a fly got in there and didn't make it out and it is bouncing on the diaphragm. Does the buzz come and go as the horn turns or does it seem constant? Also, you might check the mounting of the 15" speaker. There is a wood spacer/brace between the 15" and the horn driver. If the screws holding the 15" down have come loose maybe it is bouncing a little and transferring the vibration to the horn assembly. I went through mine and snugged up all the screws I could reach. I don't think I found any I could turn more than an 1/8th of a turn. Link to comment Share on other sites More sharing options...
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