Buzzing Marshall 1960A cabinet

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PhiloBeddoe

New member
I have a Marshall JCM 900 1960A slant cabinet that just started resonating like crazy when I hit certain notes on the low E string. There is a loud sympathetic kind of buzz/tone that is much louder at the back of the cabinet than the front. It can barely be heard from the front of the cabinet but is very loud in back and if you put your hand on the cabinet itself you can feel extra vibration. It lags the pick attack a little in time.

It is not a problem with the amp because I just had it retubed thinking that was the problem and I also have a straight cabinet that does not do this.

It doesn't really sound like a blown speaker to me, but then again I've never blown a speaker other than in a home stereo.

Any ideas?

Many thanks
 
This problem is as old as the hills. The back of the cabinet isn't as tight as it used to be.
What I used to do is:
1. Go to the hardware store and get some foam weather stripping, the strips of foam with the adheasive back.
2. take off the back of the cabinet.
3. Put the weather stripping everywhere the back meets the cabinet. Don't forget about the post in the middle.
4. put the back back on the cabinet and try it out.
5. If it still does it, sink a screw through the back of the cabinet into the post.
 
Wow thanks, what a great tip. It does indeed have the feel of a mechanical vibration. At first I thought something was contacting the cabinet and rattling like if you left something on your car dashboard.

I'll give it a try and let you know.
 
Tried Farview's suggestion and it works great. Noticed the post was a little loose when I got in there so that may have caused or contributed. Tightened it up and added "Farview's Gasket" all around and on the post, so now not only is the buzz gone, it is weather-tight and thermally efficient.

Thanks a million!
 
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