For a while now I've had this buzzing noise on my little Bugera tube combo. It only sounds when playing some notes, not others. It doesn't sound like a typical electronic buzz, it's jangly and sounds like marbles bouncing on each other. The sound is coming from the back of the amplifier, not the speaker. It sounds like something is loose and shaking. Could this be possible? If so, what should I look for when I go to fix the problem?
"Balance not just for karate, balance for whole life."
Maybe some cables that were supposed to be stuck on something are now too much loose and due to the fact of the frequency of some notes like F ( I don't know which notes are you talking about) the cables vibrate and hit the wall of the back of you amp or it could be something else ...! hope I helped
do you have 2 guitars? if so try another guitar to see if its infact your amp or the guitar itself.

If its the amp, pop the back off and check the connections, 1 or more might need a re-solder job, quick and easy....if thats doesnt do it possibly a tube is going, so take it in for a check up

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