I bought a second hand Rumble 40 (With warranty). And I’ve got this really weird buzzing and I can’t for the life of me figure out what it is! I’ve tried two different cables, and two bass’.
But the problem is still there, it is bass related, as if I put it lower than 5% (with no overdrive) it dissapears. I’ve opened the cab to check but I still can’t figure it out!
I can’t seem to upload the videos or post Imgur links! But its (iJSpOlx and Sm61ttn on Imgur)
Please help me! Thank you!
Could you try plugging it in to an outlet on a different breaker than the one you’re using now? It could be a grounding issue.
*Not an amp expert
Just tried and still no luck, been in two outlets and an extension cable but still getting the same issue 
Welcome to the forum.
I think you need a couple more posts before you can put links in, it’s to stop the bot spammers.
What country are you in? It can make a difference from the grounding aspects.
I tried searching for this on Imgur to post the links for you but couldn’t find anything.
Hello!
That makes sense I’ll try to break it up (imgur. com/ a/ iJSpOlx) without spaces.
I’m in the UK. And I’ve just tilted the amp forward (with the speaker facing at a 45 degree angle, off the back two legs and it stopped). But if I tilt it back it carrys on, any ideas?
Maybe the power plug at the amp itself is loose? Can you insert it firmly??!
I’ve done a little more digging. And I think it may be one of the screws thats holding the speaker (or the connector behind it). I’ve tightened it up all the way, and it rattles. If I loosen it, it seems to be alot better (but still not amazing).
Have you had any issues like this before?
Does it change like that if you move it around to different places in the room? Or is it only when you tilt it? If the former then it might be picking up RF noise in which case you could experiment with different positions. If it’s only when you tilt it then it does sound like something loose!
I tried different rooms! I mentioned in another comment (2 seconds before you did! ha). But the top left screw that holds the speaker in seems to be the culprute. If its rattling and i push the screw, it stops.
I’ve tried tightening it all the way, but still rattles. I’ve loosened it a bit, and its seems to be better (but will not 100%).
Maybe add some sort of rubber washer/fibre washer/grommet to the speaker mounts? Or actually just some simple gasket like washers made from a cereal box (in my experience gaskets should always be made from cereal boxes; it’s just the perfect grade of cardboard! 
)
Haha! I’ll look for something now to use and see what I can find!
Adding the video links for convenience:
You genius, the cardboard is doing the trick for now! Only been around 30 mins, so will need to monitor it. But doing amazing ha
Funny Story for you. My husband just changed the strings to flatwounds. I thought my strings or amp was buzzing. He came in to check it out for me and started laughing. My amp/strings were fine. I was just jamming so loud that my filing cabinet was vibrating! Good luck with you buzzing problem!