As far as I can tell, it's the original bag. It doesn't have the original reverb cables, though. I'm not sure if that could affect it somehow.Is the tank in the proper bag? If not, that's your problem. If it is, try stuffing some more padding on top of it...a blanket, pillow, etc. If that cures it you know what to do.
Really? Wow, that would be the cheapest fix of all. I'll give that a shot. Thanks.I experienced the same exact reverb feedback at 5+ levels with my DRRI that you describe. I tried swapping tubes, but that wouldn't get rid of it. Not sure what caused it, but I moved the reverb tank a little in the bag, towards the rear of the cab, and the feedback went away. Hasn't come back since.