Breaking in an amp--or breaking it?

Tonight when I turned my Rumble 40* (modular) amp on (my cable already in), there was a big loud squonk. The settings had no sounds although the amp was clicked on after I had set up the cable connection…(and I turn it first off as always as well.) My plugged in guitar emitted no wired sound, either.

I then tried a spare instrument cable. After a few on-off power moments, to see if it would come back via refirbulation, eventually it did. But many of the settings now had a buzz in the background. I moved the plug to a new outlet, as the surge protector it was in was ancient. The proper sounds eventually returned on each channel. At first they were weaker and hissy. So I turned the tone knob on the base way down and that cut the hissing and feedback. It did seem like I could discern my fingers on frets more cleanly, too, for better or worse. My ears may have been fooling me, but I kept thinking or imagining more of a background hum whenever my hand was on strings, especially on certain modular settings. I have had to turn the tone on the Jazz bass all the way down on many settings to eliminate the buzz, and there still are crackles from the amp on some of these when there is nothing played or when the cable shifts a bit. It’s only 10 feet; my room is far smaller, so it’s a tight space.

I recall from headphone audiophiles how they say it took many hours of “seasoning” their cans before they reached their optimal level, as an aside.

What puzzles me is what happened to the amp and or cable or power? I admit I am very new to this and never used any set-up before, by the way.

So, I’m unsure if I blew a speaker, shorted a bad cable, killed off a surge protector, or simply got the amp to cough out whatever two weeks of use had not regurgitated. Did I break it in or simply break it? (I have until the end of the month to return it, an Amazon “like new” deal.) Any hunches?

P.S. A musician friend suggested I may have ruined the DP-fx. I have no idea how to diagnose that, or give first aid. And how can I tell if this is the cause?

*Thanks to all who helped with the manual for Rumble studio 40 (non-LT!)


No idea, @DrJLMurphy.
There are some much more tech-savvy folk here though… maybe @Korrigan or @T_dub could weigh in here?


It’s hard to diagnose amps without an oscilloscope but if you have the option to return it, you should return it rather than rushing out to buy an oscilloscope… unless you want to take up amp repair. :slight_smile:


Thanks, Gio + Korrigan, for your getting back to me. Today I tried it for an hour and reset to factory settings. I reckon (cross fingers given my newbie-ness) that the amp is working as it should. I cannot hear any weirdness, and as I get used to the tone control on the bass vs the amp pre-sets and effects with their various distortion or cleanness, I think it’s ok, after the incident with the squonk. Maybe it just needed time for a deep breath and another go-around?

As I am pretty much a shut-in for the present, I rely on your online advice, and I appreciate it if anyone else has any remote diagnoses. I wonder if Rumbles have some visual method they can reveal their workings digitally? That is, some hidden way to check itself for any fixes or alert we, the users? Cheers!