Having Trouble With New Amp HELP!

[BassFreedom]

Well i wouldnt say its new. its a marshall bass 200, 200 watt bass tube amp. its an old one. at first i had no problems with it, then after two days within using it i started to hear this grumble every time i played a note like it was vibrating off something. i have no idea what to do, what to look for or how to fix it

 

[RickenBoogie]

2 questions. What speakers, (and what load, impedance), and how are you setting your eq? Plus, any other information you could include.

 

[BassFreedom]

hmm i dont know what you mean by speakers but the for the eq almost everything is set rigght in the middle except the volume, sensitivity and threshold