Reply to "Bad noise from locomotive when increasing speed, noise stops when decreasing speed - ever heard or seen this before?"

#1 you have the volume maxed to where it is already crackling in the speaker before you do anything.

#2 When you increase throttle- that's actvating dynachuff- dynamic chuffing increase with more bass to the chuff. When back off the throttle, that decreases the chuff to more of a coasting or drift chuff. Less bass = less speaker cone excursion, thus less or no crackle when not in the hard bass acceleration chuff.

I would replace the blown speaker and then also turn down the volume...