I bought a Fender Rumble 100 bass amplifier and was curious about the frequency response. I couldn’t find anything online so I measured it myself with REW and a UMIK-1.

Below are normal, vintage, and contour settings with all EQ knobs at the center position. The volume was set low and the mic was place a few feet in front of the amp. The amp was a few inches from a wall to the rear, and a foot from a wall to the right.

Presumably the curves change as volume increases, or if it’s positioned away from walls. I wanted to use the amp as a monitor as well as for bass so I stopped measuring after this.

I plan to return it and try a Tech 21 Power Engine Deuce Deluxe.