Fender Rumble 500 Bass Combo The all-new Fender Rumble Series is a mighty leap forward in the evolution of portable bass amps. Re-engineered from the ground up, new Rumble amps are lighter and louder than ever, with even more power and a classic Fender vibe. A newly developed foot-switchable overdrive circuit and versatile three-button voicing palette deliver powerful tones ideal for any gig. Additional upgrades in this amplifier include Eminence drivers and premium HF compression tweeters.