Fender says:

It’s tough to add overdrive to acoustic guitars—not only can it sound un-musical, it can also cause tone-destroying feedback. Designed specifically for use with acoustic instruments, the all-analog Smolder® Acoustic Overdrive elegantly solves these issues with Fender know-how. To soften the bright attack of a piezo pickup we included a Pickup Compensation control that smooths out the highs. The Drive knob controls the amount of distortion, while 3-band EQ and Filter controls let you shape your sound to taste. We even included cabinet simulation to add some flavor when plugged into a full-range acoustic amp or PA.

Designed by our in-house team of experts, the Smolder® Acoustic Overdrive is an all-original Fender circuit. The chassis is crafted from lightweight, durable anodized aluminum, and the Amp Jewel LED gives your pedalboard the classic Fender look. The switchable LED-backlit knobs show your control settings on a dark stage at a glance.