The Darkglass Harmonic Booster is a clean bass preamp that improves the attack of your bass while tweaking the midrange to add a percussive bite.  Originally designed as part of a bass overdrive, the team at Darkglass separated the preamp section after realizing their 'harmonic excitation circuitry' sounded great with less gain.  The Harmonic Booster has an active 3 band EQ along with a character knob to add additional enhancements.