Lehle’s Julian Parametric Booster has parametric controls of mids and treble with +/-15dB gain. The Gain, Freq, Boost, and Treble controls allow settings to reproduce familiar sounds, and it has a switch that reduces impedance from 1 meg-ohm to 10 K-ohm. The overdrive of the connected amp can be fine-tuned with the Gain pot ranging from super-clean (thanks to its JFET input stage) to distorted. Incoming current is rectified and doubled. The Julian has two modes when not in use – TB (True Bypass) or TS (True Sound with active buffer). Read more at http://lehle.com.