Electro-Harmonix XO Germanium OD Overdrive PedalThe Electro Harmonix XO Germanium OD is one stop shopping for classic 1960's overdrive tones. Juice up your tone with this hand selected germanium transistor circuit, packed with inventive "BIAS" and "VOLTS" controls which alter the current gain and voltage going to the transistor. Go from tight, bright overdrive to slow and sagging dirt with a couple twists and transport yourself back to the '60s in style.