Secondhand in box, VOX Big Ben Overdrive The VOX Big Ben Overdrive really captures the quintessential British overdriven amp tone. Built to the highest standard, VOX designers have captured the characteristics that characterize the best of British amp design.The valve-powered Big Ben Overdrive pedal responds intuitively to your playing dynamics, cranking out that extra firepower when you really dig in and want to cut through. The Gain knob varies the overall gain of the pedal from bluesy and mellow to fat and saturated, while the Tone knobs adjusts the overall tonality of the pedal.The bottom end performance is tight and focused while the mid-range punch and sweet top end make the Big Ben a fabulous choice for grinding rock tones and soaring solos.Normally, valves are used at high voltages and this restricts their use in battery-powered devices such as guitar effects pedals. Historically, attempts have been made to use valves at low voltages in what has been dubbed “starvation” mode, but these circuits don’t allow the valve to function in an acceptable manner acting little more than expensive light globes.The tube simply cannot be biased to a satisfactory operating condition. Plus, the necessary heater filament current is too high to deliver acceptable battery life. Imagine how annoying it would be to have to change batteries every ten minutes in the studio or during a gig.With their COOLTRON Technology, VOX have changed everything. The COOLTRON circuit basically operates by using two very special signal paths. The first is the “servo circuit,” which provides the right conditions between the plate of the valve and the grid. This achieves controllable, stable parameters for the valve and provides the correct operating conditions for the valve to function as it would if run at a higher voltage.The second circuit is a patented power supply that provides a low voltage, low current supply to the heater elements in the valve. Since the valve is now running at such a reduced supply level, the anode current is much smaller than normal. This means that the amount of heat required at the cathode to achieve sufficient cathode current emission is much smaller – hence the ability to run the heaters at a lower level and for COOLTRON pedals to run for 16 hours on 4 x AA. No PSU with this item. batteries!