Ref: Silicon Chip Magazine September 2008 The amp module (KC-5470) is powered using an unregulated rail only. This power supply kit is specifically designed to provide a balanced +/- 55VDC supply to power this fantastic amp kit. It has two LEDs, which illuminate when power is present on the rails and the assist in slowly discharging the filter caps when power is switched off. It also provides another +/-15V supply rail for optional powering of a preamplifier. Finally there is a +20V rail to power a speaker protector project (KC5450). Supplied in short form with PCB and all electronic components. Requires a centre tapped transformer with 40V+40V windings for the +/-55V rails and 15V+15V windings for the auxillaries.