tube Amplifier board 50W R transformer 170V+6.3V tube preamplifier power supply for 6n1/6N2/6N3/6N4/6N8P/12AX7/12AT7/AU7 tube tube Amplifier board 50W R transformer 170V+6.3V tube preamplifier power supply for 6n1/6N2/6N3/6N4/6N8P/12AX7/12AT7/AU7 tube. Sale price : $24.00 Category : Consumer Electronics