An easy-to-build preamplifier with tone control, using an all-in-one IC (TDA1524A - see datasheet) 20dB voltage gain, +/-15 dB bass & treble control, channel balance and switchable loudness contour. Supply voltage +15Vdc to +20Vdc (not included) or you may remove the +12V onboard linear regulator and provide an externally-regulated +12Vdc supply voltage. One feature of this kit is that the amplitude, balance and tone circuits are all voltage controlled!