This is a bare PCB of a tube amplifier. Each channel makes use of a single low noise tube 6N11( or Russia's 6Н23П or US's 6DJ8)at the input and proceeded by a power tube EL34 to accomplish power amplification. Depending on whether the output transformer to have center-tap or not, the board can be connected in either triode, ultra-linear or pentode mode of operation. The schematic is shown below for reference. We provide detailed schematic ( with values and rating) to buyers by EMAIL. The area enclosed in yellow line represents the traces that are included on the board.