Audio Research SP-10 bile predecessor classic circuit board: exquisite FR4 single-sided glass fiber board 2MM thick, high-quality PCB board, thick copper foil. Size 226 × 206. Selection of imported fever components assembly, power supply by 6Z4 + 6N6 + 6N2 and other bile rectifier bile sampling bile voltage regulator, all filaments AC power supply, dual monophonic left and right symmetrical design, the first four 6DJ8 or domestic 6N11 tube amplifier.