KT88 SE UL tube power amp - underside

The underside of a KT88 SE UL power amp consists of, Edcor XSE series OPT, Hammond 10H choke, rectifier unit with SF diodes and 200uF of filtering. Turret boards were used for the KT88 sockets (ceramic), cathode resistors and bypass caps. All other components are wired, point-to-point, on a smaller circuit board X2 caps are used for the coupling caps. All component are inexpensive and readily available. The amp suffered from hum until the filter caps were increased. 100uF before and after the choke are required. The PS delivers a very quiet 410V. 30V is dropped across the cathode resistors which provide the biasing to the power tubes. At idle 63mA is drawn per tube. The sound is extended and detailed with a 6W delivery. Excellent sound stage depth. Frequency range is from 35Hz to 46kHz (-3dB points).

The amplifier follows the Single-Ended (SE) KT88 Tube Amplifier Schematic by Mikael Abdellah.