The audio linear amplifier circuit of Japanese HDAM has excellent sound quality, with outstanding low frequencies, full mid tones, delicate high frequencies, comfortable listening experience, and a taste of electronic tubes, which cannot be compared to the preamplifier. Unfortunately, the K170 core tube was discontinued in the later stage, and using K246K30 cannot restore its beautiful sound quality.
This year in 2024, Toshiba original replacement tubes with identical characteristics to K170 were ordered from overseas. The patch contains 2 pieces of 2SK tubes with the same characteristics, which eliminates the trouble of pairing and reduces distortion indicators. The output is driven by 2 pairs of Toshiba 2SC52002SA1943 drivers. The maximum current height is 15A, which is much better than digital amplifiers and LM3886. The circuit has perfect over temperature, output overvoltage, and delay protection
The materials are also in place, including original transistors, German WIMA capacitors, copper pin 1% precision resistors, Japanese Omron relays, etc The PCB is double-sided gold-plated!
PCB size: 184x122mm
Supply voltage: AC18X2 to AC28X2
Output power: 70W/8 ohms, 100W/4 ohms
Frequency band: 10-40KHz
Maximum capacitor installation position: 35MM
Debugging: It's very simple. After welding is correct, turn on the power and adjust the adjustable resistor to make the voltage at both ends of the TEST point 20-40MV. The corresponding static current is 100-300MA. The left turn current is small, and the right turn current is large.
