In 1969, the British engineer JLH designed this circuit, which can compete with the Thomson tube amplifier at that time with 4 transistors, so the sound is vevy good.

Circuit board materials：

Printed circuit board: 1.6 double-sided gold, gold letters, gold marking, very eye-catching, very high quality.

Finished board, 10CM long, 7.8CM wide, 3.5CM high.

Gold seal tube: small tube 2N2907, medium tube 2N1711, large tube 2N3055 (imported disassembled tube) or imported new ON3055.ON15024

Capacitors: Panasonic FC. Ruby, Taiwan Jiahe, Germany ERO international brand, all new material.

Resistors: floating low temperature metal film resistors, 5 ring precision.

Output power: class A 10 watts, quite ordinary 35 watts or so.

Recommended 100-150 watt transformer, output 12-26V, personally think 18-19 transformer effect is good. With the store with 72,000 UF rectifier filter plate, good sound quality, almost 0 down noise.

Hear the human voice can choose 3-5 inch full-range speaker, hear the bass recommended to choose the caliber in 5-8 inch full-range speaker, you can also choose the power of 120 watts or less, 8 inches or less, the true sensitivity of 86 or more 2 units box, do not see only 10 watts power thrust is good.

The board follows the S-shaped circuit alignment, there is a 1MM gap between the corner aluminum and the circuit board, heat transfer to the board is small, stick to the original circuit.

Current adjustment：

Set the current: the universal meter to 10A DC file, remove the VCC line on the amplifier board, one meter needle to the connector on the board, the other meter needle to the VCC line only removed, adjust the board KT2 can be the resistor, bottom the large inverse small, set to 0.8-1.2A on it.

Package：

One Pair JLH1969 Class A Amplifier Board