Assembled and tested amplifier module in class A - JLH1969 on a modern element base. Despite the simple design and minimum components, this amplifier is still in the “top” of solutions for high-quality sound and will remain there until the transistor is replaced by a fundamentally new and higher-quality device.
This amplifier has excellent and crystal clear sound quality. Many people compare it to tube amplifiers, however, the bass of the JLH1969 is significantly better. A prerequisite is the presence of a massive radiator with passive cooling (at least 1,500 sq. Cm.), Which can be reduced if forced airflow is used.
Setting up the amplifier is very simple and boils down to:
setting the quiescent current (recommended about 1.2A) using a multi-speed potentiometer“KT-2”, while remembering to shorten the input;
setting the output voltage (to the output capacitor) equal to half the supply voltage using a multi-speed potentiometer “KT-1”..
Supply voltage --- 12V ... 35V
Output power --- 10 ... 15W
Quiescent current --- 0.3 ... 1.8A. (recommended 1.2A)