Assembling a BTL Hi-Fi Amplifier with LM1875

The pre-stage uses a high-quality 10x amplifier with the core of the op amp NE5532 to match the input sensitivity of the LM1875
. The preamplifier power supply is best to use a high-speed active servo circuit. High-quality IC must be equipped with high-quality peripheral components, such as
CBB capacitors or tantalum electrolytic capacitors for coupling capacitors; ELNA capacitors for feedback capacitors; and 2×lOOOOr.JLF "black gold" for filter capacitors.
"Just" (each channel) connect 0.22tj:F CBB capacitor in parallel; the resistor uses five-color ring metal film resistor, etc.
It is best for the transformer to adopt "Huan Niu" with secondary AC voltage of 2X18V.
    When the whole machine is installed and debugged, if the circuit has self-excitation, the capacitor value in the phase-shifting network circuit should be carefully adjusted. Generally, the static
voltage should be 0mA ~ 80mA. If the requirements are not too high, the phase-shifting network can also be cancelled. The circuit of one channel is shown in Figure 5-19, and
the circuit of the other channel is exactly the same.