Installation using Bel Canto TA-1500 fever amplifier circuit board

(Only the R channel is drawn in the picture, and the labels are according to the original printed board) o
    Figure (a) shows the pre-tone circuit. This circuit is a common RC negative feedback operational amplifier circuit. The microphone signal is amplified by VTz
and then fed into the ici negative input terminal by VR3. After being mixed with the main signal, it is output by pin 1C1. PR1 and PR3 respectively control
the volume of the main signal and microphone signal to adapt to different signal sources. The tone network is also a common negative feedback type, with high, medium and bass
adjusted separately. The principle will not be described again. Figure (b) shows the composition of IC
3 and the equalization network     in the independent phono input pre-circuit .     Figure (c) is the final power amplifier circuit if necessary during actual installation . This is a typical new Class A dynamic bias fully symmetrical amplifier circuit. This is an audiophile- level final amplifier. As long as the components are properly selected and the installation and debugging are correct, the sound quality will be quite satisfactory. VT4.VT6, a fully symmetrical mirror complementary differential amplifier circuit composed of VT8 and VT10, has extremely high common mode rejection ratio and large dynamic range. VT12.VT14 are cleverly connected across the two output ends of the differential circuit to further improve In order to improve the signal-to-noise ratio and dynamic range of the circuit, oVT18.VT20 constitutes a fully symmetrical voltage push stage. The power output is completed by VT22 and VT26. RP8.VT16 and VT24 form a synchronous bias circuit, which uses its extremely low output resistance to make the base AC voltage drop of the driving stage VT18 and VT20 close to zero; 'PR8 is used to adjust the Vce of VT24 , to control the static current of the final stage so that the final stage works in a dynamic Class A state. VT24, VT22 and VT26 are installed on the same radiator for temperature tracking compensation 6. Adjusting VR7 can keep the midpoint of the whole circuit at zero potential to adapt to the discreteness of the transistor and the power supply fluctuation.