Current negative feedback DC power amplifier

9. The circuit of this power amplifier is relatively simple, but its special feature is that its input stage is not a traditional differential circuit, but a new type of current
negative feedback circuit. Its advantages include wide frequency band, high conversion rate, no phase difference, etc. The Japanese Golden Throat amplifier
worth tens of thousands of dollars also uses this kind of circuit.
    During design, the input stage static voltage is set at
about 1. SmA, and the cheaper A992/C1845 is used.
A872/C1775 can also be used for the second stage, A1145/
C2705, or A1360/C3423.
D669/B649 is used for the push stage, and C5171/A1930 is better.
B649 is used for the bias tube, which is the two adjustable
resistors All use multi-turn precision adjustable resistors. The two Sw resistors at the output end
use metallized ceramic resistors, the other resistors
use 1/4W five-color ring metal film resistors, the 470VF capacitor
uses ELNA, the 0.1VF capacitor uses WIMA, and the 10VF capacitor
uses Sanyo OS-CON solid capacitors. The two diodes in the circuit
can improve the sound quality at large dynamics, which is simple
but effective. The power transformer should be a 200W toroidal transformer
, and the dual 36 Vb bridge stack should be 20A or above.
It is recommended that the filter capacitor be El.NA.PHILPS, Rubycon
and other famous brand capacitors. The impact on the sound quality is very obvious.