The output power: 40 w 8 ohm and 60 w 4 ohm load. Preamplifier is used in the same 60 v rails as the power amplifier gain blocks can implement two transistors can provide about 20 v RMS output. This provides a very high input overload. List at least the recommended value is C8. 3300μf capacitor or two 2200μf capacitors connected in parallel would be a better choice. Darlington transistor types of alternative has MJ11014 (Q3) and MJ11013 (Q4) or TIP142 (Q3) and TIP147 (Q4). T1 transformer can be also a 24 24 v or 25 25 v type (ie. 48 v or 50 v center tapped). SW1 switch insert low-cut feature when open. In all cases, Darlington transistors are used as the output device is essential that the transistor (Q2) pass in close thermal contact with the sensor output transistors as possible.
R1__________________6K8 1W Resistor
R2,R4_____________470R 1/4W Resistors
R3__________________2K 1/2W Trimmer Cermet
R5,R6_______________4K7 1/2W Resistors
R7________________220R 1/2W Resistor
R8__________________2K2 1/2W Resistor
R9_________________50K 1/2W Trimmer Cermet
R10________________68K 1/4W Resistor
R11,R12______________R47 4W Wirewound Resistors
C1,C2,C4,C5________47μF 63V Electrolytic Capacitors
C3________________100μF 25V Electrolytic Capacitor
C6_________________33pF 63V Ceramic Capacitor
C7_______________1000μF 50V Electrolytic Capacitor
C8_______________2200μF 63V Electrolytic Capacitor (See Notes)
D1_________________LED Any type and color
D2________Diode bridge 200V 6A
Q1,Q2____________BD139 80V 1.5A NPN Transistors
Q3_____________MJ11016 120V 30A NPN Darlington Transistor (See Notes)
Q4_____________MJ11015 120V 30A PNP Darlington Transistor (See Notes)
SW1_______________SPST Mains switch
F1__________________4A Fuse with socket
T1________________220V Primary, 48-50V Secondary 75 to 150VA Mains transformer
PL1_______________Male Mains plug
SPKR______________One or more speakers wired in series or in parallel
Total resulting impedance: 8 or 4 Ohm
Minimum power handling: 75W
