Rotel Hifi Amplifier Clone

This excellent performance amplifier is based on the diagram of the

model RA-20 of the ROTEL brand.From this design the power stage was extracted, whose diagram is shown in figure,

based on the simulations, of this circuit, made by the author of the modifications

85W can be reached with a THD<0.1% into a 4Ω load, and approximately 100W, with the same distortion by raising the voltage to +-45V the circuit diagram is attached. Before the regular use of this amplifier it is necessary to adjust the Bias, for which

it is required to connect a 25W incandescent lamp in series with the power supply

to limit the current and avoid eventual damage to both the equipment and the user,

it is also important to zero the audio input either directly /p>

with some low value resistor, the output of the stage should work without any load

at the exit for at least 5 minutes; Once the above parameters are met,

proceed to take the measurement of the voltage drop generated in the resistor R629

(marked in the diagram as TP1) by adjusting preset VR501, until reaching a value

about 4mV, to achieve a quiescent current of about 18mA

(V=I*R, 4mV/.22Ω= 18mA).

This is the best option for hifi stereo. home theaters.

for making at home i have attatched a file in which pcb layout is given.