43W Working Class A Amplifier

Specifications: all specs arw with 5-10% margin of error because I'm constantly changing thing readjusting it but this is what you'll get. - Input sensitivity - 447mV - Input impedance - 33Kohm - Output impedance - 8ohm - Voltage gain - 55 - Current gain - 4125 - Frequency response - flat 20Hz-100Khz - Quiescent current - 3.78A - Output power - 43W@8ohm RMS. - Power Draw - 269W - Efficiency - 16% :/ Resistors - All resistors higher than 100mohm can be 1/2W except the 2 1.3k resistors and the 2k resistor. They should be 2W. All 100mOhm resistors should be hand wound and rated above 50W. Capacitors - keep an eye on the voltages around the capacitors add 15-20% and that's your value. The filtering capacitors should be at least 83V and the decoupling capacitor at least 63V. Transistors - ahh finaly the transistors. As im improvising on the go i suggest you try other variations see how they work. But let's try. Ok WITHOUT any input signal just take a look at the transistor currents. All low power transistors below 150mA should be bc550 or whatever low power transistor you have in spare. All transistors above 150mA should be either 2N3055 (if they're NPN) or MJ2955 (for the PNP's) ⚠ All power transistors (the ones above 200mA) dissipate more than 50-60W each so without sufficient heatsinkinking capabilities don't even attempt this. As it is with all class A amps you better be prepared to dissipate all the heat losses safely.

published 11 years ago