DIY high power MOSFET amplifier 200W rms into 8 ohms OR 350W rms into 4 ohms.
Here i propose a project of an AB class power amplifier, at its simplest, assembled with common compoments (not very expensive), based on traditional diagrams : a symmetrical differential input stage, a cascode stage driver and a MOSFET output stage.
The printed circuit board is very compact , and is composed of two subsets : the command stage and the output stage. All resistors are 1/4 watt 1 % metal film (except if otherwise stated). Constant current sources of +/- 1 mA are carried out around T5 and T6. The diodes D1 to D6 allow the use of low noise transistors type BC550C and BC560C, the transistors T7 to T10 form the stage driver. The potentiometer P1 allows the adjustment of the quiescient current to 100 mA per output transistor.
The symmetrical power supply is entrusted to a large transformer of 625 VA, 2 * 51 volts + bridge rectifier and 6 reservoir capacitors of 4700 µF, which gives an output voltage of + and - 70 volts per rail. The output power is 200 Wrms under 8 ohms or 350 Wrms under 4 ohms. Distortion is lower than 0,02 %, damping factor is better than 300, signal-noise ratio is 112 db (balanced A at full power), the input sensitivity is 1,2 volts (200 W under 8 ohms).
http://users.swing.be/edwinpaij/ampli_mosfet.htm
