300 Watt MOSFET Real HI-FI Power Amplifier

Amplifier Specification:

• Maximum Output: 240 watts rms into 8 Ohms, 380 watts rms into 4 Ohms
• Audio Frequency Linearity: 20 Hz – 20 kHz (+0, -0.2 dB)
• Closed Loop Gain: 32 dB
• Hum and Noise: -90 dB (input short circuit)
• Output Offset Voltage: Less than 13 mV (input short circuit)
• Phase Linearity: Less than 13° (10 Hz – 20 kHz)
• Harmonic Distortion: Less than 0.007% at rated power
• IM Distortion: Less than .009% at maximum power

The amplifier consists of two completely separate monaural amplifiers each channel has its own power supply, resulting in zero inter-channel cross talk, a common phenomenon in amplifiers sharing the same power supply.

In order to obtain the full output power each supply transformer should be rated at 40VAC – 0 – 40VAC at 640VA. Unlike many designs relying on the reservoir capacitors to supply peak currents, I prefer to have the raw power available from the transformer resulting in much faster transients.

Although the RAS300 specifications are moderate, when listening to it you will immediately experience the massive reserve power available and never have any cause of anxiety that something is going to give in that one would when driving many amplifiers loud.
You will hear nothing but reality with no distortion at any level and I guarantee that this amplifier will divulge the best qualities of any equipment connected to it.

BOM:

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Ref	Qty	Name	Description	Package
R18	4	0E22	Resistor	5 Watt
R19
R21
R25
C1	4	100n	Capacitor Cerm 63V	5.0 mm
C3
C7
C10
R24	1	10E	Resistor	1Watt
R8	1	10K	Resistor	500mW
R9	2	1K0	Resistor	500mW
R10
R14	1	1K2	Resistor	500mW
D1	2	1N4148	DIODE
D2
R1	2	2K2	Resistor	500mW
R23
Q2	2	2SJ162	MOSFET	TO-3P
Q3
Q4	2	2SK1058	MOSFET	TO-3P
Q5
R12	2	3K3	Resistor	500mW
R13
C8	2	4700u	Capacitor Elec Radial 63V HITANO/RUBICON
C9
C5	2	82p		5.0mm
C6
Q9	2	BD139		TO-126
Q10
Q7	2	BD140		TO-126
Q8
F1	2	Fuse 20mm PCB Mount 3- 5Amp Slow Bk
F2
Q11	2	BC556C		TO-92
Q12

PCB:

PCB Layout: