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
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:
| 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:
