AudioAmp380
Design
- Pre-amp plus power amp
- 50 Ohm input impedance
- External mount gain potentiometer
- Gain potentiometer on preamp
- NE5534 Pre-amplifier
- Low-Noise Operational Amplifiers
- Equivalent Input Noise Voltage 3.5 nV/√Hz Typ
- Unity-Gain Bandwidth 10 MHz Typ
- Common-Mode Rejection Ratio 100 dB Typ
- Wide Supply-Voltage Range ±3 V to ±20 V
- Used as single supply
- LM380 2.5W Audio Power Amplifier
- Wide Supply Voltage Range: 10V-22V
- Low Quiescent Power Drain: 0.13W (VS= 18V)
- Voltage Gain Fixed at 50 (34 dB)
- High Peak Current Capability: 1.3A
- Input Referenced to GND
- High Input Impedance: 150kΩ
- Low Distortion
- Quiescent Output Voltage is at One-Half of the Supply Voltage
- 12V nominal
- 10-22V
- Fits into 80x50x20mm extruded aluminum enclosure
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Controls
- RV1 - trade-off book gain/bandwidth - Tune for best sound
- RV2 - volume control (after preamp and before LM380 Amp. 1x5 header wired to external pot
- J1 - Audio In, 50 Ohms input impedance
- J2 - Audio Out, 8 Ohm speakers
- J3 - Power, 10V-22VDC
Rev 2 Schematic
Rev 1 Rework
- Issues
- Front end opamp has + and - reversed
- Also hooked up the feedback to the wrong input
- Replace R1 with jumper
- Replace C9 with jumper
- Remove C2
- 5 Cuts
- 4 on front
- 1 on back
- 5 jumper segments on back
- 2 nodes
Videos
