Here is my Hi-Fi preamplifier project. In this repository you can find schematics, PCB layouts, CircuitPython code, BoMs, measurements and photos.
Features:
- MDAC volume controller
- 6 way relay based input selector
- High performance design with measurements
- Quality components and modular design
- Completely digitally controlled
- All open source and written in Python
The preamplifier is made up of a number of connected components:
- MDAC attenuator (PCB, code): Controls the volume
- Input selector (PCB, code): Selects the input
- Encoder panel (PCB, code): Holds rotary encoder and LED indicator ring
- Power Supply 5V (PCB): Power supply for digital components.
- Power Supply +/- 15V (PCB): Analog Power supply for MDAC attenuator
- Micro controller board (PCB, code): Holds the Itsy Bitsy M4 Express and other connectors
- RCA panel (PCB): For the RCA sockets and connectors
The PCBs and schematics were created in KiCad and the code that runs on the micro controller is CircuitPython.
Diagrams, CAD files and other information can be found here: enclosure
THD, S/N ratio and power consumption: measurements
See here for a number of different prototypes. All PCBs were made by OSH Park.
