Preamp/mixer.
Dev_LOOP is a versatile analog IO board, stereo preamp and mixer designed to interface with various DSP development boards, usually not equipped with a proper hi Z instrumental inputs, analog dry path, input level control and other features typically seen in guitar pedals.
Design goals:
- Mono/stereo operation with versatile IO routing.
- High input impedance: 1MOhm.
- Adjustable input gain: -/+15dB.
- Mixer stage can work as Dry/Wet blender or as typical Effect Level control (for delays etc.).
- Output level control.
- Low impedance outputs.
- Standard 9V DC power requirement.
Typical application:
Input/Output:
- Typical Left/mono input, Left signal is sent to both input channels.
- Separate mono TS jacks for Left and Right input channels.
- Stereo TRS jack carrying both input channels.
- Left and Right output channels summed and available on the Left Out.
- Separate mono TS jacks for Left and Right output channels.
- Stereo TRS jack carrying both output channels.
- Additional test points on the PCB for easy scoping.
- Input/output jack presence "sense" signals available on pin headers.
Construction:
The construction is mostly in SMT, parts are in 0805 size and SOIC14 for the quad opamps. The Pots are ALPHA 11mm stereo PCB mount ones. I have used the stacked Cliff jacks to save the board space.
Design files are available in the github repository:
https://github.com/hexeguitar/Dev_LOOP
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git clone https://github.com/hexeguitar/Dev_LOOP