2 layers223.5 × 160 mm
2 layers61 × 68.6 mm
Modular Synths for Everyone
- Size
- 61 × 68.6 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 38
- Nets
- 27
- Pads
- 139
- Tracks, vias
- 333, 36
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 4 Oct 2024
- Updated
- 25 Oct 2026
Overview
4 mix is an open-source printed circuit board by bread-modular, from the bread-modular/bread-modular repository on GitHub, published under the MIT licence. It is a 2-layer board of 61 × 68.6 mm with 38 parts on 27 nets, routed with 333 tracks and 36 vias.
It is built around the MCP6002-I/P. Its parts include 16 resistors, 9 capacitors and 3 ICs. It belongs with the audio and music boards of this library.
Main components
1README
README.mdBread Modular
An open-source hardware modular synthesizer format designed to be minimalistic and cost-effective: USB-powered, breadboard-friendly, with analog/digital modules and MIDI alongside CV & Gate.
Find your starting point
- Build or explore: modules, specification, common parts.
- Set up KiCad libraries: workspace/library setup. Projects
use the shared
opt/fp-lib-table; initialization copies local submodules rather than cloning them. - Check/export/source parts: KiCad toolkit.
Canonical tools, JLCPCB utilities and skills live under
opt/kicad-tools/.
KiCad quick start
python3 -B opt/kicad-tools/kicad_tools.py --help
python3 -B opt/kicad-tools/kicad_tools.py doctor
python3 -B opt/kicad-tools/kicad_tools.py export --helpPython + installed KiCad CLI; no extra packages for core tools. Private checks,
Gerber/BOM/CPL export, native netlist helpers and read-only sourcing have
distinct requirements and safety boundaries.
Exports are not electrical/release/order approval; keep frozen module scripts
and production designs untouched. Historical opt/kicad-jlcpcb and
.agents/skills/{kicad-workflow,jlcpcb-assembly} resolve through
relative compatibility symlinks.
Agents: start with the KiCad workflow skill or assembly skill, then actual CLI help.
Project references
Module catalog · Modular MIDI · PCB assembly
- Standalone exporter / native part-number setup
- Sourcing, audits and passive planning
- 32bit-5v sourcing / release HOLD
- 16bit-5v sourcing HOLD evidence
Project image and full feature overview
- Modular design: Just like Eurorack.
- USB-powered: It can be portable.
- Minimal design: Cost-effective.
- Modular MIDI support: Communicate between modules; CV & Gate still supported.
- Analog and digital signal paths: It’s your choice.
- Diverse built-in modules: A wide range of pre-designed modules.
- Configurable digital modules: Voice and CV using AtTiny 1616 or ESP32.
- Fully open source: Schematics, PCB designs and code.
- Ease of customization: Create modules tailored to your needs.
- No case required: Use directly on a breadboard or a simple base module.
Parts
38| Qty | Value | Footprint | References |
|---|---|---|---|
| 11 | 100k | Resistor_SMD:R_0402_1005Metric | R3, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14 |
| 8 | 0.1uf | Capacitor_SMD:C_0402_1005Metric | C1, C3, C4, C5, C6, C7, C8, C9 |
| 4 | 1k | Resistor_SMD:R_0402_1005Metric | R1, R2, R4, R15 |
| 4 | 50k | BreadModular_Pots:Potentiometer_RV09 | 1, 2, 3, 4 |
| 4 | Conn_01x05_Pin | Connector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_Vertical | 5V1, 5V2, GND1, GND2 |
| 3 | MCP6002 | Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.29x3mm | U1, U2, U3 |
| 2 | Conn_01x05_Socket | Connector_PinSocket_2.54mm:PinSocket_1x05_P2.54mm_Vertical | INPUT, OUTPUT |
| 1 | 0.01uf | Capacitor_SMD:C_0402_1005Metric | C2 |
| 1 | 51k | Resistor_SMD:R_0402_1005Metric | R16 |
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Questions
How big is the 4 mix PCB?
It measures 61 × 68.6 mm and has 2 copper layers, 1.6 mm thick.
What parts does the 4 mix use?
38 parts, built around the MCP6002-I/P. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the 4 mix KiCad files?
From the bread-modular/bread-modular repository on GitHub, at the commit this page was made from: the board is modules/_deprecated/4_mix/4_mix.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the 4 mix design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).