4 layers91.4 × 68.6 mm 4mix, the printed circuit board in 3D

4mix

Modular Synths for Everyone

Size: 91.4 × 68.6 mm
Copper layers: 4
Thickness: 1.6 mm
Parts: 167
Nets: 114
Pads: 530
Tracks, vias: 1,076, 142
Pours: 16
Routed: Yes
KiCad: KiCad 9.0 (file 20241229)
Created: 4 Oct 2024
Updated: 25 Oct 2026

Overview

4mix 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 4-layer board of 91.4 × 68.6 mm with 167 parts on 114 nets, routed with 1,076 tracks and 142 vias.

It is built around the SS14 and SS210. Its parts include 94 resistors, 35 capacitors, 11 ICs and 4 diodes. It belongs with the audio and music boards of this library.

Main components

README

README.md

Bread 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 --help

Python + 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

Project image and full feature overview

Bread Modular

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

167

Qty	Value	Footprint	References
38	56k	Resistor_SMD:R_0402_1005Metric	R2, R11, R14, R15, R16, R17, R18, R21, R22, R23, R24, R25, R29, R30, R31, R32 +22
33	100	Resistor_SMD:R_0402_1005Metric	R10, R12, R13, R27, R28, R40, R42, R43, R45, R46, R47, R48, R53, R55, R56, R58 +17
16	0.1uf	Capacitor_SMD:C_0402_1005Metric	C11, C12, C13, C14, C15, C17, C18, C20, C22, C24, C26, C28, C30, C32, C34, C35
16	50k	BreadModular_Pots:Potentiometer_RV09	RV1, RV2, RV3, RV4, RV5, RV6, RV7, RV8, RV9, RV10, RV11, RV12, RV13, RV14, RV15, RV16
12	47pf	Capacitor_SMD:C_0402_1005Metric	C3, C4, C5, C6, C7, C8, C9, C10, C21, C25, C29, C33
11	MCP6002-xSN	Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.29x3mm	U1, U2, U3, U4, U5, U6, U7, U8, U9, U10, U11
9	1M	Resistor_SMD:R_0402_1005Metric	R1, R6, R7, R19, R20, R38, R51, R64, R77
4	10k	Resistor_SMD:R_0402_1005Metric	R3, R4, R35, R36
4	10uf	Capacitor_SMD:C_0402_1005Metric	C19, C23, C27, C31
4	1k	Resistor_SMD:R_0402_1005Metric	R26, R92, R94, R95
4	Conn_01x05_Pin	BreadModular_MISC:Power_Connector	GND1, GND2, V_SUPPLY1, V_SUPPLY2
3	SS14	Diode_SMD:D_SMA	D1, D2, D3
2	100k	Resistor_SMD:R_0402_1005Metric	R90, R91
2	100pf	Capacitor_SMD:C_0402_1005Metric	C1, C2
2	330	Resistor_SMD:R_0805_2012Metric	R33, R34
2	Conn_01x05_Socket	Connector_PinSocket_2.54mm:PinSocket_1x08_P2.54mm_Vertical	INPUT1, OUTPUT1
1	10	Resistor_SMD:R_0402_1005Metric	R37
1	100uf	Capacitor_SMD:C_1206_3216Metric	C16
1	500k	BreadModular_Pots:Potentiometer_RV09	RV17
1	51k	Resistor_SMD:R_0402_1005Metric	R93
1	SS210	Diode_SMD:D_SMA	D4

Questions

How big is the 4mix PCB?

It measures 91.4 × 68.6 mm and has 4 copper layers, 1.6 mm thick.

What parts does the 4mix use?

167 parts, built around the SS14 and SS210. 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 4mix KiCad files?

From the bread-modular/bread-modular repository on GitHub, at the commit this page was made from: the board is modules/4mix/4mix.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.

Can I use the 4mix 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).

Category and platform

Audio and music

Project files

Show this board on your page

A live frame, for any web page

<iframe src="https://pcbkit.io/embed/boards/bread-modular-bread-modular-4mix" title="4mix in PCBKit" width="100%" height="480" style="border:0;border-radius:12px" allow="fullscreen" loading="lazy"></iframe>

A picture

<img src="https://pcbkit.io/embed/boards/bread-modular-bread-modular-4mix.jpg" alt="4mix" width="1200" height="900">

A picture that opens the board, for a README

[![4mix](https://pcbkit.io/embed/boards/bread-modular-bread-modular-4mix.jpg?size=s)](https://pcbkit.io/boards/bread-modular-bread-modular-4mix)

Source

Repository: bread-modular/bread-modular
Board file: modules/4mix/4mix.kicad_pcb
Commit: b47ff0a
Homepage: breadmodular.com
Licence: MIT

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