

Openmic
An open source audio interface
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 432
- Nets
- 370
- Pads
- 1,687
- Tracks, vias
- 0, 0
- Routed
- Not yet
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 8 Apr 2025
- Updated
- 25 Sep 2026
Overview
Openmic is an open-source printed circuit board by oliverpaddock, from the oliverpaddock/OpenMic repository on GitHub, published under the CERN-OHL-S-2.0 licence. It is a 2-layer board with 432 parts on 370 nets.
It is built around the 74AHCT125D, INA1650IPW and OPA1637DGK, with the CH224K, OPA1642AID and PTN5150AHXMP among its other parts. Its parts include 186 capacitors, 137 resistors, 49 diodes, 19 ICs and 15 switches.
Main components
1274AHCT125D
SOP-14-40℃~+125℃ 1 4 4.3ns@5V,50pF 4.5V~5.5V 40uA 74AHCT 8mA 8mA Schmitt trigger Tri-State Unidirectional SOP-14 Buffers, Drivers, Receivers, Transceivers ROHSNexperiaBuffer/Driver/TransceiverINA1650IPW
TSSOP-14-40℃~+125℃ 4.5V~36V Multi-channel audio Transceiver TSSOP-14 Audio Interface ICs ROHSTexas InstrumentsAudio AmplifiersOPA1637DGK
VSSOP-8-18V~-1.5V、1.5V~18V -40℃~+125℃ 0.0001% 1 Pair Differential Inputs 1-Channel 950uA Enable/shutdown function、ESD protection VSSOP-8 Audio Amplifiers ROHSTexas InstrumentsAudio AmplifiersCH224K
ESSOP-10-150mil-1mm-40℃~+90℃ 100W 4V~30V 5V、9V、12V、15V、20V Overvoltage Protection、Thermal Protection PD 3.0 Power Receiver Controller ESSOP-10-150mil-1mm USB PD ROHSWCH (Nanjing Qinheng Microelectronics)USB ConvertersOPA1642AID
SOIC-8-18V~-2.25V、2.25V~18V -40℃~+85℃ 0.00005% 1.8mA 2 Pairs Differential Inputs 2-Channel Overvoltage protection SOIC-8 Audio Amplifiers ROHSTexas InstrumentsAudio AmplifiersPTN5150AHXMP
X2-QFN-12(1.6x1.6)-40℃~+85℃ 100uA 15uA 2.7V~5.5V Controller X2-QFN-12(1.6x1.6) USB Converters ROHSNXP SemiconductorsUSB ConvertersSN6505BDBV
SOT-23-6-55℃~+125℃ 1.56mA 160mΩ 16V 1A 2.25V~5.5V SOT-23-6 Transformer Drivers ROHSTexas InstrumentsPower Management - SpecializedTHAT5263
QFN24-5X5-0.65QFN24-5X5-0.65 New Arrivals ROHSTHATUncategorisedTPS2116DRL
SOT-583Operating status indication SOT-583 Power Management - Specialized ROHSTexas InstrumentsPower Distribution SwitchesWS2812B-2020
SMD,2.2x2mm0.6mA 0.84mm 120us 160mcd 200mcd 2kHz 2mm 2mm 300ns 470.4nm 515.6nm 520mcd 5V 622.5nm 800Kbit/s Built-in power-on reset circuit、Built-in power-on reset circuit、Integrated intelligent reverse connection protection function Top-mount SMD,2.2x2mm RGB LEDs(Built-in IC) ROHSWorldsemiRGB LEDs(Built-In IC)BAT54S
SOT-231 Pair Series Connection 1V@100mA 200mA 2uA@25V 30V 600mA SOT-23 Schottky Diodes ROHSMDDSchottky DiodesBAV99
SOT-231 Pair Series Connection 1.25V@150mA 100V 215mA 250mW 4A 4ns 500nA@80V SOT-23 Switching Diodes ROHSNexperiaSwitching Diodes
README
README.mdOpenMic
OpenMic is an open-source, 2-in, 2-out, usb-c audio interface.
About
Why open source?
Open source audio/music hardware is not scarce, but general-purpose open source audio interfaces for musicians are essentially non-existent. OpenMic brings repairability, transparency, and education to an overlooked corner of music hardware.
You own your hardware. All schematics, firmware, and design files are publicly accessible so you can repair it, modify it, and understand it.
What is OpenMic?
If you aren't familiar with audio interfaces like the Focusrite Scarlett 2i2 or the Universal Audio Apollo Twin, they basically take analog audio - from a microphone, a guitar, a synth, etc. - and convert it into digital audio your computer can use in a DAW like Ableton, Logic, or Audacity. They also convert digital audio from your computer back into analog audio that you can hear through speakers or headphones. Interfaces also typically provide some sort of amplification or volume control on the inputs and outputs.
This is exactly what OpenMic does. Two inputs that can take microphone/line/instrument level signals, outputs for your speakers, and a headphone jack. Plus a few other features like phantom power that are listed in more detail in the Features section.
System block diagram
Current Status
OpenMic is currently in the prototyping stage. The circuit has been designed and simulated, and individual systems are being built and tested. View the schematics to see the current circuit design.
Progress will be posted on the OpenMic blog as prototyping continues.
Roadmap
- Initial design and component selection
- Simulation for design verification
- Subsystem prototyping
- Full board design in KiCad
- First full v1 board
- Crowd supply launch
- Production
Features
- 2 combo XLR/TRS inputs (mic/line/inst)
- Balanced TRS stereo line outputs
- TRS headphone output
- 48V phantom power
- Direct monitoring
- Up to 32-bit/96kHz
- USB-C bus powered (1.5A) with external USB-C fallback
- Drives headphones from 32Ω to 600Ω
- Fully open hardware and firmware
Getting Started
If you want to view/edit KiCAD files, make sure to add the part libraries located in /hardware/libs to your project or globally in your KiCAD instance.
Sponsors
Special Thanks
THAT Corporation
Neutrik
Parts
432| Qty | Value | Footprint | References |
|---|---|---|---|
| 83 | 100nF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C10, C101, C105, C107, C108, C109, C110, C111, C112, C113, C114, C122, C123, C126, C132 +67 |
| 34 | WS2812B-2020 | LED_SMD:LED_WS2812B-2020_PLCC4_2.0x2.0mm | D1, D2, D3, D18, D19, D20, D21, D22, D23, D24, D25, D35, D36, D37, D38, D39 +18 |
| 25 | 100nF | Capacitor_SMD:C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | C125, C127, C128, C129, C130, C131, C133, C134, C135, C136, C137, C138, C139, C140, C141, C142 +9 |
| 20 | 10k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2, R6, R7, R30, R31, R34, R35, R43, R65, R66, R67, R68, R78, R79, R113 +4 |
| 16 | 1k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R4, R33, R63, R69, R75, R81, R86, R91, R117, R127, R128, R129, R130, R131, R132, R133 |
| 16 | 47k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R18, R32, R49, R58, R61, R71, R73, R92, R96, R98, R99, R100, R116, R135, R136, R139 |
| 13 | 10uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C151, C157, C158, C159, C160, C161, C162, C164, C165, C167, C177, C178, C198 |
| 12 | 10 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R10, R13, R39, R42, R62, R72, R77, R88, R123, R124, R125, R126 |
| 10 | 22pF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C23, C29, C36, C37, C61, C67, C75, C76, C155, C156 |
| 10 | 2k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R16, R17, R23, R28, R29, R47, R48, R54, R59, R60 |
| 8 | 1k2 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R11, R14, R21, R22, R24, R27, R52, R55 |
| 8 | 47uF | Capacitor_SMD:CP_Elec_6.3x5.4 | C18, C22, C27, C28, C33, C41, C60, C66 |
| 8 | 510 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R19, R20, R25, R26, R50, R51, R56, R57 |
| 7 | 10uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C80, C81, C85, C100, C104, C106, C115 |
| 6 | 100k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R45, R80, R87, R97, R134, R137 |
| 5 | 10k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R104, R106, R108, R120, R122 |
| 5 | 1M | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R5, R12, R15, R36, R101 |
| 5 | DG1413EEQ | Package_SO:TSSOP-16_4.4x5mm_P0.65mm | SW3, SW5, SW6, SW9, SW11 |
| 4 | 100k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R107, R111, R112, R114 |
| 4 | 100pF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C24, C30, C32, C34 |
| 4 | 100uF | Capacitor_SMD:CP_Elec_6.3x5.4 | C2, C11, C12, C13 |
| 4 | 10nF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C102, C103, C120, C121 |
| 4 | 10uF | Capacitor_SMD:CP_Elec_6.3x5.4 | C50, C51, C52, C53 |
| 4 | 220pF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C25, C26, C63, C64 |
| 4 | 6.34k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R64, R70, R74, R76 |
| 4 | 6k81 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R8, R9, R37, R38 |
| 4 | 75 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R138, R140, R141, R142 |
| 4 | BAT54S | Package_TO_SOT_SMD:SOT-23 | D31, D32, D33, D34 |
| 4 | BAV99 | Package_TO_SOT_SMD:SOT-23 | D65, D66, D67, D68 |
| 4 | CSD13380F3 | Package_DFN_QFN:Texas_PicoStar_DFN-3_0.69x0.60mm | Q1, Q2, Q3, Q5 |
| 4 | LED | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D13, D30, D59, D63 |
| 4 | OPA1637 | Package_SO:VSSOP-8_3x3mm_P0.65mm | U3, U9, U12, U13 |
| 4 | RotaryEncoder | openmic:PEC11L | SW1, SW7, SW12, SW13 |
| 4 | SW_Push | Button_Switch_SMD:SW_Push_1P1T_XKB_TS-1187A | SW16, SW17, SW18, SW19 |
| 3 | 1uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C169, C170, C180 |
| 3 | 1uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C82, C98, C99 |
| 3 | 22uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C163, C166, C168 |
| 3 | OPA1612AxD | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U5, U24, U30 |
| 2 | 100 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R41, R121 |
| 2 | 1000uF | Capacitor_SMD:CP_Elec_8x10.5 | C14, C15 |
| 2 | 100nF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C150, C197 |
| 2 | 2.2uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C174, C175 |
| 2 | 2.2uH | Inductor_SMD:L_Wuerth_PMCI-201610 | L1, L2 |
| 2 | 47 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R82, R89 |
| 2 | 470nF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C172, C173 |
| 2 | 5k1 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R85, R90 |
| 2 | DG1411EEQ | Package_SO:TSSOP-16_4.4x5mm_P0.65mm | SW4, SW10 |
| 2 | MBR0580 | Diode_SMD:D_SOD-123 | D64, D69 |
| 2 | NCJ10FI-H-0 | Connector_Audio:Jack_XLR-6.35mm_Neutrik_NCJ10FI-H-0_Horizontal | J3, J4 |
| 2 | THAT1580 | Package_DFN_QFN:QFN-16-1EP_4x4mm_P0.65mm_EP2.1x2.1mm_ThermalVias | U2, U7 |
| 2 | USB_C_Receptacle_USB2.0_16P | Connector_USB:USB_C_Receptacle_HRO_TYPE-C-31-M-12 | J7, J9 |
| 1 | 10nF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C176 |
| 1 | 118k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R103 |
| 1 | 127k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R109 |
| 1 | 12k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R119 |
| 1 | 1uF | Capacitor_SMD:C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | C152 |
| 1 | 220k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R93 |
| 1 | 30 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R102 |
| 1 | 330k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R110 |
| 1 | 392k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R118 |
| 1 | 4.7uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C171 |
| 1 | 4.7uH | Inductor_SMD:L_Wuerth_PMCI-201610 | L3 |
| 1 | 475k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R115 |
| 1 | 475uH | openmic:Wurth Elektronik 760390015 | T1 |
| 1 | 499k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R105 |
| 1 | 600R | Inductor_SMD:L_0402_1005Metric_Pad0.77x0.64mm_HandSolder | FB1 |
| 1 | 74AHCT125 | Package_SO:SOIC-14_3.9x8.7mm_P1.27mm | U16 |
| 1 | BAS316 | Diode_SMD:D_SOD-323 | D61 |
| 1 | CH224K | Package_SO:SSOP-10-1EP_3.9x4.9mm_P1mm_EP2.1x3.3mm | U29 |
| 1 | INA1650 | Package_SO:TSSOP-14_4.4x5mm_P0.65mm | U14 |
| 1 | NMJ6HHD2 | Connector_Audio:Jack_6.35mm_Neutrik_NMJ6HHD2_Horizontal | J8 |
| 1 | NSJ12HC | Connector_Audio:Jack_6.35mm_Neutrik_NSJ12HC_Horizontal | J5 |
| 1 | OPA1622 | Package_SON:Texas_S-PVSON-N10 | U15 |
| 1 | OPA1642 | Package_SO:VSSOP-8_3x3mm_P0.65mm | U6 |
| 1 | PTN5150AHXMP | Package_DFN_QFN:Texas_X2QFN-12_1.6x1.6mm_P0.4mm | U18 |
| 1 | SN6505BDBV | Package_TO_SOT_SMD:SOT-23-6 | U21 |
| 1 | TAC5212 | openmic:TAC5212 | U11 |
| 1 | THAT5263 | Package_DFN_QFN:QFN-24-1EP_5x5mm_P0.65mm_EP3.4x3.4mm | U1 |
| 1 | TKC 7M 24MHz | Crystal:Crystal_SMD_TXC_7M-4Pin_3.2x2.5mm_HandSoldering | Y1 |
| 1 | TPS2116DRL | Package_TO_SOT_SMD:SOT-583-8 | U22 |
The 422 most common of 432 parts.
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Questions
What parts does the Openmic use?
432 parts, built around the 74AHCT125D, INA1650IPW, OPA1637DGK and CH224K. 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 Openmic KiCad files?
From the oliverpaddock/OpenMic repository on GitHub, at the commit this page was made from: the board is hardware/pcb/main-board/openmic.kicad_pcb and its schematic hardware/pcb/main-board/codec.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Openmic design in my own project?
Its repository publishes it under the CERN-OHL-S-2.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).