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2 layers66 × 43.8 mmV2-mic, the printed circuit board in 3D

An open source audio interface

Size
66 × 43.8 mm
Copper layers
2
Thickness
1.6 mm
Parts
57
Nets
50
Pads
205
Tracks, vias
259, 193
Pours
1
Routed
Yes
KiCad
KiCad 10.0 (file 20260206)
Created
8 Apr 2025
Updated
25 Sep 2026

Overview

V2-mic 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 of 66 × 43.8 mm with 57 parts on 50 nets, routed with 259 tracks and 193 vias.

It is built around the OPA1637DGK and THAT5263. Its parts include 20 capacitors, 17 resistors, 11 connectors, 5 diodes and 3 ICs.

Main components

2

README

README.md

OpenMic

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.

Block diagram 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

AISLER 

AISLER 

Special Thanks

THAT Corporation

Neutrik

Parts

57
QtyValueFootprintReferences
9100nFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC1, C11, C12, C13, C14, C15, C16, C17, C18
52kResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR9, R10, R11, R12, R13
410Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR4, R5, R14, R15
4VTVS14ASMFDiode_SMD:D_SMFD4, D5, D6, D7
2100pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC7, C8
210uFCapacitor_THT:C_Radial_D5.0mm_H11.0mm_P2.00mmC19, C20
21k2Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR6, R7
2220pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC4, C9
222pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC2, C3
247uFCapacitor_THT:C_Radial_D10.0mm_H12.5mm_P5.00mmC5, C6
25kResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR16, R17
26k81Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR2, R3
2Conn_01x02_PinConnector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_VerticalJ2, J10
11000uFCapacitor_THT:CP_Radial_D8.0mm_P3.50mmC10
11MResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR8
147kResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR1
1Conn_01x03_PinConnector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_VerticalJ3
1Conn_01x05_PinConnector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_VerticalJ4
1Conn_01x06_PinConnector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_VerticalJ7
1Conn_01x08_PinConnector_PinHeader_2.54mm:PinHeader_1x08_P2.54mm_VerticalJ8
1Conn_01x09_PinConnector_PinHeader_2.54mm:PinHeader_1x09_P2.54mm_VerticalJ5
1LEDLED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolderD1
1OPA1637Package_SO:VSSOP-8_3x3mm_P0.65mmU3
1OUT_BIASConnector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_VerticalJ9
1PH_ENConnector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_VerticalJ6
1SolderJumper_3_Bridged12Jumper:SolderJumper-3_P1.3mm_Bridged12_RoundedPad1.0x1.5mmJP1
1THAT1580Package_DFN_QFN:QFN-16-1EP_4x4mm_P0.65mm_EP2.1x2.1mm_ThermalViasU2
1THAT5263Package_DFN_QFN:QFN-24-1EP_5x5mm_P0.65mm_EP3.4x3.4mmU1
1TRSConnector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_VerticalJ1
1XLRConnector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_VerticalJ11

Questions

How big is the V2-mic PCB?

It measures 66 × 43.8 mm and has 2 copper layers, 1.6 mm thick.

What parts does the V2-mic use?

57 parts, built around the OPA1637DGK and THAT5263. 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 V2-mic KiCad files?

From the oliverpaddock/OpenMic repository on GitHub, at the commit this page was made from: the board is hardware/pcb/prototypes/input/v2-mic/v2-mic.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 V2-mic 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).

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