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4 layers106.7 × 81.3 mmInput, the printed circuit board in 3D

An open source audio interface

Size
106.7 × 81.3 mm
Copper layers
4
Thickness
1.6 mm
Parts
155
Nets
119
Pads
486
Tracks, vias
733, 212
Pours
7
Routed
Yes
KiCad
KiCad 10.0 (file 20260206)
Created
8 Apr 2025
Updated
25 Sep 2026

Overview

Input 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 4-layer board of 106.7 × 81.3 mm with 155 parts on 119 nets, routed with 733 tracks and 212 vias.

It is built around the INA1650IPW, OPA1637DGK and OPA1641AID, with the THAT5263 and BAV99 among its other parts. Its parts include 65 resistors, 49 capacitors, 17 connectors, 10 diodes and 9 ICs.

Main components

5

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

155
QtyValueFootprintReferences
27100nFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC1, C2, C3, C13, C14, C15, C16, C17, C18, C19, C20, C28, C30, C32, C33, C34 +11
152kResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR11, R12, R13, R14, R15, R40, R41, R42, R43, R44, R49, R50, R51, R52, R53
810Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR6, R7, R16, R17, R45, R46, R54, R55
810kResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR58, R59, R60, R61, R62, R63, R64, R65
810uFCapacitor_THT:C_Radial_D5.0mm_H11.0mm_P2.00mmC21, C22, C25, C26, C44, C45, C48, C49
8510Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR25, R26, R27, R28, R33, R34, R35, R36
71kResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR1, R2, R3, R30, R31, R38, R39
61k2Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR8, R9, R24, R29, R32, R37
65kResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR18, R19, R47, R48, R56, R57
4VTVS14ASMFDiode_SMD:D_SMFD4, D5, D6, D7
3100Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR20, R21, R23
3330pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC23, C24, C31
3BAV99Package_TO_SOT_SMD:SOT-23D8, D9, D10
3LEDLED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolderD1, D2, D3
3OPA1637Package_SO:VSSOP-8_3x3mm_P0.65mmU3, U8, U9
3OUT_BIASConnector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_VerticalJ5, J12, J13
3SolderJumper_3_Bridged12Jumper:SolderJumper-3_P1.3mm_Bridged12_RoundedPad1.0x1.5mmJP1, JP2, JP3
2100pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC9, C10
21MResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR10, R22
21uFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC27, C29
2220pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC6, C11
222pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC4, C5
247uFCapacitor_THT:C_Radial_D10.0mm_H12.5mm_P5.00mmC7, C8
26k81Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR4, R5
2Conn_01x02_PinConnector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_VerticalJ9, J17
2DG1412EEQPackage_SO:TSSOP-16_4.4x5mm_P0.65mmSW1, SW2
2OPA1612AxDPackage_SO:SOIC-8_3.9x4.9mm_P1.27mmU6, U7
2SW CTRLConnector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_VerticalJ10, J11
11000uFCapacitor_THT:CP_Radial_D8.0mm_P3.50mmC12
1Conn_01x03_PinConnector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_VerticalJ6
1Conn_01x05_PinConnector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_VerticalJ7
1Conn_01x08_PinConnector_PinHeader_2.54mm:PinHeader_1x08_P2.54mm_VerticalJ4
1Conn_01x09_PinConnector_PinHeader_2.54mm:PinHeader_1x09_P2.54mm_VerticalJ8
1INA1650Package_SO:TSSOP-14_4.4x5mm_P0.65mmU4
1NCJ10FI-HConnector_Audio:Jack_XLR-6.35mm_Neutrik_NCJ10FI-H_HorizontalJ2
1NMJ6HHD2Connector_Audio:Jack_6.35mm_Neutrik_NMJ6HHD2_HorizontalJ1
1OPA1641Package_SO:SOIC-8_3.9x4.9mm_P1.27mmU5
1OUT_INSTConnector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_VerticalJ20
1OUT_LINEConnector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_VerticalJ19
1OUT_MICConnector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_VerticalJ18
1PH_ENConnector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_VerticalJ3
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

Questions

How big is the Input PCB?

It measures 106.7 × 81.3 mm and has 4 copper layers, 1.6 mm thick.

What parts does the Input use?

155 parts, built around the INA1650IPW, OPA1637DGK, OPA1641AID 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 Input KiCad files?

From the oliverpaddock/OpenMic repository on GitHub, at the commit this page was made from: the board is hardware/pcb/prototypes/input/v3/v3.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 Input 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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