2 layers29.5 × 100 mm Output b, the printed circuit board in 3D

Output b

An audio output module for Eurorack, combining two mono input channels into a stereo output with a panning mixer. The stereo output is suitable to drive headphones or small speakers.

Open in PCBKit

Size: 29.5 × 100 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 62
Nets: 39
Pads: 159
Tracks, vias: 269, 6
Pours: 1
Routed: Yes
KiCad: KiCad 8.0 (file 20240108)
Created: 22 Feb 2025
Updated: 20 Oct 2026

Overview

Output b is an open-source printed circuit board by xdylanm, from the xdylanm/modular-output repository on GitHub, published under the MIT licence. It is a 2-layer board of 29.5 × 100 mm with 62 parts on 39 nets, routed with 269 tracks and 6 vias.

Its parts include 28 resistors, 14 capacitors, 4 diodes, 4 transistors and 2 connectors. It belongs with the audio and music boards of this library.

README

README.md

Output Module

An audio output module for Eurorack, combining two mono input channels into a stereo output with a panning mixer. The stereo output is suitable to drive headphones or small speakers.

Features

Two input channels (A and B) with the second normaled to the first.
Independent input level adjustments for both channels
Stereo panning mixer
Level indicator (red indicates $V_{pp} \gtrapprox 9V$)
Output volume control
LM386 output amplifiers

Parts

Qty	Value	Footprint	References
11	100k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical	R1, R5, R7, R12, R13, R15, R16, R19, R20, R21, R24
8	TestPoint	Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical	TP1, TP2, TP3, TP4, TP5, TP6, TP7, TP8
4	10u	Capacitor_THT:CP_Radial_D4.0mm_P2.00mm	C1, C4, C13, C14
4	22p	Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P2.50mm	C2, C3, C5, C6
3	100k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R6, R14, R22
2	10	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R37, R38
2	100n	Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P5.00mm	C19, C20
2	100n	Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P2.50mm	C15, C16
2	10k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical	R4, R23
2	15k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical	R8, R25
2	1u	Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P2.50mm	C21, C22
2	220k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical	R10, R11
2	2M2	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical	R3, R18
2	2N3904	Package_TO_SOT_THT:TO-92_Inline_Wide	Q2, Q4
2	2N3906	Package_TO_SOT_THT:TO-92_Inline_Wide	Q1, Q3
2	330k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical	R26, R27
2	47k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical	R2, R17
2	D_Schottky	Diode_THT:D_DO-41_SOD81_P7.62mm_Horizontal	D7, D8
1	1N4148	Diode_THT:D_DO-35_SOD27_P2.54mm_Vertical_AnodeUp	D4
1	1N4148	Diode_THT:D_DO-35_SOD27_P7.62mm_Horizontal	D1
1	Conn_02x08_Odd_Even	Connector_IDC:IDC-Header_2x08_P2.54mm_Vertical	J5
1	Conn_02x08_Odd_Even	Custom_PinHeader_P2.54mm:PinHeader_2x08_P2.54mm_Vertical_ThinPad	J8
1	MountingHole	MountingHole:MountingHole_3.2mm_M3_DIN965	H2
1	TL074	Package_DIP:DIP-14_W7.62mm_Socket	U1

Questions

How big is the Output b PCB?

It measures 29.5 × 100 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Output b use?

62 parts. 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 Output b KiCad files?

From the xdylanm/modular-output repository on GitHub, at the commit this page was made from: the board is hardware/output/output_b.kicad_pcb and its schematic hardware/output/output.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Output b 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/xdylanm-modular-output-output-b" title="Output b 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/xdylanm-modular-output-output-b.jpg" alt="Output b" width="1200" height="900">

A picture that opens the board, for a README

[![Output b](https://pcbkit.io/embed/boards/xdylanm-modular-output-output-b.jpg?size=s)](https://pcbkit.io/boards/xdylanm-modular-output-output-b)

Source

Repository: xdylanm/modular-output
Board file: hardware/output/output_b.kicad_pcb
Commit: 0f655ad
Licence: MIT

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