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Project Notes

#309 Audio Connectors

Notes on miscellaneous audio connectors.



Audio signals can be carried by any kind of connection, but there are some more commonly used standard connectors for audio applications. This project is a collection of notes on some of the connectors I use/have encountered.

For more thorough coverage of the variety of audio connectors, see:

3.5mm Connectors

Commonly used for analog audio.


3.5mm PCB-mount Stereo Socket

Example of a stereo socket with bypass. For this specific socket, pin arrangement is as below:

Pin Description
1 Left
2 Left bypass. Plug inserted: not connected; no plug: connected to LEFT(1)
3 Right bypass. Plug inserted: not connected; no plug: connected to RIGHT(4)
4 Right
5 Common/ground


6.35mm (1/4”) Connectors

Primarily used for instruments, mono and stereo.



Commonly used for analog audio and video.



  • shielded audio
  • professional audio
  • snake - multiple XLR connectors in one bundle

Audio Adapters


  • RCA to 3.5mm plug
  • XLR to RCA
  • adapter packages

Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.