](https://www.youtube.com/watch?v=3DdUvoc7tJ4)
The video explains how a single needle can play stereo sound, but in doing so explains how the basic idea works before going into the incredible design to do two channels.
](https://www.youtube.com/watch?v=3DdUvoc7tJ4)
The video explains how a single needle can play stereo sound, but in doing so explains how the basic idea works before going into the incredible design to do two channels.