Symbol 5071 from IEC 60417 - Title/Meaning: Stereophonic Function/description: To identify the ""stereo"" position of a ""stereo/mono"" switch and on equipment to indicate that it is suitable for stereophonic sound.
Additional information: 
Published in: First edition, 1973
Own work using: iso.org/obp/graphics/grs/4d244d71-12cd-4d06-86dc-1081244e47be 200.png
Vectorization:  Mrmw