Symbol 5037 from IEC 60417 - Title/Meaning: Treble control Function/description: To identify the control for the higher audio frequencies.
Additional information: 
Published in: First edition, 1973
Own work using: iso.org/obp/graphics/grs/b284632f-fe5a-4019-b8fa-dcc2fb972956 200.png
Vectorization:  Mrmw