Your next mission: code it yourself like they did in the 1970s.

Neat web project, but I've always used audacity for this...

LoL. Mains hum is not 60Hz. Nor 50Hz. Mains hum is caused by magnetostriction, where magnetic core changes volume when magnetic field is applied. It doesn't care about polarity, only about amplitude. There are 2 max amplitudes per wave so the mains hum is 2x50Hz (100Hz) or 2x60Hz (120Hz).

In linear power supply when one of the diodes in full bridge rectifier blows and there is only one half wave of current going through transformer, you will hear this unhealthy low 50Hz or 60Hz noise.

I am making music right now