[78-L] Interesting Columbia Viva-Tonal

[Ken Matheson]

   I have found it before in 78's. I don't think it was a problem with crank phonographs.
But with modern playback equipment with good fidelity you can hear it. If you have the equipment or software you can notch it out. If in a US recording 60 cycles could be caused by a poor ground, on mike etc. 120 cycles, bad filtering in a power supply. 180 could be in a power feed in a large building.
Ken