Chord resonance with high PF

I converted the Mag Amp into a musical instrument. Now it plays a major chord, with some ability to add the 5th up, and at times a 5th lower than 60Hz it would seem.

The self-defeating auto-relay buzzer doesn't drive the vibrations, it resonates with them. Normally, it should directly control the vibrations, but it audibly vibrates with the different harmonics or octave that's being introduced by the modulation stages of the amp..

And, I found some interesting indications presuming heightened circuit efficiency on the PF meter. When all 3 or 4 radiating notes were in close harmony, the power factor reaches the highest reading yet, at 0.96. What's the chance, that i've stumbled onto the sort of reactive tuning that allows that to happen? :)