The OP asks how deadly is transformer hum. With only a little bit of exaggeration, I feel transformer hum might have significantly lowered risks to my life:
I have a class A tube amp. A little bit of transformer noise when up close, but nothing to annoy or out of the ordinary IME. Earlier this year, I moved out of the new-ish apartment building I was living in when I bought the amp into an old house. Now the transformers were humming loudly. I tried new tubes I had in reserve. I tried tightening the transformer mounting bolts. I tried a couple of DC blockers. No improvement. I checked voltage — consistently within a half volt of 123v at different times and at different outlets.
A clue that the house wiring might be an issue came from noticing that the equally-annoying hum from the speakers was reduced after switching off all other circuits (but still no reduction in mechanical transformer hum).
I gave a call to the owner of a local audio shop from whom I had bought speakers and sources. To his credit, he referred me to his electrician, rather than different amps or power treatments. Long story short, the electrician replaced the corroded meter box and exterior wire, the ancient and miswired electrical panel, the grounding rod (with two), all of the outlets and switches (removing a bunch of dimmer switches), and some old interior wiring (where it appeared that high current draw had nearly started a fire). In the course of that, he removed some weird junction boxes in between the meter box and before the electrical panel, fixed phase miswiring and shorts in a few outlets I had not yet used, and redistributed load at the electrical panel.
The result? Not exactly silence, but the same faint mechanical hum as when I bought the amp, and equally low noise at the speakers.
So, despite what you are told by some (@cakyol), mechanical transformer hum is not always because of mechanical issues. An amp that works fine at the factory bench can misbehave when fed AC with loads (literally) of harmonics on the line. I would recommend trying all the nearly-free options I tried above. If you can, I would highly recommend following @jea48’s advice to see how your amp behaves connected to a couple of different mains power sources. (A techie’s would be ideal if you don’t mind paying the inspection fee, but a friend’s in a newer house in a different neighborhood would also be useful.)
How did the hum improve my odds of survival? About a week after the electrical work was done, we had several nights of intense thunderstorms and strike lightening. I sure felt more secure knowing that I had new grounding rods and a whole-house surge protector, and that several wiring faults had been rectified — which I probably would not have had done were it not for going all out to fix the transformer hum.
Best of luck in your quest for (good) silence.
I have a class A tube amp. A little bit of transformer noise when up close, but nothing to annoy or out of the ordinary IME. Earlier this year, I moved out of the new-ish apartment building I was living in when I bought the amp into an old house. Now the transformers were humming loudly. I tried new tubes I had in reserve. I tried tightening the transformer mounting bolts. I tried a couple of DC blockers. No improvement. I checked voltage — consistently within a half volt of 123v at different times and at different outlets.
A clue that the house wiring might be an issue came from noticing that the equally-annoying hum from the speakers was reduced after switching off all other circuits (but still no reduction in mechanical transformer hum).
I gave a call to the owner of a local audio shop from whom I had bought speakers and sources. To his credit, he referred me to his electrician, rather than different amps or power treatments. Long story short, the electrician replaced the corroded meter box and exterior wire, the ancient and miswired electrical panel, the grounding rod (with two), all of the outlets and switches (removing a bunch of dimmer switches), and some old interior wiring (where it appeared that high current draw had nearly started a fire). In the course of that, he removed some weird junction boxes in between the meter box and before the electrical panel, fixed phase miswiring and shorts in a few outlets I had not yet used, and redistributed load at the electrical panel.
The result? Not exactly silence, but the same faint mechanical hum as when I bought the amp, and equally low noise at the speakers.
So, despite what you are told by some (@cakyol), mechanical transformer hum is not always because of mechanical issues. An amp that works fine at the factory bench can misbehave when fed AC with loads (literally) of harmonics on the line. I would recommend trying all the nearly-free options I tried above. If you can, I would highly recommend following @jea48’s advice to see how your amp behaves connected to a couple of different mains power sources. (A techie’s would be ideal if you don’t mind paying the inspection fee, but a friend’s in a newer house in a different neighborhood would also be useful.)
How did the hum improve my odds of survival? About a week after the electrical work was done, we had several nights of intense thunderstorms and strike lightening. I sure felt more secure knowing that I had new grounding rods and a whole-house surge protector, and that several wiring faults had been rectified — which I probably would not have had done were it not for going all out to fix the transformer hum.
Best of luck in your quest for (good) silence.