Proximity Hum And How To Eliminate It

I finally got rid of the last vestiges of a very faint hum by….moving the cables from phonostage to preamp around. I can’t believe it made this much difference, but the proof is in the pudding. Now I am terrified to move anything for fear of losing the silent background.

Such a black art!

Thanks guys, will give floating the earth a try and contact Thomas to see if he has any suggestions.

A new phono stage is definitely an option.

@alan60 , Inductive hum is very hard to stop. This is one of the reasons toroidal transformers are so popular, they are less prone to doing this. Just for fun, is the power transformer a toroid? 

This may seem counterintuitive but try floating the ground on the unit. Trust me on this, stranger things have happened and it is a cheap thing to do. I have several cheaters in reserve just in case.  Frankly, my best guess is that nothing is going to work except distance. The real choices are distance vs new phonostage. Sucks doesn't it. Expensive vs impossible. Time to get creative.

Beautiful amplifier. Have you contacted the manufacturer? I have a large tube power supply on my tube phono pre and I can only get the pair hum-free by distance and orientation. You could try a grounded (mu?) metal plate. Have you ruled out overly sensitive tubes?

Thomas Mayer D3A.

Thomas Mayer D3A.

What make and model? Try turning them 90 degrees to each other.