I have a tube/valve headphone amp with a separate power and amplification unit. I do love the amp, but if I place the two parts too close together, there is an audible hum in the background.
These units are of course attached with what appears to be a short proprietary umbilical cable. The obvious answer would be keep them apart, but the cable is too short to not induce stresses and have no noise.
I tried a ferrite choke as I had some on hand. No joy.
Any thoughts? Needing to move them back and forth based on if I’m going to use it, is not ideal.
Have you tried running a ground wire from each piece to an earth ground? Tubes hum. Unfortunately. I had a Woo tube headphone amp that I sold because I couldn’t get the hum out. If you get it sorted please come back and share the solution.
I am using a Woo. The only way I can get it to stop, so far, is to move the pieces apart.
Line conditioner, chokes etc.
They have to be separated. Then, no hum.
Not in the same league as a Woo, but I had a Little Dot that I gave up listening to because of hum. Only on the headphone circuit, but not when using it as a pre-amp.
So, in my case and maybe yours, I am blaming a bad solder somewhere.
Doesn’t sound like any sort of grounding or loose solder joint problem, but rather like a mains transformer with too large a stray field.
It either needs a Mu-Metal cover or a longer power supply umbilical to place it far enough away.
Probably not an option, but rotating the PS 90 degrees in one of the three axes might help…