Hi all!
I'm Mike and I am new here at diytube.com. I recently built a Darling tube amp. Unfortunately, I couldn't use the wonderful pcb. My enclosure is too small for that. Since I hadn't a small toroidal mains transformer in my scratch box I used a second enclosure for the psu like that:
The Darling sounds beautiful. I have, however, around 15 mV 50 Hz hum (I'm located in Germany) on the outputs when the inputs are left open (no source connected). With a source connected or terminated with a 100 ohms resistor it is dead quiet, and AC on the outputs drops from to 5 mV which is almost inaudible. Proper star grounding or external power supplies didn't change a thing. The best explanation seems to me that the inputs catch some noise. Can you confirm this effect? If not, do you have any ideas? Thanks in advance!
Mike