Hey guys, I come to you dejected and defeated after trying to fix the hum in my tube amplifier. This amplifier is for a school project, and I designed it myself. I have rewired it to shorten most of the wires, but I still can't solve the hum. Here are some notes that may help anyone willing to assist: The hum persists when I remove the input tube 1. I am running the amp without a potentiometer currently, but when I added a resistor on the input to simulate a pot, nothing changed 2. Removing the B+ does not affect the hum 3. I tried using a 2.5-0-2.5 transformer to supply AC to the tubes (paralleled) but it increased the hum 4. Shorting the output eliminates hum completely (obviously) 5. Bottlehead crack plugged in to the same outlet produces 0 hum, so the issue isn't my mains line 6. I have used a scope (not a very good one, I don't think) 7. Adding/removing grid leak resistors had 0 effect, as did shorting the grids to ground I am using the 21st Century Maida Regulator from Tom Christiansen for B+, and using Pete Millet Regulated Supplies for my 2A3 filaments. The amp is built with a single 6SN7 driving one 2A3 per side, it is single ended. I am not currently looking for information on upgrades to my design, I just need help getting rid of the hum. I have tried searching for ground loops, changing resistors, everything I know to try, but I haven't been able to solve it. Here is my schematic, yes it is pretty simple, and believe me, I am thoroughly embarrassed to be seeking help on such a simple project Here is my grounding scheme HERE ARE BUILD PICS, THE CYAN REPRESENTS THE GROUND LINES IN THE BOTTOM 2 Any help is greatly appreciated. I love you all. Thanks!