What’s the best choke placement to minimize hum in a tube amp?

[PaulGJ]

I’ve finally got my old tube amp chassis stripped down and I’m ready to start the rebuild, but I’m stuck on the power supply layout. I’m trying to decide if I should keep the original choke placement or move it closer to the output transformer to minimize hum, but I’m worried about lead dress and introducing new noise from the heater wiring.

[ScarlettAT]

I kept the choke in the original spot first, and the noise stayed the same once I finished the chassis harness. Then I moved it right next to the output transformer to shrink the supply loop; the hum dropped noticeably. I also routed the heater wiring away from the power rails and used a separate heater ground bus.

[Jeffrey85]

I tried moving it and then found a new issue: the heater leads started making a buzz when they ran parallel to the high voltage line. I cut the heater route and twisted the leads tighter.

[Justin.S]

Are you sure the real problem isn't grounding or the lead dress rather than choke position?

[Joseph_L]

I drifted away from the schematic and kept swapping wires; sometimes the change did nothing but I learned to measure ripple on the B+ and watch how the transformer pulls current during power up.