heaters

[gtrboy]

why dont PCB heater traces cause hum when they are straight but wire needs to be twisted?

[Steve Conner]

Have you ever tried twisting PCB tracks? It's not easy. So designers have to just accept that heater traces on PCBs will radiate more magnetic field than twisted wires in a P2P amp do, and move sensitive stuff on the PCB further away if it turns out to be a problem in prototypes.