Hand wiring in a tube amp is a good idea. In tube amps with higher voltages, its possible for an output tube to create flyback voltages between the plate and cathode connections. This can cause arcing on the tube socket and if mounted on a circuit board, arcing on the board too. Flyback voltages can occur when the amp is driven into clipping and an output tube is driven into cutoff- at this point the magnetic field in the output transformer collapses and creates a very high voltage- similar to how a spark coil works in a car.
If the amp is hand-wired, sockets are much easier to replace! If there is a circuit board that is damaged by arcing, it can be tricky to repair.
The other issue of circuit boards is heat. Power tubes run hot and this can degrade the circuit board over time. This can be particularly problematic in tropical environments, where its a good idea for the circuit board to have what is known as a 'conformal coating' which prevents corrosion.
Finally, the design and quality of the traces and pads of the circuit board can have a big effect on how repairable the board is- a poorly designed pad (as seen in 1980s ARC) does not survive component replacement very well. So if a circuit board is employed in tube equipment for best longevity it should be 1/8" thick with the heaviest traces, employing a conformal coating, with good pad design and ample cooling holes around any components that run hot.
If the amp is hand-wired, sockets are much easier to replace! If there is a circuit board that is damaged by arcing, it can be tricky to repair.
The other issue of circuit boards is heat. Power tubes run hot and this can degrade the circuit board over time. This can be particularly problematic in tropical environments, where its a good idea for the circuit board to have what is known as a 'conformal coating' which prevents corrosion.
Finally, the design and quality of the traces and pads of the circuit board can have a big effect on how repairable the board is- a poorly designed pad (as seen in 1980s ARC) does not survive component replacement very well. So if a circuit board is employed in tube equipment for best longevity it should be 1/8" thick with the heaviest traces, employing a conformal coating, with good pad design and ample cooling holes around any components that run hot.