[murphyv310]

Originally Posted by Heatercathodeshort

Use the original U52/5U4G H.T. rectifier. J.

The 5U4/U52 are directly heated valves with a filament, although the surge is less than using a silicon or selenium rectifier, the voltage across the HT Line rises very quickly and doesn't stabilise to its running voltage until the load increases with the other valves warmed up.

On a set that is only used rarely I'd advocate using the likes of a GZ33 or GZ37 , being an indirectly heated valve the warm up time is much longer so its kinder to smoothing capacitors and other components, the peak surge voltage will never reach what it was with the 5U4 or silicon etc.