Barrymagrec
pfm Member
On the point of rectifiers, all valve rectifiers give a soft star, the difference between directly heated types such as 5Y3, 5U4, 5R4, U50, U52 and indirectly heated types such as GZ32, GZ34, EZ80/81, 5Z4, 54KU is that directly heated types come up within a second or two putting a surge voltage on the reservoir caps whereas indirectly heated types take much longer to warmup so that by the time they can supply current the other valves in the amplifier are also warm and able to conduct so preventing the surge.
Of course directly heated output triodes such as PX5 ,PX25 and 300B also warm up very quickly so a directly heated rectifier is less of a problem.
Of course directly heated output triodes such as PX5 ,PX25 and 300B also warm up very quickly so a directly heated rectifier is less of a problem.