[Arran]

Kirk;
  I should also add that in substituting a tube rectifier with a silicon diode or diodes that the B+ will now be full on before the tube heaters have had a chance to warm up, so in the past in things such as TV sets they used to incorporate a thermistor in line with the high voltage to keep the voltage down for a minute or so. The voltage spike can also hard on the filter caps, with no load the B+ can hit 400 volts or more before the tubes warm up, it's probably less of an issue with modern electrolytic caps but such spikes could cause the old style ones to short out.
Regards
Arran