[morzh]

There is plenty of info on forums.

Basically you do not want just to replace (the diodes like 1N4007 can be used) - you also need a resistor to emulate the tube rectification.
Another thing is, it takes time for the tube to warm up and diodes are instant, so if there is some reliance upon tubes being hot at the same time as the rectifier, this is not the case anymore and the high voltage will be present before the load is applied to lower it.