transformer noise

[vitalstates]

I have just made some mods to son of rocky and my mains transformer has started to buzz/hum, loud enough to hear across a quiet room. The question is ....is this coincidence or the result of my mods.

After some advice I upped the first cap on the pi filter from 8 to 16 uf. Somebody at EF3 suggested that my parallel GZ32s were not in fact GZ32 at all but some direct heated valves badged as GZ32. I havnt a clue what they are but a number of people have suggested that 16 is a better value all round.

Can anybody suggest whether this change would cause a transformer to start humming.

I have been searching for references but all the obvious books seem a bit shy on valve rectification and would rather talk chapter and verse about solid state.

Regards

Ed