Heater Transformer Upgrade

[soulminer]

I am tempted to remove the heater wiring for the 300Bs in my 300B PSEs from the original mains transformer supplied windings to some seperate 230v/5v 20VA EI transformers from RS. I have read that doing this can not only give the original mains transformer an easier time (2.4 amps less it has to pump out), but can also reduce hum induced in the heater windings from the HT windings on transformers without winding shielding.

My monoblocs are deathly silent on switch on with the hum buckers tweaked, but get slightly louder and louder as they heat up. I think this hum is on the heaters of the 300Bs as it is there with all other valves removed or the inputs shorted out with valves in. It seems less noticeable with a pair of TJ meshplates fitted than with a pair of EH GGs fitted. Not sure why.

I was going to fit the RS transformers inside the chassis at the back, and use the two 5v AC outputs to heat each DHT. I was hoping that not using the other two 5v windings would keep the original WAD mains transformers slightly cooler and maybe even reduce mechanical noise/hum slightly too.

I love the sound of the amps and the EH GG 300Bs (and their low cost), but am getting a little tired of this low-level drone when they have been on for an hour or more.

Would this little modification cure this do you think, or would I be wasting my time?

Also, the RS transformers are 230v primary -> 2 x 5v secondaries @ 20VA giving an output current of 2 amps. Is this per winding or for both windings in parallel (ie each winding can supply only 1 amp)?

Obviously the 300Bs need 1.2 amps each. Are these RS transformers a little weedy or will they do the job? I have seen a 30VA transformer on eBay that supplies 3 x 5v at 2 amps each, so I am guessing that the RS one will supply 2A each too with each 5v/2A winding being 10VA. Am I correct?

The RS stock number is 805-029

Cheers,