Strange 300b Push Pull Noise

[Richard]

Originally Posted by david

Hi All,
My mains was up to 253 volts at the weekend-a bit of a joke for 230v nominal! That pushed the ht on my 300b push pull and I did see a small red spot on one 300b, so I've taken out the 27k parallel resistors to reduce dissipation a little.

My HT is 595v, so I've ordered some resistors to drop the HT down a bit. I will fit these before the GZ37, so it will be running balanced and with the lower HT too.
David

Good move

[david]

Ok, my 25 watt 112 Ohm droppers arrived today and have duly been installed. The mains today is 247v, and my ht is now 569, and the cathodes measure at 98v, which is surely close enough.

And as Shian said a while ago, I swear the amp sounds sweeter, and hum has reduced even more (I measured it at 0.5mv, speakers connected, inputs shorted before adding the droppers).

Just hope with 25watt resistors things stay cool in there, but dropping around 7 or 8 watts, all should be OK.

Ok, no more good suggestions for adding anything else-I'm running out of space in there!

Seasons Greetings All,
David