Intermittent hum PSU SimpleSE

[cbutterworth]

I don’t know if I can remember the specs on my SimpleSE as had it for a good few years. However, on occasion, I have had audible hum from the power transformer.

IIRC: Hammond 374bx
Voltage is around 440 on the tubes, running KT88 with cathode resistor around 560 ohm. Current should be something like 73mA per tube. Even with two tubes and the input tube, current draw is way less than transformer specs.

I have the optional choke and only rune the amp in SE mode.

Sometimes, there is zero hum, when there is, a repowering can fix it, but I don’t like doing that as I worry about inrush from a warm rectifier.

Where would I begin diagnosis?

Suppose, I could check mains voltage, maybe try a different filters outlet in my power conditioner.

Any ideas?

 

[boywonder]

Is the transformer humming when you put your ear next to it? ......or are you hearing 60hz hum through the speakers?


Transformers hum......laminations vibrate......you can try to tighten the lamination screws....

 

[cbutterworth]

It’s the transformer not at the speakers. Sometimes it is audible from where I sit, although difficult to hear through music.

I’ll give the screws a little tighten. Maybe mount it on rubber pads, etc.

Thanks,
Charlie