Amp plays on standby!

[g1]

I measured a few PTs for capacitance between HV winding and heater winding or frame.
Results were between 100pFand 1000pF.
1nF means an impedance of 2.7M at 60Hz.

My question, I meant how much power do we need to call it 'real'.
We only need fractions of a watt to be audible at the speaker.

[g1]

BTW, there are currently no tubes in this amp while I am making these tests.

This was the next test I was going to ask you to do. To me this proves it is not related to the standby (high voltage) and is possibly normal for this amp.
Your statement that the amp 'should be quiet' is not absolute unless you have compared to another unit of the same model. How loud is this output when in standby mode with power tubes pulled?

[Helmholtz]

My question, I meant how much power do we need to call it 'real'.
We only need fractions of a watt to be audible at the speaker.

The capacitive coupling would only allow for an output in the µW range..

[g1]

The capacitive coupling would only allow for an output in the µW range..

Ok. Well, my theories were only an attempt to explain how the power tubes could be doing the work. But they are not installed and still the sound is there, so it is not relevant anyway. It seems to have nothing to do with the high voltage supply or standby switch.

[nosaj]

Singing transformer?
nosaj

[x-pro]

What is said above and beyond is conjecture.
What position is S5 in? Is there a true ground connection at the outlet?

[Axtman]

X-pro: Where is R65?

[x-pro]

over T1

[g1]

"GND" - 2 pieces!

How can voltage at C3 or C4 have any affect if power tubes are removed?

[x-pro]

The point about the voltage phantom.
I'm not claiming that there is enough energy to rock the speaker.
Why is there potential at the output capacitor in a unipolar powered amplifier at its output pin with no load?
The author is either measuring incorrectly, or there are some connections in the design for leakage currents.

Miracles don't happen

[35L6]

Could the preamp drive the OT through the feedback loop ?

[sugeda]

525V discharges through R1 and R2 (220k x 1x) when stand-by

[x-pro]

When you do put it in standby the volume and LED light slowly decreases probably due to discharging capacitors. But, there is still some voltage (about +30v) on the plus side of C3. I cannot figure out where the voltage could be coming from. Could C1 or C2 be leaky? I thought it might be the switch so I pulled it out of the circuit and there still is voltage! Very puzzling.

Honestly, I too am as confused as many experts on the forum.

[g1]

Sometimes old caps will 'self-charge'. I would think the 220K across the cap would discharge it, but can't say 100%.
That might explain the voltage on C3. But once again, the power tubes are removed, so the voltage on the cap in the HV supply should have no bearing on the sound at the output..

[x-pro]

Wholeheartedly agree.
Maybe the sound is not coming from the speaker, but from a spring reverb that is poorly acoustically shielded?
I really haven't heard the sound from it. It's how much power you have to put in there to make it emit))).
Just the latest fantasy.