Audio signal on B+

[Shamsyrup]

Hope everyone is doing fine. I am getting audio signal on my B+ line. Is it normal ? I have also taken some measurements on the DC filtering stages. Attached all the pictures. All measurements were taken when the amp was fully cranked up. Are these measurements normal ?

Thank you.

 

[Tom-s]

You're watching power supply ripple.

Edit. That how i interpret the power supply filter results. But i can't explain the 1khz tone you have on the B+?

 

[Shamsyrup]

What about the audio signal on B+ ? That is not power supply ripple.

The 1khz tone was fed to the input of the amp through a function generator.

 

[Tom-s]

That's your amplifier functioning.

 

[Shamsyrup]

So it is totally normal to see audio signals on high voltage DC B+ power rail ?

 

[Paul Joppa]

The output signal current flows through the power supply, and the impedance of a 220uF cap at 1000Hz is about 0.7 ohms, so there will be some signal.

What was the signal level? And what was the load (i.e. headphones plugged in? what impedance?)

 

[Shamsyrup]

Signal level was 1 volt and the load impedance  was 300ohms.