My First Tube Radio Restoration Log

[Chryseus]

Old tube radios (and also tube amplifiers) usually have AC heating for the tubes. Then, the rectification is usually not perfect. There is the "trick" to inject some AC (or "rectified" DC) at a 180° phase shift, which in turn will cancel out some of that. I have seen a lot of professional tube amps (for example the 30 watts amp in the Klein+Hummel OX studion monitors) that had a pot especially for that purpose: to adjust the amount of "directly injected hum" that cancels it out.

Or simplified: -1 + +1 = 0....

Greetings,

Chris

That's a pretty neat idea, thanks!