Although I haven't put the 'scope on it yet I have a suspicion that my QQV amp is oscillating, as once it's been running for a few minutes it becomes distorted, as though it's running out of power. I will investigate more closely when on my next days off but meanwhile, a question.
It has 1K grid stoppers on the grids of the QQVs and the first stage, and I'm wondering what they actually do and how their value is arrived at. If the input impedance of the valves is up in the megohm region, how does a 1K resistor in series make any difference?
How do grid stoppers work?
#2
There's nowhere you can be that isn't where you're meant to be