In message , Nick Gorham
writes
Stewart Pinkerton wrote:

*All* amps use feedback, but some don't use *global* feedback, leading
to a common claim about 'zero feedback' valve amps.

Been thinking about this, where is the feedback in a triode, with a
NiCad between its cathode and ground ?

I use this in my phono stage, and I can't for the life of me, see any
feedback.

--
Nick


The low internal impedance in a triode is because of the internal
feedback between the anode and the grid. Although the feedback
mechanism is obvious at high frequencies (Miller effect) the varying
voltage on the anode couples to the grid as an NFB mechanism even at LF.

Thinking of directly heated triodes, I see the pair of DA100s that I'm
selling on Ebay are up to 186 pounds.
--
Chris Morriss