On Tue, 22 Jul 2003 20:36:09 +0100, Nick Gorham
wrote:

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.

It's in the total impedance to ground, including the internal
resistances of the NiCad and the triode cathode, also the internal
feedback from anode to grid. That's why the pentode was developed, to
reduce this internal feedback and thereby increase gain.

To be fair, this is certainly about as low a feedback value as you can
get from a triode, with the NiCad bias!
--

Stewart Pinkerton | Music is Art - Audio is Engineering