[Iain Churches[_2_]]

"Arny Krueger" wrote in message
. ..
"Eeyore" wrote in
message
Iain Churches wrote:

But then SET amps traditionally
have little or no NFB and so are inherently stable

An absence of NFB **DOES NOT** make any ampliifer
'inherently stable'. Such an idea is pure horse manure.

Yep, in fact NFB that is truely NFB never causes instability. Instability
only comes when a loop that is NFB in the mid band becomes positive
feedback due to phase shift, usually at the frequency extremes.

Good. Things are getting better round here. Arny has made a
statement on topic:-) The FB that may be negative at say 1kHz
may well swing through positive at say 120kHz.

A tube amp without feedback is, by definition, not prone to such
problems.


Iain