On Oct 24, 1:37 am, Andre Jute wrote:
Multi-grid wrote:
Class A has nothing to do with dissipation either.
Then Poopie wrote:
The definition of Class A is very simple. It requires that the output
device(s) never cease conducting under any signal condition.

Then Mickhttp://www.nascom.infoandhttp://mixpix.batcave.netwrote:

Correct. A class AB amp fulfills this up to the point where one side
starts to turn off.

I can see what you're getting at, Poopie, and so can Mick apparently,
but I don't think I want to wear your definition where it says "under
any signal condition". That's most misleading, especially with a
newbie on the board who stubbornly keeps claiming signal has nothing
to do with Class A. Any power stage that is hitherto Class A can
driven to cutoff by simply increasing the signal until the output cuts
out at either zero current or zero voltage.

In any and all cases, Class A is defined, though usually implicitly
rather than explcitly, as at a particular, *limited* signal voltage. I
therefore prefer the definition of Class A which says simply:
***Class A operating conditions do not permit the output device to
cease conducting.***
If you insist on describing the signal condition, you could add the
words *at the design or intended or specified signal*.

As for Dougles Multi-grid's silly insistence that signal and
dissipation have nothing to do with Class A operation, thanks for the
giggle, sonny, but you'd better hit the books lots more before you
seek entry to this club.

They don't Andre, no matter how much you claim they do. Class A, is as
simple as you first stated it:

***Class A operating conditions do not permit the output device to
cease conducting.***

It should get the addition that remote cut off behaviour is not
included.

In particular, you should pay attention to
this, which often comes as a bolt from the blue to repair hacks like
you, who tend to assume that the parameters are godgiven and fixed:
the *designer* chooses the plate voltage and negative bias, that sets
the current at quiescence, through which the designer then runs the
loadline at a particular angle when he chooses a primary impedance for
his output transformer, the slope of the loadline determining how far
the quiescent point is from current cutoff (or voltage cutoff...), and
that in turn defines the signal voltage that can be put in for Class A
operation, which in turn defines the output power. Thus the signal
level has everything to do with Class A operation, and in turn defines
maximum possible dissipation from Class A operation. Cruise my
netsite; all this is explained in both words and pictures.


I make no such assumptions. That you'd think I would only shows your
limitations. Stay off this group-killing personal attacking if you
please. Isn't one war named after you enough?
cheers,
Douglas