Please note the interpolations.

On Oct 24, 3:42 pm, flipper wrote:

This is what I meant. People seem to be losing track of who said and
meant what.

I am not so sure that losing track is the correct description of what
is going on. It more-or-less started with a statement that a Certain
Amp was a Model for various reasons amongst which was an apparent
broad Class A operational range before it went to AB.

So, an amplifier *may* operate in Class A mode for some range based on
its design.

I may have missed something but as far as I can tell *that* is the
'argument'.

I don't think anyone would disagree even for a hummingbird heartbeat
that some AB amps have some range of A operation before they go AB. It
is how one would describe and represent the amp overall that is at
issue.

But it cannot, must not, nor should it be classified as a
Class A amp if it does not operate in Class A at all ranges.

I haven't seen anyone claim that a Class AB amp is 'actually' a Class
A amp, or should be 'classified' as an 'A' something, or any variation
of the theme.

Otherwise, what we have is a marketing ploy because as previously
stated: Class A = Good Class AB = Not So Good

I think you're worrying about something that no one in here is guilty
of and, near as I can tell, the 'argument' revolves around the claim
by Multi-grid:

"That both tubes are conducting does not mean it is
A. Have some respect... AB amps don't have any A power, that is why
there is a separate classification."

It would seem to me that with your comment above saying "an amplifier
*may* operate in Class A mode for some range" that you are disagreeing
with Multi-grid.

I do not necessarily agree with Douglas. I just find the rebuttals to
his statements mostly either technically inept (as from Andre) or
technically elegant (as from John) but beside the point.

Btw, just as a matter of discussion, I see where you're trying to go
with the V8 analogy but I don't think it holds, as given, because 2,
4, 6, and 8 cylinder operation is not a 'natural' consequence of the
'engine class V8' while 'A' and 'B' (loosely defined) are for 'Class
AB'.

Actually, it was John that postulated a series of controls on an AB
amp that would force it (hold it in) to A class only. So, the analogy
of an 8 held to 4 or 6 cylinders only holds under that description.

I think a closer, albeit still 'stretched' quite a bit, analogy would
be if we defined 'engine classes' 4, 8 and "4-8," and then pondered if
a 'Class 4-8' engine was operating 'Class 4' during the times when
only 4 of the cylinders were firing. If the definition for 'Class 4'
was "4 cylinders firing" then one might say it was, despite some
differences, since 4 cylinders are firing under those conditions; Akin
to 'Class A' being the tubes conducting 360 degrees, a situation that
occurs in Class AB amps under certain conditions.

Oh, the entire engine analogy is stretched more than taffy on a hot
day in Atlantic City. But for all that, it is as valid as any other
points made along the line in this particular thread - again excepting
the direct contributions from Patrick which are right into the nitty-
gritty of the situation.

And one might wish to talk about under what conditions the 'Class 4-8'
engine makes the transition from 'Class 4' to 'Class 8' operation
because if it did so at the slightest hint of needing more power it
might make for 'zippy' performance at the expense of fuel efficiency
while a 'Class 4-8' engine reluctant to do so might be more efficient
at the expense of 'zippy' throttle response. But, IMO, saying "it's
Class 4-8, period, there is no Class 4 power" simply serves to obscure
it's operation for no useful purpose.

Well, it ain't nohow a "4-only" and it ain't nohow an "8-only", so it
must be something else. The only accurate label would be a "4-8". That
it operates in either mode is a function of its design. But it belongs
to neither unique class.

It might also be useful to point out, as you did, that 'Class 4'
operation of a 'Class 4-8' engine is not '100% equivalent' to 'Class
4' operation in a true 'Class 4' engine (depending on how well
designed each is) because you're dragging along dead cylinders, a
necessary consequence of it being a 'Class 4-8' engine, and, by the
same token, 'Class A' operation in a Class AB amp is not '100%
equivalent' to a true Class A amplifier (depending on how well
designed each is) for the same reason: the 'Class A' region of a Class
AB amp is compromised by the necessities of it being a Class AB amp.

Yep. And that is contributory to the point but not critical to it.

However, there's nothing in the 'Class' definitions that speaks to
'optimal', 'well designed', or 'equivalencies'.

Amen to that! There is quite a bit of ineffable crap out there. Some
of it is very expensive and uses very expensive boutique-type tubes
for no other reason than that they are expensive boutique tubes -
certainly not for the quality of the signal coming out of them. Why,
even their makers and defenders will wax poetic about how these amps
"add coloration" to the signal that makes them an "instrument in their
own right" and such twaddle. It is those sorts who will wax poetic
about that little bit of "Class A" operation in an AB-designed amp as
some great virtue. In point of fact, this would necessarily require
that the AB operation of the same amp is somehow faulty. Otherwise a
properly designed amp would be A only and t'h*ll with the headroom.

Once again, unless we are dealing in an Orwellian world, it just isn't
necessarily so.

Peter Wieck
Wyncote, PA