I'll probably regret stirring this stew............
> I think you believe I was saying that....
> ...Not so. I was referring to only the name
I understood you were saying "push-pull, class A" doesn't sit right. Since class A push-pull IS (in electronic theory) a very clear object of study, I think it should "sit right" in your mind. It makes discussions clearer.
> I would be taking offense that they are already assuming I don't know quite a lot of obvious stuff
None of this stuff is "obvious". It has to be learned. And eventually organized for easier reference and discussion.
Note too that this is a PUBLIC forum with 9000 nominal members, 20,000(!) views on some threads... most of the regulars are very aware that many members are "silently" reading and many need to be brought up-to-speed on some points that the participants already know.
I don't see "idiot" anywhere except your post. That's completely off-base.
> Why do a lot of engineers or moderators launch
Don't be over-awed by a moderator hat. Here, "moderator" is un-paid extra duties. John won't stay away, so Ethan gave him a mop in case he sees a mess (spam, nasty-talk). But he's here to learn/share/teach because he wants to be here, not to crack heads.
> This is much ado about semantics
Indeed.
The semantics of amplifiers are well-organized, in theory.
There's small-signal (invariably SE A).
Next chapter you push the amp to the max for A Power.
Next chapter is push-pull (or push-push... totem or transformer does not change the theory). Some nice improvements.
Now back up. Off-bias the amp for class B. Show that SE class B won't make "undistorted audio", but two antiphase B units can combine for "undistorted", AND with wonderful improvement in idle-heat and max-power efficiency.
In here the text should touch class C, but there's no "undistorted audio" possible here (it was very important that young EEs learn their C because radio was major jobs.)
Comp/quasi-comp, totem or transformer (output or driver) are implementation details. Yes, this is critical. But it isn't basic A or B, SE or P-P, as the thread-starter question asked.
> early cheap transistor radios and consumer gear ...were predominantly class A discrete, and often delivered questionable audio quality...
Not so predominantly. Huge numbers of pocket radios (and other gear) used "Class AB/B" outputs with such sloppy biasing that they would not play soft. (The alternative with poor tolerances was possible runaway or bias-trim, both bad for business. Implementation details.)
> place an imaginary load on it to see if it leaves A
If it leaves "A", it better be designed for "B" operation; and surely is.
If it was _sold_ as "A!", and leaves A, that's marketing misrepresentation. The sins of marketing are too numerous to count.
> "PURE" Push-pull Class-A (at least in my book)
"Equal and opposite swings" is pure enough to be "push-pull class A". Your book seems to overlay this with requirement to be push-pull class A in ALL stages to be "PURE". OK, but that's one box of the 69-box chain from artist to CD/MP3 to speaker. Some days we have to take one stage at a time.
> SRPP -- Is it a push-pull or push-push? ...
Broskie's analysis shows it is both depending on load (not level).
Oh.... "push-pull" is catchy but open to confusion. "Equal and opposite signal swings" would be a better phrase, but won't roll off the tongue. "Equal and opposite signal swings" can be done either with transformer or totem-pole... implementation detail.
There "is" also a "push-push" mode. Signal currents are NOT opposite. (And to be useful, they must also be unequal.) This is a "bad" mode, wasteful. FWIW, both the WCF and SRPP enter this mode for large load impedances (larger than Rp). To get 1mA _signal_ current, they shift 2mA in top device and 1mA in bottom device. 2mA-1mA= 1mA output signal. But the pair is working 3X harder than necessary. You can, for hi-Z, get a better amp with both devices parallel resistor-loaded (but this sacrifices the option for useful power in lower-Z loads). I've only seen this as totem-pole. I guess when you have to pay for a transformer you don't consider such wasteful working. (Actually there may be a tube guitar amp which can be mis-tuned this way for less power more flavor.)
> think of the J.L.H. as being a class A common emitter stage having an active load
It is not any sort of emitter follower. There is an input section, then a bootstrapped-resistor (or CCS) loaded driver, then two same-type output devices. The driver acts as a differential OUTput current source. 200mA down through the resistor is split 100mA to each output idle, 0-200mA to the top and 200-0mA to the bottom. The current sources have voltage compliance (are not low-Z). This current is multiplied by hFE of the output devices to be load current. 0A-1A-2A in top device, 2A-1A-0A bottom. The difference, +/-2A, is load current. Output impedance (before NFB) is high.