" wrote:

What about the use of modern materials to reduce cone break up ?

Not to mention in all aspects of engineering - the use of CAD / somputer
modelling to optimise designs

Yikes.... I have a 1969-executed-in-1971 design sitting on my bench
with "true complementary pair" outputs.

That would be a very early example indeed. Sadly not of much help given the
following info.

That it also used interstage
transformers and other Jurassic-vintage throwbacks is not relevant to
your statement.

Actually it is. It shows that such Jurassic designs were still being
implemented in 1971 ! Kinda blows that 'no advances in the last 35 yrs' claim
out the window nicely !

Cones that break up under any amplifier power below clipping are poorly
designed whether in 1951 or 2021. Why even suggest otherwise?

Cones break up *way* below clipping power. Just look at typical HF
performance.

CAD is a method, not a design. Computers model where previously actual
experiments had to take place.

And so fast that many possible iterations can be tried where previously it
was totally impractical. It *has* revolutionised design in every single
branch of engineering.

Admittedly many blind alleys are avoided
this way, but perhaps/maybe a risky-but-successful design as well.
However, I do know -one- speaker designer who believes that computer
modeling allows him to go down some experimental paths that he could
not have afforded otherwise... so it is a mixed blessing that I agree
has done more good than harm overall.

I'm pleased to see you recognise that. I fail to see how it's 'mixed
blessings' though.

That it is my opinion that he has
a tin ear and his products are useful only for announcing train
arrivals at the local commuter rail station is not relevant either.

Now, cutting directly to the chase... if an amplifier will produce a
flat response at say.... 60 watts/rms from say.... 5hz - 50khz, at less
than say.... 0.25THD, with a S/N ratio of 90dB-or-better, it is a
pretty good design... maybe??

0.25% THD hardly qualifies as a pretty good design these days. It's hard for
a competent designer to exceed 0.025% today even when cutting costs.

Even if it uses a steam engine and burns
coal? This was done in 1969.... as a mass-produced product, yet.
Improvements on that design would be "around the edges" perhaps?
Graham, with all due respect, you need to read for content and separate
your emotions from the discussion at hand.

Emotions don't come into the above. Merely modern design engineering
principles.

Graham