Arny Krueger wrote:

"Pooh Bear" wrote in message
...


" wrote:

not much has changed in the last.... 35 years for solid-state excepting
around the edges.

You are JOKING !

You can't understand much about modern solid state design.

Even the true complementary pair was essentially unknown 35 yrs ago. And
that's for starters !

35 years ago was 1971, and I had been building and repairing SS amps for
about 8 years at the time.

The true complementary pair was well-known and widely used in 1971. For
example, they were widely used as drivers for quasi-complementary output
stages. Common part numbers were 2N3053 and 2N4037 if memory serves.

As *drivers* !!!!!!!!!!!

Please pay attention Arny !

I said ' complementary output ' - NOT - ' quasi-complementary output' ! There's
a HUGE difference.Not least in the sound.


There were some issues with the costs of high powered complementary pairs,
but their use was well-known. Bart Locanthi is well-known for his design of
the full complementary "T circuit" which appeared in a JBL power amp in the
mid - 1960s. Please see this 1967 article
http://users.ece.gatech.edu/~mleach/.../tcir/tcir.pdf My recollection
is that the amp was new on the market at the time this article was
published.

I may get round to reading that since you recommend it.

The simple truth however is that it was device technology advances that made
proper fully-complementary outputs viable only in the mid 70s.


Speakers will use
better materials (sometimes) and tighter tolerances (sometimes), but
their essential function is unchanged. That the better materials and
tighter tolerances make them more efficient is a very good thing.

Also better materials for magnets.

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

Or at least control it.

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

Agreed. Circuit modeling has greatly assisted the design of low distortion
circuits.

It's actually a fascinating area. As long ago as 1989 I was using Mathcad to
create my own models for amplifier gain/phase/stability calculations. Today's
off the shelf packages make it so much easier but the user may not fully
understand the underlying principles any more though.

Graham