Jim Lesurf wrote:

The cd-player source argument is a red herring, surely?

Not sure what you mean. It was one of the domestic sources
used purely as
an example of the kind of signal source normal users will
be rather more
likely to be listening to than a test-bench squarewave
generator.

I mean that the cd player is irrelevant because no-one would
use one now, or then, as a source for a square wave test.
It's not as if suitable sources are no longer available or
inferior to what they were, so what could the source have to
do with the disappearance of the test?

Listening to square-wave generators was no more common then
than now, either, so there's another red herring.

Especially combined with the arbitrary example of a 5k
square wave. 1k
would give you plenty harmonics, especially if you
weren't daft and used
a proper source.

Erm, the point isn't just having 'plenty of harmonics'. It
is the finite
bandwidths, slew rates, current demands, etc. And how
these can be somewhat
different for ordinary domestic examples than for a bench
test of the kind
that was once routine.

I can't quite see how those two sentences fit together, or
what you intend to mean by either of them.

What I meant was that, when you argue that a cd source can
only accomodate one of the odd harmonics necessary for a
decent 5k square wave, it can support nine odd harmonics of
1k, which is plenty for a quite good 1k square wave, and a
half-decent generator that could be easily acquired by a
reviewer will likely offer a squarer square wave than one
used by reviewers or DIY-equipped readers in the past. In
short, the quality of the source appears to me to have no
bearing whatsoever on the demise of the square-wave test.

Also, as mentioned in the preamble, this was prompted by
looking at
material on loudspeaker cables of tests using bench
sources which brought
to my mind the way similar things were done in the past in
reviews, etc.

You conclude that reviewers have abandoned the square
wave, but did
they ever use it much anyway?

Yes. It was very common a few decades ago in most HiFi
mags. Have a look at
Hi Fi News or similar back in the 1960s/1970s for example.

I think Stereophile still have some squarewave tests. IIRC
I've seen them
in issues in the last year or two. But they have
essentially vanished from
UK magazines.

A square wave test result seems to me
several levels of abstraction distant from what the
average audio
enthusiast might be interested in. It offered a
convenient method of
testing amplifiers for designers or home builders with
limited
equipment. It was never ideal because it superimposes
several tests
such that results need careful interpretive
disentanglement.

I agree.

When did it become common for 'scopes to have memory?
Perhaps it then
became unnecessary for the pulse to be repetitive.

IIRC I started using storage scopes back in the 1970s, and
also had
waveforms with pulsed/burst patterns with long gaps, etc.
But that was for
other kinds of work. I don't think that was common for
things like audio
mag reviews at the time.

But did they become so? What do mags use now instead? It
does seem that storage 'scopes were becoming common around
the time that square wave tests began to wane. Storks and
babies, maybe, not directly related but both linked to a
common theme. Hands-on engineering experience became less
common as machines became more complicated. Consequently,
interest in abstract technical tests was becoming less
common just as the capabilities of the test equipment was
rising. The classic story of alienation, I suppose. People
want nice pictures. Most of all, they want spectacular
destruction testing in exotic locations.

Don't you find it soul-destroying writing for HFN?

Ian