In article , Ian Iveson
wrote:
bcoombes wrote:

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

Without in anyway claiming to be an expert on these things I vaguely
seem to remember that most amp tests in the HI-Fi mags of the 1970's
and 80's had a square wave read out printed somewhere in the test. I
also *seem* to remember these were at 1k ...but of course these are
distant and increasingly dim memories.

Could be...I only started looking in the 90s. I did have some passing
interest much earlier but memories are very dim indeed. I have the
impression that older hi-fi mags commonly expected a narrower, more
hands-on and informed audience, and I guess some mags continued to
address that audience even when it had mostly disappeared.

Yes. If you compare issues from the period, say, before the mid 1970s and
nowdays the differences are quite stark. Back then it was routine to
publish quite detailed technical articles and to assume many readers could
at least solder, bend tin, and follow the gist of some equations, graphs,
etc. And so able to understand and decide for themselves the meaning of
such data.

Now the measured parts of reviews tend to be in a small boxout and often go
without any real explanation to allow readers to assess what they might or
might not be able to tell them.


It could also be that the kinds of problems highlighted by square wave
testing are no longer issues.

I suspect that depends on the items in question. So taking the example of
power amps I'd expect that most 'well designed' power amps in recent
decades would show no problems, and all a squarewave test would do would be
to confirm the bandwidth and any presence of an output network.

Alas, the snag here is my qualifier 'well designed'. It would not surprise
me if some of the more 'high end' products would reveal a set of problems.
Slew rate and/or current limiting for one. Possible also stability or other
problems.

This is because I have the feeling that some makers and designers may
simply be living on the fact that there may be problems which the review
methods used these days simply don't show up. Hence relying on the item
seeming OK in the system/circumstances/judgement of a few reviewers and
there being no info provided that readers could use to warn if in *their*
circumstances the amp might not work so well.

This is a general concern I've had growing uncomfortably for some years
now. So the lack of squarewave tests is just one perhaps minor aspect of
this wider possibility.

How much variety would be apparent in
comparing square wave tests of various audio amps these days?

Good question. :-)

Slainte,

Jim

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