In article , Arny Krueger
writes
"Eeyore" wrote in
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Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:

As my distortion measuring gear progressed to residuals
in below 0.01% there was always a mixed bag of
measurable differences. But they were arguably quite
small, given that its often darn hard to hear
distortion below 0.1% or so.

I had a 'revalation' that blew away that idea about 30
years ago.

Do tell.

I made my last try at making small amounts of nonlinear
distortion audible about 5 years ago, and the 0.1%
number was the fruit of that effort. My results aren't
that dissimilar from those found in J. Robert Stuart
(Meridian Audio), "Digital Audio for the Future", Audio,
3/98 pp 30-37. Stuart isn't exactly conservative on this
topic. I know of nobody credible who has claimed lower
thresholds for audibilty.

In my case my I was comparing the H-H TPA 50 amplifier (
a fairly classic A/B design of its era and quite widely
used in pro-audio - including the BBC ) with ~ 0.1% THD
on the spec sheet with a friend's recently assembled kit
ampliifer using Crimson Elektrik modules. These used a
rather more 'state of the art' design with the then new
high speed Japanese output devices ( the H-H used
Motorola darlingtons ).

Lets just say the difference wasn't subtle !

The H-H sounded gritty by comparison to the much smoother
Crimson.

I had to search high and low to find much out about H-H brand equipment.
Apparently they were popular in the late 70s. I wouldn't try to generalize
very much related to just one sample of such an ancient obscure piece.



I recall them and they did sound very rough. But they were mainly used
for PA and such applications......
--
Tony Sayer