[Eeyore]

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.

Graham