"Audio Empire" wrote in message
On Sat, 5 Mar 2011 11:17:39 -0800, Dick Pierce wrote
(in article ):
But, no insult intended, your math and physics are rather
incomplete. The math and physics describing the non-ideal
behavior of resistors is rather much richer than that,
and has been for half a century and more. To your point: both
the observed behavior of various resistor formulations
such as carbon composition, carbon film, metal film and
so on is something that was well known and well
understood by bachelor degree level EE's graduating in the early
1970's.
It was known to me in the early 1960s, when I was just barely a teenager,
and had not graduated from High School, let alone university.
I graduated in the 1960's, but that's neither here nor there.
At lot depends on your experience and contining education since then.
I'm trying to make a point about how component
choice can affect amplifier performance.
Obviously, you lack actual reliable and scientific hands-on experiments.
When I was 13-14 I was doing parts upgrades on amps and preamps and
measuring and doing reliable listening tests of the results. I had a rich
stash of very high quality parts from the military suplus markets.
I realize that there are tools available today that a designer can use
which does take all of those things into consideration.
You were just singing a vastly different song.
There is also the experience of the designer at work here.
I see no evidence of that.
No competent designer is going to use carbon comp
resistors in an audio circuit these days,
That's because they are largely unobtainium. Carbon comp resistors went the
way of the dodo bird and LPs in the early 70s, if memory serves.
nor are they going to use tantalum caps to couple between stages
That's because regular electrolytics are so much better, now.
but some cheap mass-market electronics were still using
aluminum electrolytics to couple audio stages, and not
too long ago either (don't know about today). Heck the
ubiquitous Sony PCM-1610, 1620, and 1630 family of
digital processors which were used almost exclusively in
the early days of CDs to master them, were full of
aluminum electrolytic capacitors between (741 op-amp)
filled stages.
So what? There's zero evidence that electroltics cause audible problems when
appropriately used, which includes in and across the signal path.
Had a more complete physical and mathematical model been
used in your design from the get go, the final properties
of the circuit, such as the noise, would have been far
more acccurately predicted.
Of course it would.
Doing so has been commonplace for decades.
Further, once built and even before listeing, the
detailed
noise properties of the circuit will have been easily
measurable, along with many other easily quantifiable and
trivially measurable properties far beyond the usual
simple-
minded and largely irrelevant measures such as frequeny
response, THD, and simple broadband S/N.
Agreed.
But to indict the entire realm of audio "maths and
physics"
based on what really is a very limited understanding of
the actual math and physics that are widely practiced in
professional engineering realm (admittedly, a fraternity
that is not as well represented in the realm of high-end
audio designers as eslewhere) is, well, ineffective.
Nobody's "indicting" anything.
Really?
What you mischaracterize
as a "limited understanding of the actual math and
physics that are widely practiced in the professional
engineering realm.."
One hidden benefit of the use of modeling software is that the detailed
properties of the components become part of the model when the Bill Of
Materials is typed in.
is, in reality, only an extreme,
almost hyperbolic example of how component choice
"could", conceivably affect the performance of a decent
amplifier design.
The idea that one has to go to extremes to have a good sounding audio
compoent is just another audiophile myth.