"John Atkinson" wrote in message
om...
(Audio Guy) wrote in message
...
In article ,
(John Atkinson) writes:
(Audio Guy) wrote on r.a.h-e in message
...
Audio is a trivial application, they learn about power supply
design and amplification, which is pretty much all there is to
audio amplifiers, in their early years and then go on to much more
interesting and challenging concepts.
I see statements like this from time to time, yet I am not so sure
that audio design is "trivial." There are not many other design fields
where an amplifier: has to provide up to 30dB of voltage gain; act as
a
voltage source into a wide and arbitrary range of load impedances
and do so in an unconditionally stable manner; have a passband noise
contribution at least 90dB down from 1W into 8 ohms, no matter what
its voltage gain and ultimate power delivery; have distortion
components under all load conditions that are below the threshold of
hearing no matter what the program material is; and do all the above
over at least three-decade, ie, a 10-octave passband.
Thoughts, gentlemen? I would suggest that designing, say, a typical RF
amplifier is, by comparison, "trivial" but, of course, I may just be
missing something :-)
Sure, take my words out of context.
You left out the previous part that qualifies them:
"Audiophiles don't realize that audio is an extremely small
part of electrical engineering and that very, very few schools even
teach courses in the subject. It isn't where the money is, nor is it
where the interest is for EE students. EEs like to make ICs or design
computers or work in motor control or design antennas or work in
telecom."
My apologies "audioguy" but I don't see how this paragraph changes the
meaning of the words you wrote about audio amplifier design. It doesn't
matter _ why_ electronic engineers feel audio is a "trivial" application,
only that they do, and that is what I was addressing. Note that I feel
that audio amplifier design is far from trivial. If you look at the
list of attributes I listed for an ideal audio amplifier, I can think of
almost none, of all the designs I have tested for Stereophile, that
achieve that level of performance.
John Atkinson
Editor, Stereophile
Many words slip into a discourse through inadvertent prejudice or
association, rather than intended meaning.
I think what Audioguy meant to say is that audio amplification is regarded
as trivial not because it is, but because it is bereft of the prestige that
comes with working in a field with actively advancing fundamentals.
For example, Kalman filtering is no less important now than in the early
1960's, yet only the specialists who actually insert these very canonical
algorithms into microcontrollers pay any attention.
Examples of recent, really remarkable advances which incorporate elements
of circuit theory are
high speed serial bus transducers, such as RAMBUS or USB
flash A/D
the neodymium lightwave amplfier
Sun's capacitive chip interface
and a little bit earlier: the gyrator
By contrast, designing and building an audio amplifier is somewhat like
cutting a diamond. It has become an almost timeless skill.
But I say to you, John, that nobody has come up with a reasonable set of
figures of merit. I still can't look at a set of your graphs and predict how
an amp will sound. That's a disconnect.