The amplifier does not require any maintenance. While the design is conservative, this is a
hard running amplifier, as single ended Class A operation is the least efficient operating
mode. In fifteen years the electrolytic power supply capacitors will get old. Depending on
usage, you will begin to have semiconductor and other failures between 10 and 50 years after
date of manufacture. Later, the sun will cool to a white dwarf, and after that the universe will
experience
heat death
.
Pass Product Philosophy and Design Theory
When I started designing amplifiers 25 years ago, solid state amplifiers had just achieved a
firm grasp on the market. Power and harmonic distortion numbers were king, and the largest
audio magazine said that amplifiers with the same specs sounded the same.
We have heard Triodes, Pentodes, Bipolar, VFET, Mosfet, TFET valves, IGBT, Hybrids, THD
distortion, IM distortion, TIM distortion, phase distortion, quantization, feedback, nested
feedback, no feedback, feed forward, Stasis, harmonic time alignment, high slew, Class AB,
Class A, Pure Class A, Class AA, Class A/AB, Class D, Class H, Constant bias, dynamic bias,
optical bias, Real Life Bias, Sustained Plateau Bias, big supplies, smart supplies, regulated
supplies, separate supplies, switching supplies, dynamic headroom, high current, balanced
inputs and balanced outputs.
Apart from digitally recorded source material, things have not changed very much in twenty
five years. Solid state amplifiers still dominate the market, the largest audio magazine still
doesn't hear the difference, and many audiophiles are still hanging on to their tubes. Leaving
aside the examples of marketing hype, we have a large number of attempts to improve the
sound of amplifiers, each attempting to address a hypothesized flaw in the performance.
Audiophiles have voted on the various designs with their pocketbooks, and products go down
in history as classics or are forgotten. The used market speaks eloquently: Marantz 9's
command a high price, while Dyna 120's are largely unwanted.
So far there has been a failure in the attempt to use specifications to characterize the
subtleties of sonic performance. Amplifiers with similar measurements are not equal, and
products with higher power, wider bandwidth, and lower distortion do not necessarily sound
better. Historically, that amplifier offering the most power, or the lowest IM distortion, or the
lowest THD, or the highest slew rate, or the lowest noise, has not become a classic or even
been more than a modest success.
For a long time there has been faith in the technical community that eventually some objective
analysis would reconcile critical listener's subjective experience with laboratory measurement.
Perhaps this will occur, but in the meantime, audiophiles largely reject bench specifications as
an indicator of audio quality. This is appropriate. Appreciation of audio is a subjective human
experience. We should no more let numbers define audio quality than we would let chemical
analysis be the arbiter of fine wines. Measurements can provide a measure of insight, but
are no substitute for human judgment.
As in art, classic audio components are the results of individual efforts and reflect a coherent
underlying philosophy. They make a subjective and an objective statement of quality which is
meant to be appreciated. It is essential that the circuitry of an audio component reflects a
philosophy which address the subjective nature of its performance first and foremost.
Содержание Pass Aleph 60
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