Sony STR-DA1000ES Technical Background page 4

Conventional, analog power amplifiers have awkward characteristics that
are so familiar that receiver engineers automatically work around them.
However, Sony's design program for the 2003 ES Series required more than the
typical work-around. We sought to address these issues directly:
• Circuit complexity. In the context of today's home theater receivers, the
analog power amplifier is out of place. You have digital source material
processed through a digital preamplifier—only to be converted to analog prior
to amplification.
• Heat generation. The heat thrown off by conventional power output
transistors is a central fact of amplifier and receiver design. Conventional
amplifiers and receivers often require heat sinks, fans, and chassis layouts
that isolate the output transistors at the back or sides. Heat is always bad for
electronics. Sony sought a more comprehensive solution for these ES
receivers.
• Crossover distortion. Conventional power amplifiers use complementary
pairs or sets of transistors to handle the top half and the bottom half of the
waveform. This can create crossover distortion, the solution to which is
amplifier bias—and that means more heat!
• Thermal modulation distortion. As the changing audio signal passes
through the typical output transistors, it causes immediate changes in the
transistors' temperature. Unfortunately, the temperature changes affect the
transistors' handling of audio signal. This is thermal modulation distortion.
Left unchecked, it can degrade sound quality.
• Open-loop distortion. Conventional amplifiers typically generate substantial
distortion in "open-loop" mode. That's why amplifiers correct this distortion
with Negative Feedback (NFB). However, NFB exposes the signal to
Transient Intermodulation Distortion and other dynamic problems.
Sony's design program for the 2003 ES receiver line overcomes these
fundamental constraints by applying digital technology.
S-Master Pro: simplicity of design
For years, it's been evident that digital power amplifiers can solve many of
the intrinsic problems of analog amps. But now, digital amplifiers have the sound
quality and technical performance to meet the stringent requirements of Sony ES
engineers. The S-Master Pro design draws on 1-bit technologies that Sony
originally developed for the Super Audio Compact Disc. The result is a
breakthrough in home theater component design.
ES Receivers V3.0
A look at analog amplifiers
Page 4