Sony STR-DA1000ES ES Receivers Technical Background - Page 4

A look at analog amplifiers 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 Page 4