Sony har nå gått tilbake fra s-master til gamle måten på både hifi og surround.
Årsaken var at prisen på surround forsterkerne var for dyre og på hifi fikk de dårlig respons fra kundene.
Her er Sony sin argumentasjon for s-master / pwm konstruksjon klippet fra:
https://docs.sony.com/release/ES_STR_05_Final.pdf.
Why Digital Amplification? After decades of engineering practice, the limitations and awkwardcharacteristics of traditional amplifiers have become so familiar that mostengineers don't even notice them:
• Complexity. In the context of today's home theater receivers, you havedigital source material processed through a digital preamplifier—only to beconverted to analog prior to amplification.
• Heat generation. Conventional power output transistors throw off much oftheir power as heat. And heat is always bad for electronics.
• Thermal modulation distortion. Changes in the audio signal cause immediate changes in the output transistor temperature, which in turn causechanges in transistor performance! This is thermal modulation distortion.
• Crossover distortion. Conventional transistor pairs create crossoverdistortion, which becomes particularly audible during quiet passages. Thenormal solution is amplifier bias—which means more heat!
• Open-loop distortion. Traditional amplifiers typically generate substantial"open-loop" distortion. The Negative Feedback (NFB) used to correct thiscan trigger other problems like Transient Intermodulation Distortion.
Commonly understood for decades, these limitations are so thoroughlyingrained in home audio design that they're considered "inevitable." Resolvingthese issues means accepting massive heat sinks, tolerating circuitous signalpaths and chasing down transient distortions. ... Digital amplifiers had been around for decades, outside the mainstream ofhome audio. But great strides in Large Scale Integration (LSI), 1-bit processingand faster MOS FET output transistors have opened the door to a new generation of digital amplifier technology.
Her er en artikkel om mannen bak Sony sine topp serier fra 90 tallet og utviklingen av pwm modellene.
The "mad scientist" of Sony audio | Sound & Vision
Teknologien har gjort at man nå kan lage klasse-d bedre enn før.