Few fields of technical endeavour are more plagued with errors, mis-statements and confusion than audio. In the last 20 years, the rise of controversial and non-rational audio hypotheses, gathered under the title Subjectivism has deepened these difficulties.
It is commonplace for hi-fi reviewers to claim that they have perceived subtle audio differences which cannot be related to electrical performance measurements.
These claims include the alleged production of a ‘three-dimensional sound-stage and protests that the rhythm of the music has been altered’; these statements are typically produced in isolation, with no attempt made to correlate them to objective test results. The latter in particular appears to be a quite impossible claim.
This volume does not address the implementation of Subjectivist notions, but confines itself to the measurable, the rational, and the repeatable. This is not as restrictive as it may appear; there is nothing to prevent you using the methodology presented here to design an amplifier that is technically excellent, and then gilding the lily by using whatever brands of expensive resistor or capacitor are currently fashionable, and doing the internal wiring with cable that costs more per metre than the rest of the unit put together.
Such nods to Subjectivist convention are unlikely to damage the real performance; this is however not the case with some of the more damaging hypotheses, such as the claim that negative feedback is inherently harmful. Reduce the feedback factor and you will degrade the real-life operation of almost any design.
Such problems arise because audio electronics is a more technically complex subject than it at first appears. It is easy to cobble together some sort of power amplifier that works, and this can give people an altogether exaggerated view of how deeply they understand what they have created.
In contrast, no-one is likely to take a ‘subjective’ approach to the design of an aeroplane wing or a rocket engine; the margins for error are rather smaller, and the consequences of malfunction somewhat more serious.
The Subjectivist position is of no help to anyone hoping to design a good power amplifier. However, it promises to be with us for some further time yet, and it is appropriate to review it here and show why it need not be considered at the design stage. The marketing stage is of course another matter.
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