| Цитата |
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| цитату Bruce Candy: "I am convinced that the major cause of the harsh sound from transistor power amplifiers arises from the power output stage. This seems to be due to the particular nature of non-linearities exhibited by transistors. In particular transistors are acutely non-linear near current turn-off points and low voltages which these devices experience during large signal transients. Valves simply do not exhibit this acute behaviour. However, it is also well established that power FET amplifiers are capable of sonic improvements over BJT based power amplifiers. This is despite the fact that BJT power output stages intrinsically are capable of producing lower measured distortion than FETs. This extensively has been high-lighted by the well known author Douglas Self. There is an excellent example of measurements disagreeing with sonics! However CAREFULL!! analysis reveals that FETs are quite definitely less pronounced than BJTs in non-linear transients that occur when current is transferred between the "pull-down" and "pull-up" devices. This seems to be the main offending cause for this difference, particularly at high frequencies. Hence the term "harsh" is useful in describing transistor sound, particularly BJT output stage based sonics. Furthermore, even though lateral structure FETs measure less non-linear behaviour than vertical structure devices in most respects, again CAREFULL!! analysis clearly shows that the reverse is true for a few other parameters. Yet again, this difference is most acute in the transients that occur when current is transferred between the "pull-down" and "pull-up" devices. As a result, the Halcro amplifiers are unusual in that they employ vertical structure power FETs. These together with circuitry which cancels the said acute non-linearities of the output stage, results in the Halcro amplifier output stages producing non-linearities several orders of magnitude less than standard circuits. This seems to main reason why the Halcro amplifiers do not exhibit that harshness associated with solid state amplifiers. " |
--- если вкратце - то речь идет об особой линейности полевиков?... и это и есть преимущества над биполярниками?
... и только при тщательном "вслушивании" у меня появляются глюки на предмет того что сд702 - "звучит" чуточку лучше...на такую чуточку что я не стал бы зарубаться на спор со слепым тестом...