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分立件做好了,确实不容易。
我想你一定听说当今国际音响界大腕,John Curl。他设计岀不少当今还在流行的放大器,冠以JC-2, JC-1…等代号的那位。近日他在一国际DIY网坛与朋友也正在讨论相关的话题。我将他今天的有关论述帖上,供参考:
JC:Now, what is the 'advantage' of this sort of circuit over a good IC, especially at the time that it was first used? (1977)
First, the circuit has to operate Class A, so it removes any crossover distortion.
Second, the circuit is fast, perhaps 50-100V/uS, because the additional compensation is minimum, to make it stable.
Third, it can be very quiet, especially with the later offered Toshiba jfet pairs.
Fourth, it has a MINIMUM thru-path between input and output, and virtually no input bias current.
etc.
Now, what are its limitations? Without a cascode on the input stage, the design works best between +/- 15V to 20V.
The device CANNOT drive a 600 ohm load, because the peak current only 5 ma or so, and the open loop gain will drop drastically with a load less than 2K ohm or so.
The layout takes somewhat more room than a typical op amp.
Still, this is one of the best 'compromises' that I have come across, and properly utilized, it will sonically 'beat' just about every IC op amp that is out there.
我最㸝赏的是他几十年如一日地全心至力于消除音响通道上的所有耦合电容的电路设计。
。他的一张35年前的旧电路图。 |
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