所以我今早就睇左呢篇野 :
The PLH Amplifier By Nelson Pass
Introduction: The JLH Amplifier
In 1969 John Linsley-Hood wrote in Wireless World:
During the past few years a number of excellent designs have been published for
domestic audio amplifiers. However, some of these designs are now rendered
obsolescent by changes in the availability of components, and others are intended to
provide levels of power output, which are in excess of the requirements of a normal living
room. Also, most designs have tended to be rather complex.
In the circumstances it seemed worthwhile to consider just how simple a design could be
made which would give adequate output power together with a standard of performance,
which was beyond reproach, and this study has resulted in the present design.
He then described a Class A power amplifier using three gain stages of bipolar transistors in a
topology, which continues to be admired for its elegant simplicity and sound quality.
The centerpiece of this design is the middle stage, an NPN transistor used as a phase splitter,
simultaneously driving the positive half of the output stage and the negative half with symmetric
signals of opposite phase.
Figure 1 shows a simplified version of the JLH topology. Signal input appears at the Base of
Q1, and is amplified and inverted to drive the Base of Q2. Q2 acts as a gain device and also a
signal splitter, driving both Q3 and Q4 simultaneously, but out of phase with each other. Q3 and
Q4 form the output transistors, Q3 operating as a Common Emitter gain device, contributing
current and voltage gain, and Q4 operating as a Common Collector device contributing only
current gain. The resistors provide bias for the system, and R1 and R2 feed the output of the
amplifier in a loop back to the emitter of Q1.
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樓主
發表於 2012-5-18 13:04
:
好旗袋......
91 sensitivity.....不過幫主你個對好似過百...
我好鍾意1100架...
