Pass Labs XA60 ユーザーズマニュアル

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XA60 Owner’s Manual
Analog designer Nelson Pass has over the years produced some 
truly great solid-state amplifiers, each unique in it’s own way.  Not 
surprisingly, the Pass Laboratories™ XA60 monoblock amplifier 
is no exception. The XA60’s sleek industrial design is a stunning 
understatement of  artistic form integrated with state of  the art 
function.
Since their introduction in 1997, the X amplifier series using the 
patented Supersymmetry™ circuit topology have been the mainstay 
of  amplifier offerings from Pass Laboratories™.  These amplifiers 
are heavily biased Class A/B designs with only two gain stages and 
an absolutely minimal component count in the signal path.  In spite 
of  this simplicity and thanks to the unique characteristic of  the X 
topology, these amplifiers achieve very high power with outstanding 
subjective and objective performance.
With the introduction of  the XA60 Pass Laboratories™ significantly 
raises the performance standard of  excellence by introducing an 
entirely new series of  power amplifiers.  The new “XA” series of  
amplifiers feature a refined and elegantly simple, very highly biased, 
pure Class A mode of  operation.  This is a new and unique circuit 
topology that we descriptively characterize as being Single-ended 
Class A. This new topology combines the very best characteristics of  
Pass Laboratories™ “X” series amplifiers and the highly rated “Pass 
Laboratories Aleph™”.  The XA series is the marriage of  a highly 
refined Aleph™ output stage with the patented Supersymmetry™ 
“X” front end.
The emphasis of  the XA series is to accentuate performance and 
sonic refinement over power.  The XA series has the characteristic 
warm midrange and sweet top end of  the Aleph™ product 
conjoined with the extreme dynamic range and definitive bass 
control of  the X series amplifiers.
The XA60 is packaged in an artistically refined variant of  the massive 
chassis previously reserved for the 150 watt X-150.5 two channel 
stereo amplifier, but running more than twice the Class A bias 
current of  our A/B amplifiers. 
 The Pass Laboratories™ XA60 will deliver 60 watts rms into 8 
ohms of  impedance.  This is the amplifiers class A limit, driving 
the XA60 harder or reducing the impedance of  the load will not 
convey any additional power. Driving into a short will not convey 
any additional power. These are not design oversights or flaws in 
the XA60, but rather a condition of  the very highly biased Class A 
operation.  However; as an interesting point of  reference, 60 watts 
driving a 87dB/1W/1m speaker will deliver well in excess of  100 dB 
Introduction