Pass Labs XA100 - Manual (Page 2)

2 XA100 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 ™ XA100 monoblock amplifier
is no exception. The XA100’s sleek industrial design is a stunning
understatement of artistic form integrated with state of the art
function.
Since the 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 XA100 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 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 XA100 is packaged in an artistically refined variant of the
massive chassis previously reserved for the 250 watt X-250.5 stereo
amplifier, but running more than twice the Class A bias current of
our other amplifiers.
The Pass Laboratories™ XA100 will deliver 100 watts rms into
8 ohms of impedance. This is the amplifiers class A limit, driving
the XA100 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 XA100, but rather a condition of the very highly biased Class A
operation. However; as an interesting point of reference, 100 watts
driving a 87dB/1W/1m speaker will deliver in excess of 105 dB
(quite loud) average acoustic signal in a 100 cubic meter room.
Introduction