Introduction

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