Pass Labs - XA100.5 100 watt Class A Mono Block Amplifier/ pair

Pass Labs



Product No.:
M XA100
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Analog designer Nelson Pass has over the years produced some truly great solid-state amplifiers, each unique in its own way. Not surprisingly, the Pass Laboratories XA100.5 monoblock amplifier is no exception. The XA100.5's sleek industrial design in 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 characteristics of the X topology, these amplifiers achieve very high power with outstanding subjective and objective performance.

With the introduction of the XA100.5 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 Pass descriptively characterizes 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 XA100.5 will deliver 100 watts rms into 8 ohms of impedance. This is the amplifier's Class A limit, driving the XA100.5 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 XA100.5, 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 105 dB (quite loud) average acoustic signal in a 100 cubic meter room.


Gain 26dB
Freq. Response -3 dB at 1.5 Hz, -3 dB at 100 kHz
Power Output 100 watts max @ 1% THD, 1 kHz, 8 ohms
Distortion 0.05% @ 10 W, 1% @ 100 W @ 1 KHz approx.
Output Voltage Maximum plus, minus approx. 40 volts
Output Current Maximum plus, minus approx. 5 amps
Input Impedance 22 kohm balanced, 11 kohm unbalanced
Damping factor 30 ref 8 ohms nominal
Slew rate approx. plus, minus 50 V/uS
Output Noise approx. 300 uV unweighted 20-20 kHz
Random noise floor approximately 2 uV
Dynamic range 154 dB (random noise floor to peak output)
Balanced CMRR approx. -60 dB @ 1 kHz (input common mode rejection ratio)
DC offset < 100 mv
Power Consumption approx. 300 watts
Dimensions 19"W x 9.5"H x 22"D
Weight 100

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