Pass Labs Car Amplifier XA60 ユーザーズマニュアル

XA60 Owner’s Manual

The amplifier has only the two stages, an input stage of a balanced pair of

input devices, and the output stage, a balanced pair of single-ended Class

A power Mosfets. Like the Aleph™, you can trace a path from input to

output through only two gain devices. Like the X amps, feedback is used

only to set the gain and correct for dissimilarities between the two matched

output stages.

There are no adjustments. There are no frequency compensation capaci-

tors. The amplifiers are unconditionally stable and reliable into any load.

They are not fragile, temperamental or prone to failure.

The XA amplifiers operate at approximately 33% efficiency, which is to

say they idle at three times their rated output. The XA200 is rated at 200

watts output into 8 ohms and draws something over 600 watts of AC

power. This design is an exercise in highly conservative engineering, which

provides exceptional reliability and product longevity. The output devices

are exposed to no more than a fraction of the voltage and wattage they are

designed to endure.

These rugged power devices are matched to about .3% and mounted on

Mica insulators. Their massive heat sinks run at about 25 degrees C. above

ambient temperature, so that actual chip temperatures are about 70 degrees

below their rating. The output devices are designed to last a very long time

under these conditions, with a probable life of about 50,000 hours.

The power supply of the XA 200 uses elaborate RF filtering and noise sup-

pression designed to block AC noise and line DC. The substantial toroidal

power transformer is followed by high speed rectifiers, and significant uF

of computer grade capacitors in a passive filter arrangement. In addition

to a main power switch the amplifier has a standby mode, which shuts

down the bias to the circuit while keeping the supply active, significantly

extending the life of the filter capacitors.

The sound of the XA amplifiers is a quantum leap over the parents. They

retain the sweet warmth and lushness of the Aleph™ series without the

fluffy coloration’s. The dynamic contrast is even better than the X series;

transients leaping from black to crescendo and back again with no tele-

graphing or hangover.

The bass has as much control over the speaker as the original X amps, but

is a bit more neutral and carries subtler nuance. The midrange is a little

deeper and the soundstage wider than the Alephs™.

Are the XA’s better than Alephs™ and X’s in every respect?

Yes, except for the higher power/current ratings of the X amps.

Are they the best audio amplifiers that money can buy? Absolutely!