Pass Labs X5 User Manual

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TM

May 18, 2006

X5 Owner’s Manual

X5 Owner’s Manual

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Introduction

The X5 five channel amplifier embodies the design technology and
refinements of the larger “X” series amplifiers including extensions
of the patented Supersymmetry circuit.

The Supersymmetry circuit topology was granted a U.S. patent in
1994, and is the result of 19 years of effort by Nelson Pass. The
amplifier uses highly matched components in a classically simple
balanced Class A circuit. The amplifier contains only two simple
stages: the first is a balanced single-ended Class A voltage gain stage.
Its output drives a bank of high power Mosfets operated as voltage
followers.

These are inherently low distortion types of circuits, but their
performance is improved when operated in balanced mode through
cancellation. Distortion and noise identical to both halves of a
balanced circuit will disappear at the output, and in a well-matched
symmetric circuit, most of the distortion and noise is identical.

Supersymmetry enhances this effect by providing a connection
between the two halves of the balanced circuit that further perfects
the match. Any distortion and noise not already identical to the two
halves is made identical, and the result is improved cancellation at the
output.

Unlike feedback techniques where the goal is to correct for the
distortion by feeding a gain stage an inversely distorted signal,
Supersymmetry seeks merely to create perfect matching.

Matched balanced power circuitry typically sees a distortion
and noise reduction of about 90% (20 dB) through a balanced
connection without any additional effort. The Supersymmetric
circuit delivers another 90% reduction, so that the X series has
about 1/100 of the distortion of a conventionally simple amplifier.
Actually this ordinary distortion and noise can still be seen at the
output of one half of the circuit, but since it is virtually identical
on the other half, it goes away at the speaker terminals. This gives
good measured performance, which because it is simple, also sounds
excellent.

Previously these kinds of simple Class A circuits have been popular
for their sound quality in low power amplifiers, but have not found
application at high power levels due to excessive distortion and low
efficiency. Supersymmetry overcomes this barrier, delivering the
sweetness, staging, and detail of very simple circuitry up to kilowatt
power levels and beyond.

X5 Owner’s Manual

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The X Series amplifiers have the tremendous dynamic range (>150
dB) to do justice to the 24 bit recordings of the 21st Century. The
simple but powerful circuitry moves easily from total silence to
explosive transient and back to silence without a trace. It’s a spooky
experience.

So relax and enjoy your amplifier. Call us if you ever have a problem
or question. Thank you for buying our product.

Setup

You can position the amplifier anywhere you want, but it requires
ventilation. We do not recommend placing it in enclosed cabinets or
small closets without means for air to circulate freely. The amplifier
idles at about 200 watts.

Let’s talk about power requirements. The amplifier draws about
2 amps (continuous rms) out of the wall during normal audio
operation, and this reflects mostly the idle current that we run
through the output stage. If you are driving a low impedance load,
you will draw more than this, but this will not be typical.

The X5 is provided with the more conventional AC line cord, which
is rated at 15 amps. The circuit ground is attached to the chassis in
the conventional manner.

Under no circumstances should you defeat the ground connection of
the power cord. For your safety, the chassis of the amplifier should
be earth grounded.

Looking at the rear panel you will see the AC power cord receptacle,
a power switch, fuse holder, five pairs of output connectors, a pair of
5 way connectors for remote turn-on, five RCA input connectors and
five XLR balanced input connectors.

X5 Owner’s Manual

Make sure that the power switch is off (down). Plug the AC cord
into the back of the amplifier, and then into the wall. Then turn the
switch on (up). The lights in your house will blink when the power
supply charges the capacitors.

On the front panel, the “Standby” LED indicator should be glowing
blue, indicating that the power is on. The “Power” LED should
not be on. If the “Power” LED is on, don’t get excited, just use
the front panel stand-by button to go to stand-by mode, with the
“Standby” LED on and the “Power “ LED off.

OK, so the amplifier is sitting there in stand-by mode with just the

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