Pass Labs X600.5 User Manual

pass

TM

May 17, 2006

X600.5 Owners Manual

X600.5 Owner’s Manual

1

Introduction

The Pass Laboratories ™ X600.5 stereo amplifier embodies the de­sign technology and refinements of the “X” series amplifiers includ­ing extensions of the patented Supersymmetry™ circuit. Additionally
selected refinements of the XA series amplifiers have been incorpo­rated into the X600.5 to significantly improve this products sonic
performance in comparison to it’s immediate predecessor, the Pass
Laboratories™ X600.

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

These are inherently low distortion types of circuits, but their perfor­mance is significantly improved when operated as balanced devices.
Distortion and noise identical to both halves of a balanced circuit can
be made to disappear at the output, and in a well-matched symmetric
circuit, most of the distortion and noise is identical.

Pass Laboratories Supersymmetry™ enhances this effect by provid­ing a connection between the two halves of the balanced circuit that
further perfects the match of common mode artifacts. Any distor­tion and noise not already identical to the two halves is made more
identical by a factor of about 10. The result of this perfected match
is improved noise cancellation at the output of the amplifier. From a
listeners standpoint this results in a more accurate presentation of the
soundstage and better resolution of low level detail.

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 between the two halves
of an otherwise well matched circuit.

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 Supersymmetry™ circuit delivers
another 90% reduction, so that the X series has about 1/100 of the
distortion of a conventionally simple and otherwise identical ampli­fier. 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, these un­desirable artifacts largely go away at the speaker terminals. This gives
good measured performance, and because a simple circuit produces it,
also sounds quiet excellent.

X600.5 Owners Manual

2

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.

The X.5 Series amplifiers have the tremendous dynamic range (>140
dB) to do justice to the high-resolution digital recordings of the 21st
Century and the elegance to retrieve the micro dynamics offered by
the most sensitive loudspeakers. The simple but powerful circuitry
moves easily from total silence to explosive transient and back to
silence without a trace and without information loss. Very unlike
conventional high power amplifiers, they provide this level of power
with a subtlety befitting some of the better tube amplifiers. This per­formance is consistence across the audio spectrum and the amplifiers
are unconditionally stable into all speaker loads.

So relax and enjoy your amplifier. Call us if you ever have a problem
or question. You are welcome to ask questions or offer comments.
Thank you for buying our product.

X600.5 Owners Manual

3

Setup

You can position this amplifier most anywhere you wish, but it re­quires adequate ventilation. We do not recommend placing it in
enclosed cabinets or small closets without means for air to circulate
freely. Stacking these power amplifiers directly upon each other is not
recommended for the same reason. This amplifier idles at about 550
watts, most of which dissipates as heat across the heatsinks. As a point
of reference, these heatsinks should never become too hot to touch
for several seconds.

Let’s talk about AC power requirements. This amplifier draws about
5 amps (continuous rms) at 120 volts out of the wall during normal
operation, and this power draw reflects mostly the idle current that
we run through the output stage. If you are driving a low impedance
load, you will draw more power than this, but this will not be typical.

The amplifier’s voltage and current rating are indicated on the rear
panel. It will be 240 volts, 220 volts, 120 volts or 100 volts, all with
an appropriate rear mounted resetable circuit breaker. The frequency
rating of the AC line source in all instances will be 50 to 60 Hz. Please
verify that the amplifiers indicated voltage requirements are consistent
with the line voltage supplied at your location.

The Pass Laboratories™ X600.5 is provided with a conventional IEC
detachable AC line cord, which is rated at 15 amps. The safety ground
is attached to the chassis in the conventional approved manner. The
AC power input to the amplifier runs through a RF filter, which re­moves high frequency noise coming into and going out of the ampli­fier power supply.

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. Signal ground is isolated from chassis, safety ground,
to reduce the incidence of ground loop noise. The presence of a
safety ground will not degrade the audio signal chain.

You may substitute an aftermarket detachable IEC 320 style power
cord of your choosing; provided it is rated for at least 15 amps and it
meets all legal requirements and has been approved by the local testing
authority for such things.

Looking at the rear panel you will see the IEC 320 AC power cord
receptacle, a thermal magnetic breaker switch, two pairs of output
connectors, a pair of binding post connectors for remote turn-on, one
RCA input connector and one XLR balanced input connector.

X600.5 Owners Manual

Make sure that the breaker switch is off (down). Plug the AC cord

4