PassLabs X Brochure

THE LEADER IN AMPLIFIER TECHNOLOGY

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.

The X Series are the biggest and most powerful amplifiers
we have ever created, but they are not unique for that reason.
We have chosen the biggest and most powerful as the proper
temple for a new concept in high performance audio amplifica­tion.

Called Supersymmetry™, the circuit topology was granted a
U.S. patent in 1994, and is the result of 19 years of effort by
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 without feedback.

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.

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 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.

Because these amplifiers do not rely on output feedback
for high performance, their performance is consistent
across the audio band, from DC to beyond audibility. They
are unconditionally stable into any loudspeaker.

The X1000 mono block has only two gain stages: a single­stage front end which provides all of the voltage gain, and
a high current follower stage.

The output follower stage consists of four massive banks
totaling 80 power Mosfets, aggregately rated at 12 kilowatts
and biased for class A operation to 128 watts peak. Beyond
the bias point, the output stage operates Class AB. The
bias current is set for 600 watts idle dissipation per chan­nel.

The power supply features two massive toroidal transform­ers at 4 KVA, parallel high current rectifiers, and 250,000
uF of storage at over 700 Joules.

PASS LABS

most of the ones you are used to. It is heavier,
and mates to a standard receptacle at the rear
of the amplifier. This power cord requires a
high current wall socket.

The X600 utilizes the same face plate, meter,
and front end circuitry as in the larger X1000.
It has a proportionately smaller power supply
and output stage.

The X350 is a stereo amplifier housed in
the same chassis as the X600 mono block,
utilizing the same face plate, meter, and
power supply as the X600. Like the larger
mono block models the X350 does not rely
on output feedback for high performance
and its performance is consistent across
the audio band, from DC to beyond audi­bility. It is unconditionally stable into any
loudspeaker.

The input and output of the amplifier
is direct coupled, and the amplifier only
accepts a balanced input. This is the first
amplifier that truly demands balanced oper­ation to obtain the highest performance.

For higher power operation, X1000’s can be
operated in an array producing up to 2000
watts per chassis. For example, two X1000’s
can deliver 4000 watts into 8 ohms or 2
ohms. Four X1000’s can deliver 8000 watts
into 4 ohms, and sixteen X1000’s can deliver
32,000 watts into 1 ohm. Unlike previous
efforts at harnessing multiple amplifiers
through power transformers, the amplifiers
are direct-coupled to the load, and retain the
same performance across the audio band
without added distortion and loss.

The meter on the face plate of the X1000
measures the current drawn by the output
stage. At idle, it sits slightly less than full
scale, reflecting the standing bias current of
Class A operation. As the amplifier exceeds
its class “A” rating the needle on the ampli­fier will register the increased bias being
drawn by the output stage.

The output follower stage consists of 48
power Mosfets per channel for a total of over
7200 watts short term dissipation. The power
supply features a single massive toroidal trans­formers rated at 4 KVA, and over 180,000 uF
of storage capacitance.

Like the meter on the X1000, the X600 meter
measures the current drawn by the output
stage. At idle, it sits at half scale, reflecting
the standing bias current of Class A opera­tion. As the amplifier exceeds its class “A”
rating the needle on the amplifier will register
the increased bias being drawn by the output
stage.

The output follower stage consists of 24
power Mosfets per channel for a total of
over 3600 watts short term dissipation per
channel. The bias current is set for about
500 watts idle dissipation between both
channels.

The input and output of the amplifier is
direct-coupled, and the amplifier accepts
both single-ended and balanced inputs.

The meter on the face plate of the X350
measures the total current draw of both
amplifier channels. At idle, the meter sits
at about half scale, reflecting the standing
bias current. As the amplifier draw exceeds
exceeds Class “A” operation the needle on
the amplifier will register the increased cur­rent being drawn by the power supply.

The X1000 is provided with a special high
current 20 amp power cord that is not like

X1000 X600 X350Specifications

Gain
Freq. Response
Power Output
Max Output Voltage
Max Output Current
Input Impedance
Damping factor
Slew rate
Output Noise
Random noise floor
Dynamic range
Balanced CMRR
DC offset
Power Consumption
Temperature
Dimensions
Shipping Weight

30 dB

-0 dB at DC, -3 dB at 60 kHz
1000 watts @ 1% THD, 1 kHz
plus, minus 145 volts
plus, minus 30 amps
22 kohm balanced
60 ref 8 ohms nominal
plus, minus 40 V/uS
500 uV unweighted 20-20 kHz
approximately 2 uV
155 dB

-85 dB @ 1 kHz
< 100 mv
600 watts idle, 2400 watts max
20 degrees C. above ambient
19 “ W x 28” D x 11.5” H
200 lbs.

Pass Labs, PO Box 219, Foresthill, CA 95631, Tel: [phone], Fax: [phone], www.passlabs.com

Also like the X1000, the X600 only accepts
balanced inputs.

30 dB

-0 dB at DC, -3 dB at 100 kHz
600 watts max @ 1% THD, 1 kHz
plus, minus 105 volts
plus, minus 25 amps
22 kohm balanced
60 ref 8 ohms nominal
plus, minus 50 V/uS
500 uV unweighted 20-20 kHz
approximately 2 uV
153 dB

-85 dB @ 1 kHz
< 100 mv
600 watts idle, 1800 watts max
20 degrees C. above ambient
19 “ W x 22” D x 11.5” H
150 lbs.

28 dB

-0 dB at DC, -4 dB at 100 kHz
350 watts max@ 1% THD, 1 kHz
plus, minus 80 volts
plus, minus 20 amps
22 kohm balanced
30 ref 8 ohms nominal
plus, minus 50 V/uS
500 uV unweighted 20-20 kHz
approximately 2 uV
150 dB

-85 dB @ 1 kHz
< 100 mv
600 watts idle, 1800 watts max
20 degrees C. above ambient
19 “ W x 22” D x 11.5” H
150 lbs.