| 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.
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.
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 single-stage 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.
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 X1000 is provided with a special high current 20 amp power cord that
is not like 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 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.
Also like the X1000, the X600 only accepts balanced inputs.
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 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. |
