Introduction

X1000.5 Owners Manual

The Pass Laboratories ™ X1000.5 stereo amplifier embodies the de- sign technology and refinements of the “X” series amplifiers includ- ing extensions of the patented Supersymmetry™ circuit. Additionally selected refinements of the XA series amplifiers have been incorpo- rated into the X1000.5 to significantly improve this products sonic performance in comparison to it’s immediate predecessor, the Pass Laboratories™ X1000.

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 perfor- mance 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 provid- ing a connection between the two halves of the balanced circuit that further perfects the match of common mode artifacts. Any distor- tion 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 distor- tion by feeding a gain stage an inversely distorted signal, Supersymme- try™ 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 ampli- fier. 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 un- desirable artifacts largely go away at the speaker terminals. This gives good measured performance, and because a simple circuit produces it, also sounds quiet excellent.

X1000.5 specifications

Pass Labs X1000.5 is a high-performance power amplifier that has earned a stellar reputation among audiophiles and sound engineers alike for its exceptional sound quality and robust design. Created by renowned audio engineer Nelson Pass, the X1000.5 exemplifies the fundamental principles of Pass Labs: simplicity, purity, and musicality.

At the core of the X1000.5's capabilities is its Class A operation, delivering 1000 watts of power into 8 ohms and effectively doubling that into 4 ohms. This Class A architecture ensures minimal distortion and a linear response, allowing for an incredibly accurate reproduction of sound across the entire frequency spectrum. The soundstage is wide and immersive, enabling listeners to discern subtle details in both music and vocal performances.

One of the standout technologies employed in the X1000.5 is the use of a complementary output stage consisting of high-speed MOSFETs. This allows the amplifier to manage high instantaneous current demands without sacrificing control or transparency. The use of MOSFETs also contributes to a warm and engaging sonic signature that is characteristic of Pass Labs' designs. The amplifier’s circuitry is designed with an emphasis on low negative feedback, which further enhances the natural sound quality.

The build quality of the X1000.5 is equally impressive. Housed in a robust chassis designed to minimize resonance and electromagnetic interference, the amplifier features a dual-mono configuration with separate power supplies for each channel. This not only provides ample power but also ensures channel separation and coherence in sound reproduction. It also incorporates high-quality components such as low ESR capacitors and a custom-made toroidal transformer, which contributes to its excellent performance.

Additional features include an easy-to-use input stage that supports both balanced XLR and single-ended RCA connections, making it compatible with a wide range of source components and speaker systems. The X1000.5 is also equipped with protection circuitry that prevents over-temperature and over-current situations, safeguarding both the amplifier and connected speakers.

In summary, the Pass Labs X1000.5 is a masterful blend of power, precision, and artistry. With its Class A operation, advanced MOSFET technology, solid build quality, and user-friendly features, this amplifier is a compelling choice for audiophiles seeking to elevate their listening experience to new heights.