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Pass Labs Two-Chassis, Dual-Monaural Xs Series Preamplifier

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Pass Labs Xs Series Preamplifier

New Flagship Preamp, Matched for the Xs-300 and Xs-150 Amps, Delivers Superb Performance & Ultra Low Noise Via Advanced Electronic Design & Materials

Nov. 6th, 2013 — Pass Laboratories, Inc., an audio innovator renowned for its unique high-performance products, has announced it is beginning shipments this month of its Xs Preamplifier, designed by Wayne Colburn, and the new flagship of its preamplifier line. The Xs Preamp is entirely new and designed to complement the ultimate performance standards of Pass Labs’ new and highly regarded, dual-chassis Xs-300 and Xs-150 Amplifiers.

Each circuit board in the dual chassis of Pass Labs’ new two-channel Xs Preamplifier has been optimized through an arduous trial-and-error listening process designed to obtain top performance in each functional area for which a board is employed. Custom designed for the ultimate in music listening, the Xs Preamp opens up the soundstage, delivers a greater sense of space and layering, and provides a clearer window into the performance of reproduced music. It achieves a frequency response of -3dB at 2 Hz and 60 kHz, and a signal-to-noise ratio of -110 dB. Equally important, it applies numerous lessons Pass Labs learned designing its breakthrough XP-30 3-Chassis Reference Preamplifier, and the two Xs Series Amplifiers.

The Xs Preamp features for each channel separate low-noise power supplies that employ 100,000-microfarad capacitors and new silicon carbide semiconductors to achieve low noise and high performance. The Xs Preamp is quieter than the XP-30 and has an even more improved power supply. In appearance, it resembles the Xs Amplifiers and features two large chassis built with a true dual-monaural topology. Internally, it has been innovatively designed, especially in its use of high-quality materials.

Pass Labs fabricated its circuit boards from materials sourced in many cases from the military and high-speed computer sectors for their superior performance. Pass Labs also optimized each circuit board through an arduous trial-and-error listening process designed to obtain top performance in each functional area for which a board is employed. For example, circuit boards for power supply circuits have different requirements than ones for gain stages. In the Xs Preamp, each board is optimized for its specific use.

Each of the Xs Preamp’s two channels has its own power supply board, both featuring an optimized circuit design and layout. The boards’ 100,000-microfarad (uF) capacitors are optimized for low noise and high performance through the use of a variety of materials, from highly reliable electrolytics to a custom polypropylene. Innovatively utilizing newly available silicon carbide semiconductors further heighten performance by dropping noise below the level of Pass Labs own remarkable XP-30 Preamp.

The Xs Preamp’s Class-A gain stage circuitry, the preamp’s electronic heart, harnesses a direct-coupled, ultra- symmetric gain path and auto-bias to maximize and sustain its sonic impact. The circuit boards for the gain stages have been completely redesigned for maximum sonic impact. They employ a direct-coupled (DC), ultra-symmetric gain path with high-bias Class-A circuitry, and feature auto bias and DC-compensation to maintain peak performance. An extra large, high-definition display addresses listeners’ desire to know a music system’s status even from across a brightly lit room. The 20-character display is easy to read, turn on or off and dim. The Xs Preamp comes supplied with a remote control. Its rear panel includes six single-ended, balanced inputs, including a pass-through, a tape loop, and dual-power input connections. It also provides two fixed and one variable output, both of which are single-ended, balanced and suitable for bi-amping. The preamp’s two chassis weigh a total of 80 pounds, with each chassis measuring 19 inches wide by 14 inches deep by 6.25 inches high.

The Xs Preamplifier will be available this month from authorized Pass Labs dealers at a suggested price of $38,000 (MSRP).

Pass Labs Xs Series Preamplifier Power Supplies

Pass Labs Xs Series Preamplifier Power Supplies Top View


The Xs Preamp’s Class-A gain stage circuitry, the preamp’s electronic heart, harnesses a direct-coupled, ultra-symmetric gain path and auto-bias to maximize and sustain its sonic impact.

About Pass Labs
Founded in 1991 by legendary audio designer Nelson Pass, Pass Laboratories, Inc. markets its unique amplifiers, preamplifiers and speakers throughout the world. The company has been based in and manufacturers in Foresthill, California, since its beginning, and is widely regarded as one of the most innovative audio brands in the world. Its critically acclaimed Aleph, X and XA-Series products have won numerous awards, and Founder Nelson Pass holds numerous audio patents. His achievements include developing the first dynamically biased Class-A amplifier circuit, developing a fully cascode audio power amplifier, and developing the Stasis amplifier in 1977. He helped popularize solid-state, single-ended Class-A power amplifiers, and developed the very successful Aleph series of products, and the Super-Symmetry™ circuit, which achieves exceptionally low distortion and noise levels.
For further technical information, visit Pass Labs’ website at

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