Aleph Single-Ended Class A

The Supersymmetery Aleph™

XA200 Owner’s Manual

they vanish at the output, typically by a factor of 10 or so for matched single-ended Class A circuits.

Supersymmetry™ extends this concept by using feedback only to make the distortion and noise more identical on each half of a balanced cir- cuit, not to eliminate it as such. This gives as much as a 100:1 reduc- tion in unwanted distortion and noise without requiring the equivalent amount of negative feedback. It is simply much easier to tweak the two halves of the circuit into identical symmetry than to eliminate all the distortion in each half of the circuit.

The result has been a successful series of high power amplifiers offering low distortion, and stunning dynamic range and control, with only two gain stages and very minimal feedback.

Supersymmetry™ is ideally used to obtain high quality performance from very simple gain circuits, and particularly favors single-ended Class A topologies due to their smooth second harmonic characteristic, which cancels easily.

Single-ended Class A has long been known as the “King of the Class A’s”, the simplest, most pure and least efficient form of audio amplifi- cation. Before the Aleph™ amplifiers, it was reserved for preamplifier circuits, high quality amplifier front-ends, and other very low power output stages.

US Patent # 5,710,522 describes the single-ended Class A power ampli- fier biased by a constant DC current source which negatively “ghosts” the speaker load with simple but effective current modulation. If you have followed developments in audio for the last 10 years, you know this design as the Pass Laboratories Aleph™. The Aleph™ is an incredibly successful ground breaking amplifier design, hailed in Stereophile maga- zine as “The Amplifier of the Decade” and winner of virtually every international design award for audio that we know of.

The key virtue of the Aleph™ design lies in its simplicity and effective- ness. With only two stages and no adjustments it delivers measured performance rivaling the most complex designs, but retains the sonic elegance and nuance of a truly minimalist gain path – only two gain devices in series from input to output.

The two design concepts are not mutually exclusive, and we approached the development of the XA series with an eye to creating a warm/sweet X amplifier, or conversely, a powerfully dynamic Aleph™. The success- ful result is a circuit which is described as balanced single-ended Class A, consisting of two balanced Aleph™ amplifiers sharing a single dif- ferential input pair of transistors.

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Pass Labs XA200 owner manual Aleph Single-Ended Class a
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XA200 specifications

The Pass Labs XA200 is a distinguished power amplifier that is acclaimed for its exceptional performance and remarkable build quality. Designed for audiophiles who demand the highest fidelity in their audio systems, the XA200 offers a unique blend of power, clarity, and musicality that sets it apart from the competition.

At the heart of the XA200 is a Class A topology, renowned for its ability to deliver pure and uncolored sound. This design ensures that the amplifier operates in its most linear region, providing a smooth and accurate response across the frequency spectrum. With an impressive output of 200 watts per channel into 8 ohms, and effectively doubling that power into 4 ohms, the XA200 is capable of driving even the most demanding loudspeakers with ease.

One of the standout features of the XA200 is its innovative use of the Pass Labs’ patented Feedforward error correction technology. This groundbreaking approach reduces distortion to extremely low levels, enabling the XA200 to produce a highly detailed and transparent soundstage. Additionally, the amplifier employs a combination of high-quality components, including custom-designed power supply transformers and large reservoir capacitors, to ensure stable operation under various load conditions.

The build quality of the XA200 is also noteworthy. Encased in a robust chassis with a striking aesthetic, this amplifier not only looks elegant but is designed to minimize vibration and resonance. The dual mono configuration of the XA200 ensures that each channel operates independently, further enhancing the overall sound quality and separation of instruments.

In terms of connectivity, the XA200 is equipped with balanced XLR inputs and single-ended RCA inputs, allowing for versatile integration into different audio setups. It also features a switching power supply that enhances its efficiency, ensuring that the amplifier remains cool even during extended listening sessions.

Overall, the Pass Labs XA200 is a testament to the brand’s commitment to excellence in high-end audio. Its combination of power, advanced technologies, and impeccable build quality makes it an ideal choice for audiophiles seeking a rich and immersive listening experience. Whether used in a dedicated home theater or a refined stereo system, the XA200 stands ready to reveal the true potential of any musical recording.
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