X0.2 Owner’s Manual

With balanced operation, the common mode rejection of the preamp reflects the intrinsic common mode rejection of the topology, the matching of the gain devices, and the matching of the attenuator channels. In this case we have been able to keep the total mismatch to about .1%, for a common mode rejection of greater than -60 dB.

The input system of the pre-amplifier will exhibit full common mode noise rejection with passive balanced sources, where the negative input is connected to ground at the source through the appropriate source impedance. This allows adaptation of unbalanced sources to balanced operation with passive cable connections in a manner that achieves the noise rejection of active balanced sources.

The use of a micro-controller allows all of the pre-amplifier functions to be repeatable and accurately controlled. The micro-processor only controls the operational functions of the pre-amplifier. At no time do any of the input or output signals come into contact with the digital control signals. The digital circuits are powered by a power supply that is completely separate and isolated from the analog supply. Should it ever be necessary to update the software that controls the functioning of the preamp, only the socketed micro-processor need be changed.

The analog power supply for the X0.2 consists of a toroidal power transformer delivering an unregulated +/- 45 volts which is then actively regulated before feeding passive filtering and powering the constant current sources which bias the gain stages. Each channel has

its own regulation. The power supply noise reaching the circuit is on the order of one microvolt, and the little of that which gets through the circuit is differentially rejected at the output in a balanced system.

The relays and control systems are regulated independently. All digital circuits receive their power from a separate toroid, which, like its analog counterpart, is also double regulated, and carefully filtered.

Muting relays, which delay connection during turn-on, additionally shut off the output when insufficient power supply is available to maintain regulation, thus guarding the output of the pre-amplifier. The pre-amplifier is designed to run constantly, and will exhibit optimum measured performance within about 10 hours of turn-on. For this reason a power switch is intentionally omitted.

The X0.2 consists of three machined aluminum chassis. Likewise, the remote control device is ensconsed in its own palm sized aluminum chassis. All four chassis components are machined from solid aluminum material on computer controlled vertical milling machines. There are no sheet metal components is this product. All engraving is done by laser to make it easy to read and provide a durable and attractive finish.

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Pass Labs pre-amplifier owner manual
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pre-amplifier specifications

Pass Labs, an esteemed name in the realm of high-fidelity audio equipment, has garnered a reputation for producing premium amplifiers and pre-amplifiers designed for audiophiles who crave exceptional sound quality. Among its acclaimed offerings is the Pass Labs pre-amplifier, a device that captures the essence of music reproduction with unparalleled precision and clarity.

One of the defining features of Pass Labs pre-amplifiers is their use of a fully balanced differential circuit topology. This design significantly reduces common-mode noise, preserving the integrity of the audio signal and ensuring that the listener experiences sound as it was intended to be heard. This topology is especially effective in eliminating distortion and improving dynamic range, hallmarks of a quality audio experience that Pass Labs strives to deliver.

The pre-amplifier is equipped with premium-grade components, including high-quality capacitors and resistors, which are crucial for maintaining signal purity. These components contribute to the overall fidelity of the sound, allowing for rich, detailed reproduction across a wide frequency range. Additionally, the circuit design is optimized for low noise and low distortion, ensuring that even the most subtle nuances of music are faithfully rendered.

Another standout characteristic of the Pass Labs pre-amplifier is its seamless integration with various audio sources. With multiple input options, including XLR and RCA connectors, the pre-amplifier accommodates a variety of devices, from turntables to digital players. This versatility makes it an ideal choice for audiophiles with diverse audio setups, ensuring compatibility regardless of the source.

To enhance user experience, Pass Labs incorporates intuitive controls and a user-friendly interface, allowing for easy adjustments and monitoring of audio settings. Features such as a built-in volume control and selectable input sources provide convenient options for users, ensuring a streamlined listening experience.

Moreover, the robust build quality of Pass Labs pre-amplifiers exudes a sense of durability and sophistication. The solid chassis and meticulous attention to detail not only serve to protect the internal components but also reduce external vibrations that could interfere with sound performance.

In conclusion, the Pass Labs pre-amplifier stands as a prime example of engineering excellence in high-fidelity audio. With its balanced differential circuit topology, premium components, and user-friendly features, it is designed to meet the discerning demands of audiophiles. Whether in a home listening environment or a professional setting, the Pass Labs pre-amplifier promises to deliver an extraordinary audio experience that brings music to life.
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