INT-25 Amplifier

What is the power output of the Pass Labs INT-25 Integrated Amplifier?

The Pass Labs INT-25 Integrated Amplifier delivers 25 Watts per channel into 8 ohms. Despite its moderate power output, the INT-25 is designed to excel in driving high-quality speakers with precision and clarity. Its Class A operation ensures a clean and detailed sound signature, making it an excellent choice for discerning audiophiles who prioritize sonic purity.

What are the key features of the Pass Labs INT-25 Integrated Amplifier?

The Pass Labs INT-25 is packed with features that appeal to audio enthusiasts. It includes a fully balanced input stage and a discrete, direct-coupled FET output stage for exceptional signal integrity and low distortion. The INT-25 also features a high-quality volume control system, remote control operation, and a home theater bypass mode for easy integration into a multi-channel setup. Its compact size and elegant design make it versatile and suitable for a variety of audio systems.

Can the Pass Labs INT-25 drive difficult or inefficient speakers?

Yes, despite its modest power rating, the Pass Labs INT-25 is capable of driving a wide range of speakers effectively. Its Class A operation and high-current capability allow it to handle challenging speaker loads with ease. The INT-25 pairs particularly well with high-efficiency speakers that benefit from its clean and detailed amplification. Users can expect a dynamic and engaging listening experience, even with speakers that may be considered demanding.

Does the Pass Labs INT-25 require any special considerations for setup or maintenance?

The Pass Labs INT-25 Integrated Amplifier is designed to be user-friendly and relatively straightforward to set up. It does not require bias adjustments, as it is a self-biasing Class A design. However, users should ensure proper ventilation for optimal performance, as Class A amplifiers can generate heat. Adequate ventilation will help maintain the amplifier's performance and longevity. Additionally, it is recommended to provide sufficient space around the amplifier for airflow and to follow Pass Labs' guidelines for safe and optimal operation.

Who is Nelson Pass?

Nelson Pass, the man behind Pass Labs and First Watt, has been designing and building amplifiers for decades. His early passion, however, was speakers; at age 14, he started assembling loudspeakers. As a college student studying physics at the University of California-Davis, he co-founded a speaker company called PMA. He also worked for ESS, where he designed crossovers and enclosures. After college, with his interest having shifted toward amplifiers, Pass co-founded Threshold Electronics (now Threshold Audio). His achievements during the Threshold years include developing the first dynamically biased Class A amplifier circuit; developing a fully cascode audio power amplifier; and developing the STASIS stereo preamplifier and power amplifier. During the 1980s, Pass designed the Adcom GFA-555 amplifier. Later, after selling Threshold, he started Pass Labs in 1991 and First Watt in 1997. Pass holds several patents related to audio circuits.

How did Pass Labs make its name?

Pass Labs helped popularize solid-state, Class A power amplifiers. Pass Labs' first product, the Aleph 0 amplifier, operated as a single-ended Class A up to its 70-watt rating and in push-pull Class A at higher wattage. The Aleph series of amplifiers, some of the first solid-state amps that were said to be "tube-like" in sound, operated pure class A and contained internal circuitry using MOSFETs. The Aleph amplifiers had a unique appearance, a cube with heat sinks on all four sides, a solution to the heat generated by the class-A design. This can be attributed primarily to the specific MOSFETs used and the minimum number of gain stages that were implemented in the design. Pass Labs also developed the Super-Symmetry™ ("Su-Sy") circuit, which achieves exceptionally low distortion and noise levels. In 1998, Pass Labs released the X1000, the first amplifier using the patented SuperSymmetric™ topology. The X1000 achieved 1000 watts with high performance, local feedback, and only two gain stages: a cascaded differential pair of transistors and a large bank of complementary output followers. This groundbreaking design informed all subsequent Pass Labs amplifiers.

What else does Pass Labs make?

In 2002, Pass Labs unveiled the first XA amplifiers, combining the X and Aleph topologies into balanced single-ended Class A amplifiers with many of the characteristics of both the X and Aleph series. The current Pass Labs lineup includes Class A amps (XA and Xs Series), Class AB amps (.8 Series), line preamps (Xs and XP Series), phono preamps (Xs and XP Series), integrated amps (INT Series), and one headphone amp.

What is the relationship between Pass Labs and First Watt?

When he started Pass Labs, Pass did everything out of his home. In 1997, having outgrown the space, Pass Labs moved into commercial space in Foresthill, California. When Pass started First Watt, it was a "kitchen table" venture, with work once again happening in his home. In 2016, with production demands not leaving him enough time to pursue the vast array of yet-to-be-designed amps, Nelson handed the business end of First Watt over to Pass Labs. Pass Labs took over the building of First Watt amplifiers as well as marketing and distribution. There's a synergy between the two operations, in that Pass Labs gets to gather up some of the more interesting First Watt finds and repurpose them as more commercially viable designs. Today, Pass splits his time between First Watt and Pass Laboratories.