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Pass Labs and First Watt were founded by hi-fi legend Nelson Pass. After co-founding and later selling Threshold Audio, Pass began working out of his Auburn, California, home in the early 1990s to develop prototypes of single-ended Class A amplifier designs under the name Pass Labs. Pass Labs quickly became known for its commercially produced Aleph, X, and XA Series amps, and preamps. Pass later started First Watt as a passion project focusing on low-power amps for a niche audiophile audience. Today, Pass splits his time between the two companies, with production happening in Pass Labs' facility in Foresthill, California.
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.
Pass Labs helped popularize solid-state, Class A power amplifiers. Pass Labs' first product, the Aleph 0 amplifier, operated as 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 cascoded differential pair of transistors and a large bank of complementary output followers. This groundbreaking design informed all subsequent Pass Labs amplifiers.
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.
By the late 1990s, Pass was nurturing a creative side project out of his home. First Watt can be classified as a "mad scientist" offshoot of Pass Labs that allowed Pass to explore low power, single-ended Class A amps with an emphasis on sound quality. Pass started First Watt as a "kitchen table" venture that would allow him to hand build niche amplifiers in low numbers without drawing on the resources of Pass Labs. In other words, First Watt was a way for Pass to explore designs outside of the mainstream of commercial audio without the constraints of economic viability. It was an opportunity to experiment in the marketplace with products that may or may not ever be popular. Nelson wanted to explore a variety of amplifier designs in what he thought of as neglected areas -- amplifiers that might not fit into the mainstream and were probably not appropriate to the more commercial Pass Labs.
The name First Watt is a nod to The Absolute Sound's Dick Olsher, who is known for saying that “the first watt is the most important watt.” This idea has also been expressed by others as: “Who cares what an amplifier sounds like at 500 watts if it sounds like crap at one watt?” The products that First Watt makes are below 25 watts, designed for the consumer who doesn't listen at high volumes. As Pass has said, anything First Watt does can be done with one watt; it's loud enough, and there are people who feel the same.
First Watt is known for high-quality, modest power, limited-production amps. There will be 100 or so of a given model before it is discontinued. At a given time, only a handful of models will be in production before they are discontinued. Nelson Pass is quick to acknowledge that First Watt amplifiers will not appeal to everyone; he targets a subset of audiophiles who disregard the usual performance specs. With quirky characteristics and output power ratings of 25 watts or less, these amps are out of the mainstream, reflecting quality in simplicity and intrinsic linearity. In fact, Pass says that in his experience, simple linear circuits tend to sound better. He thinks they are more interesting and subtle than complicated circuits, and he finds that measurements and subjective sound quality correlate better with simple gain paths. Exploring their potential for high performance is what he likes to do. But for people with efficient loudspeakers who listen at reasonable levels and who are obsessed about subjective performance, First Watt may be just the answer.
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.
According to the website PassDIY.com, Nelson Pass is a valuable contributor to the audio DIY scene, where he is affectionately known as "Papa." He's also an active contributor at www.diyaudio.com. Followers say he has a knack for explaining engineering concepts in terms that are accessible to audio newbies and those without a scientific background. What's more, he enjoys doing it, viewing it as a two-way street. People who want to build their own amplifiers get advice from Nelson Pass himself, and Pass gets to voice some cool concepts and ideas that might otherwise never see the light of day.
