First Watt J2 Stereo Amplifier
- Created on Thursday, 15 November 2012 00:00
- Written by Vade Forrester
Pass Labs amplifiers have inspired more than a few moments of lust in the hearts of veteran audiophiles. Big, beautiful, powerful, and expensive, their sound, according to some, has advanced the state of the art. But audiophiles may not know about designer Nelson Pass’s second company, First Watt, which produces a line of electronics smaller, cheaper, but possibly even more innovative than the mighty Pass Labs models. The First Watt amps give Nelson Pass an opportunity to try new circuit-design technology on a limited scale. The first FW products were unusual amplifiers designed to work well with single-cone drivers such as the legendary Lowthers, but over the years the line has been expanded to include preamps and crossovers.
Where did Pass come up with the name “First Watt”? Some years ago, reviewer Dick Olsher astutely commented that, “If the first watt of an amplifier doesn’t sound good, why would you want 199 more of them?” (cited in Robert Harley’s The Complete Guide to High-End Audio, Fourth Edition, p. 96). Even with inefficient speakers, it’s surprising how much volume can be produced by a single watt of power. With that idea in mind, Pass set about designing a series of amplifiers that would complement high-efficiency, single-driver speakers. Although he’d designed several circuits for do-it-yourself (DIY) hobbyists, Pass realized that many klutzes, like me, lack the skill and/or will to complete a DIY project, and so formed First Watt, to build a limited run of each design. To keep costs down, all First Watt amps have the same simple chassis and faceplate. They look sleek and professional, but eschew some of the audio jewelry that make Pass Labs amps so mouthwatering. But what’s inside is quite unusual.
The J2 amplifier ($4000 USD) reviewed here is one of the more “normal” First Watt amps, but that’s not to say it’s a conventional design. All the J2’s transistors, even the output transistors, are JFETs. Why JFETS? Because they sound superb. JFETs aren’t new; they’re widely used in low-level circuitry. But although Sony and Yamaha produced amplifiers with JFET output devices a number of years ago, until recently, no one was making JFETs capable of functioning as amplifier output devices. Now they are. Only two JFETs per channel are used, making the amplifier a single-ended transistor design. If the term SET weren’t already being used to denote single-ended-triode tubed circuits, it could be applied to the J2. Like most class-A amps, the J2 runs hot. It doesn’t glow in the dark or require oven mitts to handle, like some amps I’ve experienced, but it was definitely uncomfortable to keep my finger on it for long.
The J2 measures 17”W x by 5.25”H x 14.5”D (43.18 by 13.34 by 36.83cm) and seems fairly light, which my recently repaired hernia appreciated. The J2’s case is black, with horizontal heatsinks along each side. Those fins get pretty hot, but shouldn’t be too hot to touch for as long as five seconds -- Pass’s test for whether an amp is adequately ventilated. Only silver faceplates are available. Although the same enclosure is used by other First Watt models, it doesn’t look like a cheap DIY item; the faceplate is impressively thick, and the metalwork is all first-rate.
Claimed to deliver 25Wpc into 8 ohms (or 13Wpc into 4 ohms), the J2 has a damping factor of 20 at 8 ohms. Although it has both balanced (XLR) and unbalanced (RCA) inputs, its input circuit is balanced; it comes with a jumper across two pins of the XLR input connector, to strap it for unbalanced inputs. If you want to use balanced inputs (which I did), you must remove the jumper. The input impedance is 100k ohms, with a 1.4V input needed for rated power output. The claimed distortion at 1kHz is 0.025%, the gain 20dB, and the noise 100µV, 20Hz-20kHz, unweighted -- the J2 was dead silent.
Setup and use
I usually place small amplifiers on the bottom shelf of my equipment rack, where they get the most ventilation, and that’s where the First Watt J2 went. Clarity Cables Organic balanced interconnects connected the J2 to my Audio Research LS27 line stage. The J2’s stock power cord appeared heavy and serious enough, not a throwaway, so I used it. Speaker cables were the very open-sounding Clarity Organics.
At the factory, Nelson Pass burns in each J2 in for 96 hours to eliminate JFET failure, but he doesn’t believe in longer burn-in. Just in case it might make a difference, I played the J2 for about 200 hours before doing any critical listening. The results vindicated Pass: I heard little if any change between the J2’s sound at delivery and 200 hours of play later.
One thing I really liked about the J2 was that it emitted no turn-on/off thumps. The one thing I found annoying was more of a personal preference: Its on/off switch is low and almost centered on the rear panel. With the J2 sitting on the bottom shelf of my rack, it was hard to reach around to turn it on or off.
The J2’s chattily informative manual tells the reader a lot about its design, and offers basic setup instructions. I appreciated that the manual didn’t begin with numerous lawyer-written pages telling you not to use the amplifier underwater and other such safety trivia, which usually makes me want to toss the manual in the fireplace.
The J2 didn’t sound like most solid-state amplifiers I’ve heard. I’m tempted to describe its sound as a bit like that of a traditional SET amp -- a very clean, detailed, low-distortion SET. Also like a SET, the J2’s sound was tonally rich and full. And like a tube amp with a decent power supply, the J2 had a lively sound that bespoke excellent dynamic performance. It didn’t just play loud; it clearly distinguished between the minute changes in loudness that we call microdynamics.
As it often is, one of the first selections on my playlist was Folia Rodrigo Martinez, ripped to a WAV file from Jordi Savall’s La Folia 1490-1701 (16/44.1 WAV, Alia Vox). I’ve listened to this piece so often it’s burned into my eardrums, but I always look forward to hearing it one more time. Not only did the continuously varying loudness level show how effortlessly the J2 could track dynamic changes, it revealed prodigious bass. I thought at first I’d forgotten to turn off my subwoofers, so low did the bass go -- substantially deeper than any other amp has driven my Affirm Audio Lumination speakers. And that bass wasn’t merely deep; it had great weight and impact. I don’t think I’ve heard another amplifier that did bass as well through these speakers as did the J2.
The First Watt also revealed a ton of detail. Folia Rodrigo Martinez has an assortment of percussion instruments, including castanets, that mostly remain submerged in the musical background -- but about two-thirds of the way through, the castanets explode in a cacophony of clatter. Since this passage is still not very loud, many amps keep it submerged in the background of percussion. Not the J2 -- it didn’t spotlight the castanets, but it clearly portrayed them.
I recently ran across Praetorius: Dances from Terpsichore and More, performed by the Praetorius Consort led by Christopher Ball (CD, Alto ALC 1076). One of the “and More” selections is a three-movement dance suite by Thoinot Arbeau, a 16th-century French composer of whom I’d never heard. (The CD seems to attribute the suite to Gregorio Lambranzi, an 18th-century Venetian dancing master.) The perky music is irresistibly full of life, and the musicians clearly have a thumping good time with it. The instruments include several very high-pitched chimes, and the J2 easily distinguished their pitches, as well as the complete envelope of each note (initial transient as the chime is struck; sustain, where the chime develops its complete harmonic structure; and decay, as the chime’s audibility dwindles to silence). The J2 reproduced the chimes as well as any amplifier I’ve heard, but never sounded at all peaky or etched. In summary: great high-frequency performance.
To evaluate the J2’s soundstaging abilities, I turned to an old standby, the Tallis Scholars’ recording of Allegri’s Miserere and other works (24/96 FLAC, Gimell/Gimell). In the Miserere, a small group of soloists is set back a fair distance from a larger choral group that stands toward the front of the recording space. Voices in the front group seemed unusually detailed, more textured, and I could make out the words better than usual. If I spoke Latin, I could have understood what they were singing. The soloists in the rear were clearly separated by some distance from the main choir, but the reverberations seemed more organized than I’d previously heard -- the recording venue, a room in a church, seemed more like a continuous room, not just groups of singers front and rear separated by a reverberant smear. That was a first.
Reviewers have an unwritten rule: Every audio review must include at least one Girl With Guitar recording -- not an unpleasant task. I turned to my absolute favorite GWG album, Eva Cassidy’s Simply Eva (16/44.1, Blix Street/HDtracks). After listening to “Over the Rainbow,” I checked a personal fave, “Time After Time,” a cover of the Cyndi Lauper hit. Here, slightly emphasized mid-highs highlighted the higher registers of Cassidy’s guitar. A quick check of Ottmar Liebert’s extremely well-recorded One Guitar (24/96 FLAC, Spiral Subwave/HDtracks) showed that, on most guitar recordings, there’s no emphasis of mid-high frequencies. So the J2 showed me something new about this recording.
My Atma-Sphere S-30 Mk.III power amplifier is rated at 30Wpc into 8 ohms, which is comparable to the First Watt J2’s 25Wpc. (The S-30 Mk.III sold for $3300; the current version, the S-30 Mk.III.1, sells for $3990.) Unlike many tube amps, the S-30 doesn’t use output transformers, which, despite the best design efforts, smear the output. The Atma-Sphere also runs in class-A, but uses triode tubes -- lots of them -- as output devices. Input is via another type of triode, the popular 6SN7 tube. The Atma-Sphere is a push-pull design, with the low distortion expected from such a circuit. With a total of 16 tubes, including ten output tubes, it runs extremely hot. With both amps sitting on my rack’s bottom shelf, the J2 heats up the shelf above it. The Atma-Sphere heats up the shelf above it, the preamp sitting on that shelf, and the shelf above the preamp. That’s hot.
The Atma-Sphere’s power increases into my Affirm Luminations’ 16-ohm impedance; the J2’s power drops into a 16-ohm load. So in this comparison, we’re comparing a 45Wpc amp to a 12.5Wpc amp. Neither amplifier seemed to run into any dynamic compression limiting, though. Sometimes, it’s nice to have speakers with 103dB sensitivity.
The Atma-Sphere is fairly quiet, though not as quiet as the J2. With Folia Rodrigo Martinez, the bass was quite powerful -- amazingly so for a tube amp. But the J2’s bass seemed to go very slightly deeper, and with better detail. At the other end of the audioband, the high chimes in the Arbeau dance suite were plainly audible, but the J2’s highs were slightly more extended, and seemed a smidgen purer. Both amps were very dynamic, but the Atma-Sphere seemed to have a hint more oomph. But remember -- into my speakers, the Atma-Sphere produces 45Wpc, the J2 12.5Wpc.
The Atma-Sphere S-30 Mk.III has always sounded very spacious to me, and with Allegri’s Miserere it seemed just as spacious as the J2, with perhaps just a tiny bit better portrayal of soundstage depth. But both amps were outstanding in this area. Triodes plus voices equal audio bliss, as illustrated by the Eva Cassidy album -- except that the J2 sounded just as luscious, and perhaps even cleaner. A hard choice.
This was a close match. The Atma-Sphere has been my go-to amp with the Affirm Luminations, and despite a lower input sensitivity (3V), it never seems to lack power or run out of dynamic headroom. But again, it’s producing nearly three times the J2’s power, so it’s not surprising the Atma-Sphere seemed to have a tad more headroom.
The J2 was quieter than the Atma-Sphere, and ran a lot cooler. But its main advantage is obvious: Tubes inevitably fail, and the Atma-Sphere has 16 of them. It’s a pain even to discover which tube is defective -- unless it arcs internally, which the 6AS7G triode tends to do, accompanied by a horrific noise. And although the 6AS7G is self-biasing, having to replace any tube is a pain in the posterior. I don’t mean to suggest that the Atma-Sphere has reliability problems; it’s actually been one of the more reliable tube amps in my collection. But eventually, every tube fails.
I expected Nelson Pass’s First Watt J2 power amplifier to be almost as good as a good tube amplifier, but it wasn’t -- it was better than most tube amps I’ve tried. It’s possible to find better-sounding tube amps, but you’d better be prepared to part with a lot more cash. With extended and well-controlled bass, a detailed and tonally rich midrange, and extended but not edgy highs, the J2 had many of the features of the tube amps I prize. But with the J2, you’ll never have to replace a tube.
Some First Watt amplifiers are rather specialized, limiting what preamps and speakers they will work with, but the J2 is relatively conventional in its interface requirements. Obviously, its 25Wpc output won’t drive low-efficiency speakers to deafening levels in large rooms. That’s where Pass Labs amplifiers shine.
The J2 is one of the best amplifiers I’ve heard, regardless of the type of circuit used, and it provides an opportunity to own a product from audio master Nelson Pass at a moderate cost. I thought I was a hopeless tubeaholic, but I think I’ve just been cured.
. . . Vade Forrester
- Speakers -- Affirm Audio Lumination
- Amplifier -- Atma-Sphere S-30 Mk.III
- Preamplifiers -- Audio Research PH5 phono preamp, Audio Research LS27 line stage
- Source -- Audio Research DAC8 DAC, Aurender S10 music server
- Interconnects -- Audience Au24 e balanced, Clarity Cables Organic
- Speaker cables -- Clarity Cables Organic
- Power cords -- Audience powerChord e, Clarity Cables Vortex
- Digital -- Gold Starlight 6 S/PDIF cable
First Watt J2 Stereo Amplifier
Price: $4000 USD.
Warranty: Three years parts and labor.
General Amplifier, Inc.
P.O. Box 7607
Reno, NV 89510-7607