The Conrad-Johnson ART 150 Power Amplifier Forging a Work of Art!

By Rob Johnson

Celebrating 40 years in business, Conrad-Johnson released their special edition flagship amplifiers, the ART150, which is a single chassis stereo version and the monoblock ART300s. According to C-J, the amp represents the culmination of all their design expertise to date, and they will produce only 250 of them. For those needing more power, C-J also offers the new ART300 monoblocks. Like their smaller stereo sibling, production is limited 250 pairs.

C-J’s entry-level tube amplifier, the Classic Sixty-Two SE (reviewed here in issue 84) offers marvelous sound and represents an amplifier I could live with happily. That said, the ART150 defies expectations, delivering an extraordinary musical experience that few components in my personal experience have.

Creating a classic

Like all recent C-J gear, the new ARTs are available in gold anodized finish only. All the components reside within a 16.3”D x 19”W x 8.75”H metal chassis, resulting in an overall weight of  80 lbs. The ART’s aesthetics adhere to the style brief set by current Conrad-Johnson designs. As with all C-J products, the ART is a collaborative effort of Lew Johnson, Bill Conrad the rest of the C-J team.

The hefty base serves as the amplifier’s foundation, with custom power and output transformers shielded in a black metal enclosure jetting upward from the rear. A rounded Lucite frame with tube-sized holes in it protects the semicircle of three 6922 tubes up at the front face. Between these two functional structures rests a protective metal cage, with a front panel also made from clear Lucite. The resulting “window” makes it easy to admire the row of four KT150 driver tubes from a distance. The most recent offering from Tung-Sol, the elongated egg shape of the KT150 gives the ART amplifier more of a space age flair.

The front of the ART is a model of simplicity. A single, quarter-sized power button resides toward the right side, illuminated by a subtle amber LED when activated. When depressed the amp warms the tubes slowly, helping extend tube life. You might hear a few pings and pops through the speakers while the tubes warm up, but once the ART achieves optimal voltage and temperature one’s ear must be very close to the woofer or tweeter to detect audible hiss.

Mining for the best parts

As old wisdom suggests, “It is what’s inside that counts.” In the case of the ART150, careful component choices result in staggering performance. C-J sought the best possible parts for the new ART, right down to the type of internal wiring, with the wide-bandwidth output transformers and Teflon capacitors being custom-made solutions. Also under the hood are laser-trimmed metal foil resistors chosen for their high levels of performance in the sensitive signal path. As a single ended design, the ART accepts only RCA interconnects from a preamplifier. The high quality gold-plated input terminals offer both excellent electrical transmission and a secure grip on cables.

A set of metal five-way binding posts on the back of the unit facilitate connection of spade, banana, or bare-wire cable terminations with ease. Spades used in my case secure quickly and very firmly under the posts. For those without muscular fingers, a 7/16-inch plastic binding post wrench fits over the nut correctly, allowing extra leverage. If you elect this route, consider an approach of gentle assertiveness, remembering you are not bolting together a skyscraper’s support beams.

The Conrad Johnson design philosophy has always centered around meticulously executing simple circuit designs – a big part of why they don’t produce balanced circuit designs. Taking the simplification mantra further in this amplifiers, a single pair of KT150 output tubes per channel replaces four KT120 tubes per channel in the original ART amplifier, with the new design producing 150 watts per channel, up from the 140 per channel available in the original.

Swift set up

The tubes are carefully packed inside the tube cage, so this will need to be removed to fit power and driver tubes. Each tube box is wrapped in black tissue paper giving the unpacking process an extra touch of class.

Like every other C-J power amplifier, the user must manually bias the power tubes after installing them. The process is surprisingly easy, using a simple plastic screwdriver included in the ART150 package. After a new set of tubes are socketed, twist the biasing screw just enough to extinguish the small yellow LED next to each tube. C-J suggests doing this again after an hour or so of use, and again every six months to extend the life of the tube set. When re-tubed, the biasing process should be repeated.

The ART requires significant break in due to the custom Teflon capacitors and other electronics within. C-J completes a 5-day burn-in before ART amplifiers leave the factory. During that time, the C-J team can ensure no component inside the amp fails before shipping, and do a listening test. I gave the ART150 another 200 hours of play time to ensure it reached its full sonic potential, and the sound did gain improvement during that period.

It is best to shut down the amp when not using it. Doing so will help maximize valuable tube life. ART warm-up time from a cold start is a scant 15 minutes, so the wait for optimal sound is never a long one. Absence makes the heart grow fonder, right?

Jewelry for the eardrums

C-J’s tagline “It Just Sounds Right” is not just marketing hype. In this case, those four words may comprise the shortest product review ever written. However, quantifying “Right” requires quite a few more words because a lot is right with this amp.

With the ART150, C-J did not just jump over the high bar set by the Classic 62. Instead, it seems they used a ten-foot pole to vault over it. The Classic 62 is a fantastic amp by any measure. However, the ART exceeds the Classic 62’s capability in every way.

With the ART150, my entire listening room becomes part of its huge projected soundstage. Music extends well beyond the left and right speaker boundaries, wrapping around the edges of the space. When music dictates it, spatial cues place instruments and vocals above, below, behind, or well out in front of the speakers. Imaging presented by the ART remains not only precise and defined, but almost tangible. Instruments and vocals layered over one another retain independent space rather than collapsing into one another. The three-dimensional nature of the music experience proves immersive, and time evaporates while listening to song after song. Even with familiar tracks, subtle sound effects are much easier to discern, offering details few components retrieve so exceptionally. Occasionally, music freed by the ART will surprise me, as if sneaking up next to my listening seat before revealing itself. Even older recordings reveal a few surprises. For example, engineered vocal effects in “By My Side” by INXS extend the background voices, well… right by my side. Alternately, the bar chime sounds in Depeche Mode’s “Everything Counts” seem to leap forward to a point a few inches from my ears. To have an audio component capable of detailed projection that catches me off guard like this is equally rare, eerie, and thrilling.

The ART will reveal every nuance of a song for better or worse. Great recordings sound quite realistic. However, on less-than-stellar tracks, the ART exposes any shortcoming too. For instance, listening to Santana’s Supernatural, the level of compression is evident. Cymbals lack both the splash of impact and a lingering decay. In contrast, extremely well-recorded albums like Johnny Cash’s American IV: The Man Comes Around provide the honest illusion of Cash sitting in the room. Few amplifiers I have experienced offer this degree of revelation. The ART represents quite an achievement indeed.

Despite the level of detail, this C-J’s purposeful voicing choices offer organic, natural, and forgiving sound. Even with some strident or sibilant recordings, ear-twitching spikes lose their sting and seem much more refined through the ART. C-J manages to capture every detail within a song but accomplishes the trick of making edgy sonics more enjoyable.

Forget any pre-conceived notion that this tube amplifier might generate watered-down or mushy bass. The ART150 rides the perfect balance between bass depth, punch, and naturalness. Similarly, high notes offer a welcome sparkle. Both male and female vocals glide through this amp’s circuitry, providing the listener a lush and luxurious musical experience as they emerge. Regardless of music genre, the ART never failed to deliver fantastic music, exceeding my expectations for an audio component.

Go for the gold!

Reaching audio heaven comes with a cost. Retailing at $19,500 for the limited edition ART150 and double that for the ART300 monos, either choice represents a significant investment. However, considering the extensive research and design process, no-compromise electronics, and the stellar sound this amplifier produces, one should expect a component of this magnitude to have a price commensurate with its performance level.

Those familiar with any piece of tube gear know they need replacement over time, so unlike solid-state amps, an ART owner should budget for planned maintenance. C-J suggests the ART’s tubes have a longevity of two or three years depending on usage. KT150s cost around $90 each and prices for 6922s can range widely depending if they are modern production or new old stock. Budget at least $500 every few years for a complete re-tube. The ART300 monos, each of which is essentially an ART150 optimized for a single channel, would double that tube cost.

Yes, I am utterly stunned by the ART150’s sonic prowess. Among amplifiers I have had the pleasure of evaluating at home for an extended period, the ART deserves a place on a tiny list of amps I would enjoy for the long haul. We will have to wait and see what C-J creates for their appropriately-golden, 50th anniversary! For now, the ART earns a place among those scarce components that offer such an outstanding level of performance it could halt one’s long journey in pursuit of better gear. Kick off those worn-down trekking shoes, relax, and just enjoy the music.

I am giving the ART150 amplifier my highest praise: I purchased the demo unit as a reference component. If you are seeking a flagship amplifier to enjoy for many years to come, do yourself a big favor and head to your local Conrad-Johnson dealer for a demo. Like me, you may find you cannot walk away from the ART150. Grab one before these limited-edition units are gone!

Further Listening: Jeff Dorgay

Even though Conrad-Johnson has been refining their designs for decades now, they’ve made some pretty incredible tube amplifiers over the years. Audiophiles the world over still discuss many of their Premier designs in hushed conversations, with reverence.

Not only is the ART 150 one of the most musical revealing amplifiers I’ve heard, the combination with C-Js flagship GAT 2 Preamplifier has me squeezing my adjective gland for some new superlatives. I can not find them. If you already have one of CJ’s top preamps, the ART 150 will take you somewhere rare and special. If you don’t, you’ll be shopping. I won’t taunt Rob with the GAT until he recovers from the ART 150 purchase.

Everything Rob points out about the ART 150, is heightened even further when paired with the GAT 2. It’s worth mentioning that the ART 150 is no slouch with an ACT 2 either, so even if you have one of these on your equipment rack, it is a worthy partner for an ART 150.

As a friend pointed out recently, we are really living in an exceptional period for audio, no matter what your budget might be. With so many of the industry’s top designers benefitting from decades of experience, creating their best work. It’s often said that it takes 10,000 hours to master something. 40 years of refining greatness results in the ART 150 power amplifier. More often than not, tube power amplifiers give you musicality/tonality, inner detail, or massive imaging prowess, but rarely all three. The ART 150 does that and more – adding major dynamic swing and bass control. This level of resolution, delicacy and freedom from fatigue is what makes the ART 150 so special. That is why it is our Amplifier of the Year for 2017.

The Conrad-Johnson ART 150 Stereo Power Amplifier

MSRP:  $19,500


Analog Source: SME Model 10 with SME V and Model 10 tonearms. Dynavector 17D3 and Denon DL-103R cartridges

Digital Sources: Mac Mini, Roon Music Service, Simaudio MOON 780D DAC, Oppo BDP-103

Amplification: Conrad-Johnson Classic 62, Burmester 911 Mk3

Preamplification: Coffman Labs G1-B

Speakers: GamuT RS3i, JL Audio Dominion Subwoofers

Cables: Jena Labs

Power: Torus AVR 15 Plus, RSA Mongoose power cords

Accessories: ASC tube traps, Mapleshade Samson audio racks, Coffman Labs Equipment Footers, AudioQuest Jitterbug, Atomic Audio Labs Mac Mini stand