Art Audio's new Carissa is a 16wpc, 845-based, no negative feedback, single-ended triode amplifier that operates in pure Class A. Retailing at $3,995 with black chassis and chrome accents -- or $4,495 with hand-polished stainless steel case -- it is neither cheap nor bank-breaking. Further specs include input sensitivity of 600mV; input impedance of 180kohms; output impedance of 1.2 ohms; and frequency response of 20Hz-20kHz +/-1dB to full rated power. The Carissa's binding posts can be internally connected to the output transformers' 8- or 4-ohm taps. My sample was connected at 8 ohms. A 3-year warranty covers parts & labor, an optional passive volume control is available for $200. Standard power tubes are by Valve Art, but KR Audio equivalents may be substituted for an additional $500 - these upgrade tubes retail separately for $600.


My sample didn't come with the optional $500 active-convection glass chimneys and polished stainless collars [upper right] but did have a working heat sink -- visible below at the rear of the amp -- which is connected to the input transformer. Originally, this heat sink was implemented on all of Art Audio's higher-voltage models but isn't strictly necessary for lower-power domestic models built for 117V/60Hz line voltages. Nevertheless, it is available for $25 - about Art Audio's cost.


The Carissa measures 12½ inches wide by 19 inches deep by 10½ inches high when measured at the top of the output tubes. It weighs around 60 pounds and represents a real hunk of amplifier. In its polished stainless livery, it represents a beautiful hunk too, one that strikes me as a no-brainer even at its premium price. Construction and finish quality are robust and superb. Hardware used is first rate, two pairs of sturdy gold-plated brass 5-way binding posts -- just one pair per channel -- and two gold-plated, chassis-mounted RCAs. Of course the IEC power inlet is standard fare these days and invites experimentation with after-market power cords. Lastly, at the right rear of the amp is the power switch. There are no provisions for biasing - the amp is completely self-biased.


In his sneak peek, Srajan wrote "Considering its size, heft, power and detail work versus the other entrants of the line, the Carissa nearly screams loss leader." And it's true - it screams that loud and clear, something Art Audio's Joe Fratus verified as fact. Fratus told me that the Carissa has been introduced at a price that reduces their normal profit margin, in order to bring it within reach of those not previously able to consider this marquee. My advice is to not underestimate this amplifier based on its retail price positioning. This is nobody's entry-level amp.
What, a watt is a watt? Not!


Automotive enthusiasts know how there's more to engine performance than can be gleaned from its noted horsepower. Horsepower only tells so much of the story. There's also low-end torque to consider, and its ability to get a car off the mark. Then there's midrange performance, determined by the engine's power band which in turn is determined by where the torque peaks and falls off proportionally to where horsepower takes the baton and (hopefully) surges to redline.


But there's even more to a car's performance than can be gathered from the above. After all, the engine doesn't perform in a vacuum, isn't directly connected to the wheels but intermediated by a transmission. The transmission's gear ratios will determine how engine torque is best utilized. It's why a little four-banger can get off the mark almost as quickly as a much larger engine. After reaching cruising speed, the smaller power plant might even be able to keep up with its larger counterpart - as long as the terrain is flat. But a steep incline will have the little engine fall behind unless the driver gears way down. It just doesn't have the horsepower to keep up with the bigger motor.

Amplifiers are a lot like engines. They are the driving force in audio and mostly judged by their horsepower delivery (watts) but with little concern expended over torque (current). Neither do they operate in a vacuum. They require careful matching to a transmission (speakers) before there is music. You wouldn't pair a low-powered amplifier with a speaker that only came to life at high revs. Surprisingly, pairing a big amp with a high-efficiency speaker not requiring those high revs is no guarantee for performance either - unless it delivered high torque at low RPMs. A high-efficiency speaker may be far better off paired with a very small amplifier that maximizes its power delivery band within, not outside the speaker's usable range. In this case, current is at least as important as watts. Which brings me to the Art Audio Carissa, just one such amplifier. Judge its fortitude and brawn based on its relatively meager specs at your own peril. As they say, "it's not the size of the sword but the fury of its onslaught" [especially when the puny pen is said to be mightier - Ed.].

Where the rubber meets the road


When I read in Srajan's preview that I was expected to try the Carissa on my pair of Magnapan MG 1.6QRs, I thought he'd probably been out too long in the New Mexican sun. Everybody knows that the 1.6QRs require a big solid-state amplifier. Right? Well, not necessarily - but still, what affront to common sense.


Long story short, once I installed the higher-current KR Audio 845 tubes, I was shocked at how well the Carissa handled the Maggies. Sure, 16 watts of revving power limited ultimate loudness but the amp had the unexpected current delivery and torque to take the Maggies firmly in hand. Bass was surprisingly robust -- solid and tuneful -- and where the stock Valve Art tubes produced an upper midrange a bit too laid-back, the KRs snapped the Maggies back in line to sound splendidly neutral.


Naturally, nobody in their right mind is going to recommend the long-term mating of the Art Audio Carissa and the Maggies. I won't either. But the exercise -- as apparently intended -- aptly demonstrated that this is not your stereotypical prissy SET amplifier. It was but the first glimpse of what is so special about this plucky amplifier.


Art Audio claims that the Carissa is "a different twist on other 845 based amplifiers. Of course, the hand-wound split-core output transformers -- not usually seen in SET designs -- and power supply (designed by Art Audio's UK founder Tom Willis) are the secret ingredients." I'm told that a rethinking of what has been standard procedure in 845 amplifier design netted some noteworthy innovations. First, Art Audio lowered the input impedance at the output transformer to boost dynamics, clarity, and high frequency extension. Next, they eschewed tubed voltage regulation in favor of Mosfets. Last but not least, they significantly lowered plate voltage to 800 volts, doubling available current over traditional designs at the expense of fewer available output watts. Then there was the choice of 845 power triodes.


The optional KR Audio 845, said to be one of Dr. Riccardo Kron's last designs before his recent death, is, among other things, responsible for some difficulty organizing this review. I could easily have written an entirely separate review on the Carissa with the KR 845 installed - the difference between the Valve Art and KR tubes is that significant. But in the end, what makes the KR tube significant is that it shares the basic theme of the Carissa while taking it to another level. Though the Carissa with the Valve Art tubes installed sounds very different from the Carissa with the KR tubes, both share the same traits, just to different degrees. Everything about the Carissa is intensified through the use of the KR tube. If you like what the Valve Art-equipped Carissa is all about, you may be ecstatic about what the KR does. Or, you may not. The intensified bass of the KR could be too much for your room or your tastes. I can't imagine why, but you may not enjoy the added saturation of tonal colors and harmonics that the KR brings to the table, nor its added drive. But you do owe yourself an audition of the Carissa equipped both ways.


For the duration of the review, be mindful that I'm talking about the Carissa with the stock Art Valve tubes - but feel free to read between the lines, to infer that all positive observations were intensified with the insertion of the KR 845.