conrad-johnson ART27A stereo power amplifier

Tubed power amplifiers
Conrad Johnson ART27A

The downside to the high-grade component roll-out is those PTFE capacitors are notorious for needing an almost eternal run-in. Fortunately, the ART27A circuit doesn’t seem to mean that has good days and bad. Instead it starts out good and matures with age. In pure listening terms, the cynical have argued that those caps only really show what they are made of by the time you wear out the first set of valves! 

Low power, Class A triode-coupled or single-ended power amplifiers are meant to be used in conjunction with high-sensitivity (efficiency) loudspeakers in order to reward the listener with a, somewhat unrealistic, but nevertheless, subjective impression of being able to reproduce even the most complex musical material with no strain and ample (subjective) dynamic and resolution headroom. And, as Jeff Fischel, contemporary top-dog of conrad-johnson likes to add – in small to medium size rooms of up to 25 sq.m. Lo and behold, so it may be, but we decided to put the ART27A to work in considerably more laborious conditions. Why? Because only if you push something close to or beyond the limit, you may be able to realise the actual true potential of the device under test. So, the ART27A had to, for the purpose of this review, deliver in a fairly large room and connected to loudspeakers of no particular high sensitivity (under 90dB) and of very serious demands in every imaginable respect. Demands that even power amplifiers delivering hundreds of watts of undistorted power would not necessarily meet.

The bottom line is that the ART27A admirably sailed through all the pieces of less and more complex musical material it has been exposed to and returned a very confident and stable sound. It did this at unexpectedly high volume levels without running out of steam, compressing the natural dynamics of any of the music it processed, without even softest trace of clipping. Precision, purity, palpability and poignancy would be a quartet of suitable attributes combined with a highest degree of 3D soundstage rendition, superb musical transparency and, above all, musical clarity and transient speed only Class A circuit design approach can possibly give.

Let us, however, travel back to reality for a moment. Two crucial qualifying statements about the ART27A before misconceptions creep in. When combined with the very best high sensitivity loudspeakers of suitable size and used in rooms of appropriate dimensions, ART27A will play any type of music as loud as you wish with total confidence, stability and guts. From a small combo to any of the Mahler or Bruckner symphonies. If used in any other way, it will sound at its best even if the speakers and environment in case may not suit it ideally, for as long as combined with equally capable or superior other members of the audio system in use, its limitations (because of the relatively low power output) will reach up to, let’s say, “early Beethoven symphonies at any level.” Above all else, it retains musical complexity at reasonably high levels with total comfort and ease.

The overall sonic signature of the ART27A can be defined as “realistic musical precision”. That means an even tonal balance with a very broad midrange covering beautifully what is contained within most music. Treble is sweet and extended without being glassy, while anything happening below 50Hz or so maintains control and sufficient amount of body without starting to wobble or lose coherence as power may become in a somewhat shorter supply. Most importantly, the whole spectrum is successfully integrated into a harmonious entity serving well any genre of music. In a way this is approaching the best of both the solidity and presence of traditional push-pull designs, with the lithe, liquid and languid sound of single-ended. 

Depth, width and height of the soundstage are remarkable, most likely owing to the Class A operation and, as some would say, not too many Watts.

I have been deliberately circumspect in the nature of the music played here because the ART27A is uniquely well placed to play everything it receives with equanimity and poise. I’m probably not the biggest proponent of Black Metal or Japanese Death Jazz (although I do have at least one disc of both genres in my collection), I’m confident that the ART27A would make an equally good fist of both of them, then turn its hand to Ukrainian folk, then disco, then throat singing without turning a hair. Best of all, enthusiasts of all these genres and more would look to the ART27A as the amp best suited to play ‘their’ music. And that’s perhaps the great joy of the ART27A; it’s the amplifier for people who want that great audio performance found in products elsewhere in the c-j stable, but who want an immediacy to their music too. 

An amplifier that is insensitive to types of music should also be most likely very versatile for use in a wide variety of systems, the ART27A is a just as accomplished in every imaginable respect as any other c-j power amplifier, with added bonuses for a very, very high degree of detail, articulation and transparency with absolutely no loss of the traditional and ever improving c-j musicality magic. Even without enough power for some, the ART27A is very much a justified resident of the new reference standard department within the c-i pyramid.

That all being said, the question of components in front of and behind the ART27A is a pressing one. You don’t use a reference standard preamplifier with baseline and entry-level components, and the conrad-johnson power amplifier is sufficiently resolving to insist on the best. There is a natural partner in the conrad-johnson GAT S2 line preamplifier, of course, but to get the most out of this power amplifier you need to be willing to use a product with that kind of performance abilities. You could make a similar assumption about source components, cables and equipment supports; this product delivers a top-notch performance and demands the same of the components to which it connects. 

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