Conrad-Johnson CAV-50 Vacuum-Tube Control Amplifier

Conrad-Johnson CAV-50 Vacuum-Tube Control Amplifier
Jim Merod
26 April 1999


Power: [pentode] 45 watts/channel RMS into 8 ohms; [triode] 22 watts/channel RMS into 8 ohms;
Sensitivity: 500 mv to full power
Gain to PRE out: 20 dB
Phase (speaker outputs): non-inverting
Phase (pre-out): phase inverting
Frequency response: 20Hz to 20KHz +0, -.5dB
Hum/noise: 98dB below full power output
Hum/noise (PRE out): 94 dB below 2.5V output
Distortion (PRE out): less than 1% THD or IMD
Dimensions: 14D × 17.5W × 7.25H inches
Weight: 44 lbs.

Conrad-Johnson Design, Inc.
2733 Merrilee Drive
Fairfax, Virginia 22031
phone: 703/698-8581
fax: 703/560-5360

The Conrad-Johnson line of tube-based amplifiers and preamplifiers has been celebrated for its extraordinary fidelity to musical timbre and for its devotion to a maximum degree of seductive listening. Conrad-Johnson audio engineering is among the most respected in the often high-priced world of stereo equipment. If the art of listening is dependent upon good ears, good taste, and genuine intelligence, then the production of music worth listening to depends upon those exact capacities engaged with passion and precision at each point: by musicians, recording engineers, and producers. Superior playback equipment allows such values a chance to be heard. Bill Conrad and Lew Johnson have made a company dedicated to the beautiful but truthful reproduction of music. With the addition of the CAV-50 to their line, the C-J tradition is enhanced further.

Recently, integrated amp/preamp units have made a resurgence in the high-end community. The virtue of such integrated audio machines is immediate. First, you shrink the cost of owning an exquisite sound reproduction system if you choose a superior integrated unit. Second, you do not need to invest money toward a pair of possibly expensive cables to link your amp to your preamp since (voila!) the two are already connected in one box. Third, the best integrated amp/preamp combinations not only occupy less space in your listening set-up area than conventional two box systems; they promise the possibility for sonic transparency that otherwise is directly proportional to the vulnerable, sometimes problematic, “synergy” between two components. Magnificent sound is elusive. It is often closely related to cash outlay.

Krell has recently produced a solid state integrated unit that is priced very close to this tube-based powerhouse from C-J. On one hand, you might decide that the maintenance ease of a solid state system is preferable. Few people who are devoted to tube gear actually enjoy the time, cost, and trouble of replacing tubes. On the other hand, it is all but impossible to find a solid state amplifier or preamplifier that creates the warmth and richness of musical reproduction that is the benchmark of Conrad-Johnson products.

A word about this notion of musical “warmth.” Awhile back, I made an on location recording for an extraordinary trio of musicians. A very large tube microphone was at the center of the sound chain. A tube mic-preamp augmented the whole process. When the musicians listened to the playback, each of them commented on the “warmth” as well as the “detail” of the sound just recorded. In fact those two qualities, detail warmly rendered, were artifacts of glowing glass-covered elements that carried the heartbeat of their music.

Tubes have a potential musical magic that is undeniable. On this recording, the magic of these three musicians prevails. Each of them was in a wonderful personal place that conspired to lift their filled-to-capacity audience. Their delicate interplay as well as their provocative happiness are exquisitely obvious on the recording of that day’s venture. The sonic magic captured by tube microphones in a remarkable way matched the artistic magic of three musicians devoted for two hours to reworking majestic classics such as the Antonio Carlos Jobim songbook. The flow of their good vibes was sympathetically paralleled by the musical sympathy of the signal flow in the tube-gear they romanced as they transported their audience that sunny afternoon.

Technical papers have been written for sixty years or more to account for the musicality of vacuum tubes. Debates continue still, at increasingly refined levels of engagement, parsing the benefits of solid-state gear against those of tube gear. Recently, one finds advocates of each conceding that sonic differences between tube-based and solid-state amplification have decreased. Nonetheless, differences remain.

One hears by and large a greater degree of bottom-end control when the best (usually very large) solid-state amplifiers are driving the best (often very large) speakers. Few tube amplifiers can approach the authority of high-current solid-state amps in the lower octaves. But, in reverse, the refinement and liquid detail of mid-range harmonic information are rarely as beguiling — flat out convincing, especially with vocal and instrumental timbres — as the you find with the best tube amplifiers. I draw the distinction here not rigidly but as a tendency that has persevered in the world of audiophile experience with increasingly diminishing certainty of late.

Pushed to enumerate the precise dynamic and tonal qualities of this putative tube-generated sonic “warmth,” one enters into an endless conversation with others who care deeply about how sound is created on playback, and at its source. One enters, also, into an ongoing personal dialogue, a conversation (as it must be here) with oneself. The results are no doubt provisional and open to reinspection. “Warmth,” such as one finds it with the CAV-50, has many tonal shadings. This subtle quality might be better distinguished in comparison to the tube-based amplifier, the Audio Research “Classic 60.” Perhaps the comparison’s inexact nature is invidious since the C-J unit, after all, is an integrated rig while the Audio Research unit is a stand-alone amp. And yet the outcome of placing each unit in the “drive” position of your listening set up nonetheless carries a healthy measure of the very musical warmth under inspection here. The similarity is revealing. The differences are revealing, also.

Audio Research has never sought to convey the lush, sometimes larger-than-life sonic qualities of older Conrad-Johnson gear. I confess myself to be at once pleased and uncomfortable in the face of such seductive exaggeration. Let me be clear about the CAV-50. It has none of the over-the-top lushness one found in earlier C-J amplifiers. It is extremely honest in delivering the truth of signals fed to it. Audio Research, traditionally, has crafted gear that cleaves to a sense of sonic neutrality even at the expense of sounding lean, not fully rendered in the mid-band range just above middle-C on a large Steinway piano. The now vintage Audio Research SP-8 and SP-10 pre-amps compensated for such leanness by creating an ear-pleasing world that might be considered two versions (more extreme with the SP-10) of that elusive quality, “sonic warmth,” under survey here.

The sound of Conrad-Johnson and Audio Research tube-based amplification has grown closer over the years. And yet their sonic signatures remain distinct and evident. The Audio Research “Classic 60” is capable of rendering palpable details of voices and of the acoustic bass, in its middle to upper registers, that sound accurate as portrayals of the voice and the instrument and, also, feel accurate on an emotional level. Please understand this distinction. If you spend thousands of hours, as I have, recording music, you come to recognize a never unpuzzling truth: it is completely possible, in fact a frequent and repeated experience, to find yourself hearing music that you have recorded that SOUNDS right on playback — timbrally and dynamically accurate, et. al. — and yet that does not FEEL accurate. The curiosity there is that music at that moment does not convey emotional values that you are certain must reside on the tapes you’ve made.

When such dissonance between an apparently accurate body of sound and a somehow not fully accurate body of feeling appears, the first thing that one inspects is one’s own choice of microphones, cables, gear, and all the attendant choices of sonic capture that went into the recording. This is not merely a theoretical or a brief moment of crisis. It can truly mess up your whole day… or whatever part of the day that such dissonance remains. Thus, a recording engineer in search of full knowledge about his or her work will doubtless need several monitoring systems. One may rely on a main playback system and probably, in fact, should do just that for the sake of consistency of listening and control in one’s mastering and post-recording work. For the sake of one’s sanity, too.

But different monitoring or playback systems give you a different “look into” the sound stage you have attempted to catch sonically. Such “catching,” of course, is always a fabrication — a creation (or re-creation) of what the engineer believes is “there” to be rendered, to be held for posterity as the recorded “truth” of an event. This attempt to catch what is genuinely available — in and of itself, on its own sonic terms — is true for studio recordings to a degree but, I think, it is more massively the case with on-site recording work, especially when it is accomplished direct to two tracks.

Thus, an engineer needs to carefully monitor recorded work from several perspectives in order to comprehend as much as possible about its sonic details. No less important in the end is an understanding of the emotional truth that resides within those details. Over the years, I found the “Classic 60” to have a useful productivity for my own monitoring because, even though it is not the final arbiter of sonic detail, its considerable clarity embodies the emotion of the music it conveys. I might note here that, for the sheer drunken pleasure of listening to the lush overcharge of musical warmth without this useful degree of sonic accuracy, the circa-’70s Audio Research D-76a is a technicolor delight. In contrast, the “Classic 60” provides a strong sense of instrumental tangibility and delivers you to a coherent understanding of recorded masters — a coherence, finally, made possible because you have a vivid sense of the music’s intrinsic emotion. Music, ultimately, is emotional meaning more than it is a collection of elements of sound and notation and performance. Music is emotional meaning as and how those elements comes together.

Now the point of looking at the “Classic 60” alongside the CAV-50 comes to this: few amplifiers I have ever heard achieve that useful combination of a potentially analytic “look” into the music’s spatial and sonic details together with an emotionally convincing “feel” for its lyrical and human meaning. I am certain that I am unaware of amplifier/preamplifier combinations that, in tandem with the right speakers, accomplish such sonic accuracy and emotional involvement.

But the new Conrad-Johnson integrated amp delivers this balance in spades as I pursue its secrets. For a recording engineer, that is a virtue that amounts to an elusive, complex necessity. If you imagine that I admire the CAV-50, you are correct. If you believe that I hear it to be quite similar to the “Classic 60” you read me wrong. The Audio Research amplifier is fuller in its delivery of dynamics, richer in its sense of musical palpability, and softer, more subtle in its tonal and timbral shadings. The Conrad-Johnson integrated unit is quicker in its delivery of mid-range transients (not those at high dynamic levels and certainly not at high volume levels). It is somewhat leaner and more precise in its rendering of images. With the CAV-50, a vocalist’s physical placement is distinct and explicit. With the “Classic 60” it is larger, rounder, fatter, but not so vividly “in place” spot-on as an event within a body precisely rendered in its soundscape.

This notion of emotional understanding does not stand at odds to one’s comprehension of sonic details. In fact, I’ll assert that the difficult-to-define value of sonic “warmth” in some no doubt imprecise ways, underlies both the understanding of what the ear understands and how that translates as feeling (or emotional meaning). That is the case, I think, because such warmth is not so much a value (essentially) imparted to sound by the amplification of signals as it is a value within sound itself that some amplifiers convey convincingly — with restraint and a useful degree of ear-opening intrigue.

Let me say, parenthetically, one more word (never conclusive) about sonic “warmth.” If you were to employ on a recording project a large-diaphragm tube microphone such as the Groove Tubes 2a, or the new Audio-Technica 4060, several qualities are sure to confront you. One is the difference between the two microphones. They are both splendid. Each, used with care and close attention, captures the sound of a large Steinway piano, for example. Both microphones have the ability to render its enormous authority throughout the sonic spectrum. Both microphones are “transparent” in the exact sense that, on recordings using a pair of either one, the piano will appear with force and command as those qualities appear to your naked ears at a good vantage point in a live performance. We realize, of course, that no recording captures exactly and completely what the live experience holds. But the illusion of “life” is similar with these microphones used in the right way. It is not the same precisely, but nearly so. Their differences are fragile and vastly interesting.

Those differences reside primarily with subtleties of transient attack and decay. On occasion, and this frequently depends upon ambient surroundings that frame a recording venue, the sense of “heft” or “slam” that defines the essential power of a good piano during recorded performance may be altered by inherent timbral differences (resulting from capsule design, of electronics, of elements; et. al.) that distinguish two superior and in many ways similar microphones. Something very hard to describe, in part measurable, yet nonetheless outside the precise scope of linguistic and numerical description, differentiates the capture of such pianistic authority — its heft, slam, tonal truth and balance: its micro-details and its very “thereness” as well.

Different microphones gather all that in “transparently” and truthfully it seems, but with tonal resonances that you can designate by recognizing what part of the sonic spectrum each prefers, or emphasizes; which it is shy to gather in, and where the roll off points appear at the top and bottom of the sound spectrum. [The A-T 4060, for example, is flatter through the majority of the spectrum than the Groove Tubes 2a, while the later mics capture a greater sense of transient fullness, of sonic width and depth.]

One of the differences to be noted there, finally, may be registered by this fleeting quality that one designates as “warmth.” A piano may be captured quite beautifully and accurately and still sound “dry” on playback. When the accurate capture of an instrument or ensemble carries a relaxed fullness of delicate sonic details, sometimes (not always) one is tempted to ascribe that to a “warmth” that pervades the sound. Good music heard well in a splendid acoustic environment does, by and large, carry a sonic warmth that does not call attention to itself as a separate detail. It is simply and inherently a condition of music heard with satisfaction. In this inflection, sonic warmth can be directly related to what I will call musical or notational “bloom.” It is in part defined by hang time (appropriate lingering or resonance) in the appearance and decay of notes. When a microphone, or an amplifier, creates a sense of that “warmth” it delivers musical sound that “feels” to the ear as if it is somehow palpable, real, and gloriously within the actual physical reach of the listener’s alert attention and pleasure.

In its ability to translate the power and delicacy and meaning of music, the CAV-50 is superior. The CAV-50 owns a warmth of sonic delivery that is real, unobvious, and convincing of musical truth and authority. It helps a recording engineer hear what is on recorded material. It does so with analytic precision enhanced by emotional life and verve. The unit is constructed like a well-built safe. It is a brilliant piece of audio gear whose sonic signature is defined by what I will call a subtle, warm transparency. I have listened to the CAV-50 — or through its wonderful huge sonic aperture — for dozens upon dozens of hours. I have listened to solo voices, solo guitars, piano trios, saxophone/piano quartets, eighteen-piece big bands, mid-sized ten-piece ensembles … whatever is on a recording is what you hear in return without the sense of detachment (however elegant that may be) that sometimes accompanies more analytical amplification and pre-amplification line stages.

In the end, words cannot designate sonic values that differentiate gear at this level of resolution and magnificence. Therefore, as a way of surrounding my quarry, let me stumble forward to put the Conrad-Johnson CAV-50 into one more comparative perspective. I have been listening for nine months to a pair of European monoblock tube amplifiers that cost exactly ten times the amount of this integrated musical box. The huge power supplies in the expensive amplifiers, and both the size and number of the tubes at work there, give the European amplifiers a considerable edge over the smaller integrated C-J amp/preamp.

I love the big tube monoblocks. They are exquisite. But, if the ability to engage a listener, and transport the music lover’s heart to an inspired lyrical place, is the essential mark of great audio equipment, then this mighty, downright attractive CAV-50 “vacuum-tube control amplifier” from Conrad-Johnson is a giant in disguise. The essential sonic difference between the huge monoblocks and the much more modest yet still hefty C-J unit is, in the end, relatively small. The two are close in spirit. You may not have the sublime authority that the big amps provide, but you will enjoy music not a jot less with the CAV-50. It is one of those glorious audio devices that keeps you putting on favorite recordings, one after another.

Comparisons are burdensome. The outcome of time well spent with the CAV-50 is absolute pleasure. This is a gorgeously-designed, well-priced, and wholly flexible amp/preamp combination. It is rated at 45 watts/channel RMS into 8 ohms in its conventional pentode mode. The unit can be reconfigured for triode use at 22 watts/ch. RMS into 8 ohms (an alteration I have not yet pursued). It has five pairs of RCA inputs plus an external processing loop (in and out) as well as a pre-amplifier “out”. At a retail price of $2,495 the CAV-50 is within reach for many who want and need a spectacular upgrade at the heart of their listening system. This is a unit that will not disappoint you. It is not just another fine piece of well-crafted audiophile gear. It is musical. It is a friend to good music and to those who love music.

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