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SE-84C Zen Tube Amplifier

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se84c tube amplifierThe Amplifier Scene

Half-a-century ago, supposedly in reference to driving his hundred-some-dB-sensitivity Cornwall, Paul Klipsch said, “What this country needs is a good five-watt amplifier.” What Mr. Klipsch probably didn’t anticipate were the commanding prices of some of today’s five-watt amplifiers.

In the vacuum tube amplifier family, the single-ended triode tube amplifier is the much celebrated and infamous member. However, the prohibitive cost of some triode tube amplifiers, especially those of the 300B variety, can represent a high maintenance cost when the time comes for tube replacements.

During the 60’s, the dawn of the transistor was to revolutionize audio amplification with its lower cost of manufacturing, ease of maintenance and measured excellence, making powerful amplifiers increasingly affordable to the general public. Taking advantage of such new technology, speaker designers considered the transistor phenomenon a newborn freedom in their endeavor, according them unprecedented flexibility in design parameters previously impractical because of scarcity of power. Continuing and reinforcing the trend to this day, makers of both amplifiers and speakers churn out amplifiers of brute force as well as inefficient speakers.

Considerable advancements over the decades in solid-state amplifier design notwithstanding, many tube aficionados still prefer the century-old tube design because of its more sonically benign, even-ordered harmonic distortions when pushed to the limit as opposed to solid-state’s predominantly odd-order harmonic distortions, which many claim to be more sonically detrimental. Objectively speaking, both solid-state and vacuum tube amplifiers possess distinctive sonic signatures that delight every audiophile; but neither design combines the advantages of perfect linearity with power and stability to boast. Therefore, speaker efficiency concerns aside, it becomes largely a matter of taste in choosing between a solid-state or tube amplifier.

Decware & the Zen Amp

According to the Merriam-Webster Dictionary, Zen is a noun for a Japanese Buddhist sect that teaches self-discipline, meditation, and attainment of enlightenment through direct intuitive insight. Historically, the Japanese Zen was a derivative from the Chinese original with the same basic meaning.

Greg Weaver pointed out to me that Nelson Pass first adopted the Zen designation for amplifiers during his bygone Threshold era. With the single-ended topology being the commonality of Decware and Threshold, in the company of esteemed manufacturers like Audio Note and Cary, Decware applied the topology to the simplistic tube circuitry in the design of his Decware products. Nelson Pass, currently with his technology-intensive Pass Lab equipment, continues to flourish in his solid-state arena.

When you visit Steve Deckert’s Decware website, a program begins to run and a passionate female voice greets you. The current products include the $499 Zen triode SE84C, the $695 Select SE84C-S, the $1495 Zen Triode Dual Mono Integrated SE34-I, the top-of-the-line $1995 Zen Signature triode monoblocks, the $795 Zen Triode Phono Stage ZP-1 and the $895 Zen Signature triode preamplifier. Being the joy and pride of Steve, his miniature SE84C Zen Triode Amplifier is aesthetically a bare-looking, minimalist design measuring 6 inches wide, 10 inches deep and 6.5 inches at its tallest. Sitting on four little rubber feet, its unimposing size looked lonely on a shelf and hardly called attention to itself.

The SE84C features the cheapest and smallest output tubes I’ve ever known, the Svetlana SV83. $7 each, two SV83 output tubes are configured to produce a claimed 5 Wpc into 8 ohms. The owner’s manual recommends annual output tube replacement. The rectifier tube and input tubes are said to be able to last for many years.

There are altogether eleven hand-to-hand wiring solder points and no circuit board. Only one capacitor and two resistors are in the signal path with no hookup wire. One surface-mounted bias toggle switch on the front and one rear-mounted power toggle switch are provided. Although the switches are not labeled, the simplicity of the SE84C’s operation makes the use of them quite intuitive and self-explanatory. I prefer switching the bias toggle towards the amplifier’s rear because that produces higher output resulting in better dynamic contrasts. A bare rotary volume pot on the rear completes the functionality. The power cord is detachable, and only RCA inputs are facilitated. Two very sturdy sets of surface-mounted three-way speaker binding posts are provided.

Decware boasts in the owner’s manual that:

“it is usually a given that no other part of your hi-fi system is capable of surpassing the fidelity of the SE84…You would have to spend around $10,000 on a cost no object front end to actually hear the fidelity this amp is capable of…you will never be able to actually hear the amplifier, it only passes signal (no coloration’s) so whatever you feed it is what you’re going to hear.”

Assuming “fidelity” means honesty to original signal, then it is safe to say that a component with the highest level of fidelity is one imparting no individuality at all – a component you cannot hear. So, I agree with Steve on the perfect amplifier definition.

What I disagree with, however, is the statement that says it take a $10,000, cost-no-object front end to hear the Zen amp’s level of fidelity. A perfect amplifier would amplify signals from upstream components with no coloration or distortion, whether those components are sonically superior or inferior. What Steve might have meant to say was that to expose any sonic contamination induced by his Zen amp, it will take the most transparent equipment in the audiophile marketplace usually carrying a price tag of $10,000 and upwards. We shall see.

Set Up & Audition

SE84C’s built-in volume control was initially used as the only means of level setting, whether I was playing SACD from my Sony SCD-777ES SACD Player, or Redbook CDs from my CEC TL1 belt-drive transport via Illuminati Orchid AES/EBU cable to Wadia 27 Decoding Computer. In the case of the Wadia 27, its output was internally reset at the same level of the Sony SACD player at 2 V, churning out maximum resolution and volume. Without a preamp, the Zen Amp’s volume pot was consistently rotated to approximately 75% of full volume to reach my preferred listening level. Cables used are the Granite Audio #470 throughout, with Cardas Quadlink 5C speaker cable. Speakers were my 104 dB Klipschorns.

Beginning with no preamp, I played SACDs first to get an impression of the resolution attainable via the Zen amp. The first disc I chose was Mark Levinson’s “Red Rose Music Sampler” Super Audio CD. Recorded mostly inside the small studio of the infamous Manhattan “Red Rose” store, this SACD highlights sounds of single instruments primarily.

Despite the SE84C’s modest output, it allowed the Klipschorns to depict the instruments without sounding constricted or uninvolving. Honestly conveying the bare ambience of the studio, the Zen amp conveyed a surprising proliferation of tonalities at the same time, drawing my attention to realism of instruments like guitar, saxophone and piano, which contained revealing overtones, endowing the sound with body and character.

Initially, the Zen amp reproduced convincing dramatic contrasts from the Sony Classical SACD”The Rite of Spring [Sony SS 089062], until sustained levels of snare drum rolling progressively caused clipping distortions. In addition, a slight touch of dryness surfaced during louder passages, while the background tape hiss of the vintage master tape was notably audible during softer passages. Neither of which was as prominent when amplified by the Audio Note Quest Monoblocks. On the bright side, the Zen amp disclosed a sheer amount of information in terms of spatial definition and instrument tonalities.

The clipping distortions became far more prominent when the Zen Amp was asked to reproduce the hellish drum strokes from Verdi’s Requiem [Sony SS 000707]. With the AN Quest, this extreme orchestral bottom-end rendition epitomizes a frighteningly surreal afterlife or judgment-day experience. In the case of the Zen Amp, it portrayed the ambience well with realistic spatial definition; but the soundstage collapsed momentarily during demanding peaks. On audiophile grounds, this SACD has startling clear dimensionality and highly definitive drum strokes over the regular CD version. It is a wonder those archaic studio master tapes can preserve such powerful passages.

Pianist Vladimir Horowitz’s reading on SACD Horowitz [Sony SS-6371] was one of awe and dimensionality via the SE84C-driven Klipschorn. A sense of ease and realness complimentedthe string hammering, as fortissimos and pianissimos carried seemingly infinite contrasts of dynamics. Despite the periods somewhat less opulent recording quality compared to today’s standards, it easily exceeds Redbook CD versions of the same repertoire in its drama and power.

Playing regular CDs via the CEC TL1 and Wadia 27 combo, the soundstaging of Richard Strauss’ An Alpine Symphony [Deutsche Grammophon “Karajan Gold” DG 439 017-2] was at once wide and stable, with a spellbinding coherency throughout, reinforcing both the label’s and my K-horn’s consistent traits. However, in addition to the thunderous bass drum in track 19, “Thunderstorm, Descent,” which quickly depleted the Zen amp’s dynamics and soundstaging abilities, a touch of coarseness persistently exerted itself. Despite that, Maestro von Karajan’s Germanic discipline and pitch perfection were communicated admirably. It was like staring into the cleanest water at a beach and being able to see the movements beneath. Only during sustained intensity did it again show a loss of definition in dynamic transients and timbre portrayal.

Performing the vocal version of Samuel Barber’s “Adagio For Strings”, renamed as “Agnus Dei”, the Corydon Singers under the baton of Matthew Best from Bernstein Chichester Psalms [Hyperion CDA 66219] produced some of the most hauntingly anointed and euphonious vocal effects – as rendered by the Zen amp. Despite the lack of midrange silkiness from this early digital recording and the hint of coarseness, there was immense musicality that spoke volumes of the composer’s ingenuity. Fortunately, absence of an orchestra both alleviated the load considerably and complemented the light character of the Zen amp.

Wilhelm Kempff playing Beethoven’s Moonlight piano sonata [Deutsche Grammophon “The Originals” Klaviersonaten CD 447 404-2] was incomparably rendered, as the Zen amp immaculately resolved the German pianist’s hammering of the strings with incisiveness, sonority, and an abundance of ambience. While the sound didn’t approach the resolution of SACD, the music playing was rendered with precision and control.

The singing of Ella Fitzgerald [Best of Ella Fitzgerald & Louis Armstrong, Verve 314 537 909-2] emerged as velvety vocal renditions with excellent reverberation. Armstrong’s trumpet smearing in “Summertime” was given amazing definition by the SE84C’s ability in low level detail retrieval. While the trumpeting was given adorable depiction, the magnetism in Fitzgerald’s voice was lightly tainted by a touch of dryness.

Changing to my stereo Monarchy Audio SM70 produced more pronounced dynamic contrasts from the same passages, rendering the sound livelier and more energetic. This energy was most captivating even in music featuring solo instruments. The higher 25wpc output of the SM70 also enabled it to convey full orchestra passages without impediment, a task with which the SE84C struggled. The SM70 also induced increased top to bottom-end responses. However, in spite of its strengths, the SM70 couldn’t approach the instrument tonality of the SE84C.

Playing the same passages, adding my Krell KRC-2 solid-state preamplifier increased the SE84C’s dynamics at the expense of even more pronounced coarseness. Although the soundstage width did not diminish, the onstage activity portrayal turned slightly chaotic, making the presentation slightly tenser. Audio Note’s M3 tube preamplifier largely eliminated the Zen amp’s coarseness and promoted even more coherent tonal shadings among activities onstage. However, the Zen amp also displayed dynamic strains more often with the M3 reigning. A pair of the SE84C’s, run in monoblock configuration, may further improve the dynamics and should be something to consider, given their affordable pricing.


I expect that Steve Deckert will not agree with my description of the sound of his Zen amp; but the Zen amp’s fundamental lack of tube smoothness and transistor-like tonalities puts it in a different league than typical tube amplifiers. Despite the noticeable bottom octave deficiency in the playback of selected music, my K-horn’s lifelike dynamics were largely unimpeded as driven by a single SE84C. Solo instruments and light jazz represented easier loads on the Zen amp and were wondrously revealing. Bass drums in complex orchestral pieces, however, were deprived of definition summarily.

Depending on your sonic priorities, extensive auditioning of the Zen amp may either boost your passion in the audio hobby, or prompt you to throw the little dwarf out of the window. The Zen amp’s real commendable quality, no doubt derived from its lack of complex circuitry, was its highly passive nature, resulting in an unusual susceptibility to changes in system matching. This easily makes the Zen amp the singular most uncompromising piece of equipment in a system given its unpredictability. While the Zen amp may well be the theoretical ideal to many audiophiles, this fundamentally passive character demands proficiency in system matching and ultimately may not bode well with audiophiles with determined sonic preferences.

It is necessary to have clear sonic priorities to put the strength and weakness of the Zen amp into fair and proper perspective. Theoretically, equipment similarly devoid of character should compliment the Zen amp; but discretion must be exercised in such pairings. Be mindful that, in spite of the claims of transparency or fidelity, products from different companies do sound different. What the Zen Amp needs is compatibility, a budget companion component like Steve’s $895 Zen Signature Triode Preamplifier, which is presumably designed with the same approach and priorities. If so, then they may make a potential pairing mandate. The SE84C is unable to compete, power-wise, with other amplifiers of either tube or transistor variety; but for readers possessing efficient speakers who prefer to have a minimalist and sensibly-priced reference, its $499 MSRP represents essentially an automatic recommendation.

The SE84C is mechanically reliable, economically priced, physically unobtrusive, cheap to maintain, and above all, it provides a bold statement of what a cleverly put together and affordable machine using conventional methods can do. Objectively, the Zen amp is a conceptual triumph. It is pure in nature and essentially maintenance-free. Subjectively, its very limited driving capability and a distinctive departure in sonics from the mainstream norm for tube amplification debit it. Longstanding 300B tube users may not appreciate the Zen amp’s unique fundamental traits, and audiophiles accustomed to transistor powerhouses may never find the SE84C worthy. Retrospectively, however, to some ears, the SE84C’s ability at tonal precision and ambience depiction can be gratifying.

Amidst a world of diversity in designs and implementations, all high-end audio companies past and present claim the title of maker of the best sounding equipment. The truth is, despite the claims of fidelity and transparency by various companies, with all their experiences and advanced understanding of the technologies involved, no two company’s products will sound the same. Therefore, I find Decware’s proclamation of its products superiority by recommending the SE84C for use with cost-no-object machines, both bold and subjective.

Many readers are firm believers in technological advancements and in constantly staying abreast of the latest offerings by actively buying new equipment and trading in their old pieces when they are discontinued. Many amplifiers will bring these financially well-endowed audiophiles and music lovers to musical nirvana in flamboyant style. The SE84C, in its simplicity and appearance, may not bode well with that group.

At $499, the SE84C upsets the established value versus price ratio in our hobby and warps our perspective. It requires neither significant soul-searching nor deep pockets to acquire this amp, but its output limitation may hinder matching to most audiophiles’ systems. Therefore, this Zen amp will be appreciated only among audiophiles with high efficiency loudspeaker system. And, just like one may have bought an Acura NSX but not an equally fast Mazda RX7 for less than half, and the folks who can afford Mercedes Benz and BMW will unlikely buy a Honda or Toyota. Yet the birth of the SE84C is a brilliant and necessary step in the audio evolution. Products like the Zen amp seldom get recognized, especially when they are this affordable.

By adopting the affordable SV83 as the main output tube for critical audio applications, the emergence of the Decware SE84C Zen amp is a cause for celebration. Even without further enhancement, this is one affordable high-end amplifier worth owning. It should be experienced.

Manufacturers Comments:

Audio is a fine balance of compromises. The Zen was designed to sit in the peak of the Fidelity vs. Power curve I frequently talk about on our web site. It excels in the things I personally feel are important which is of course a subjective call.

The goal with the Zen Triode was to reach modest listening levels in apartment type systems. On efficient speakers it is possible to fill much larger rooms.

K-Horns are a bittersweet match with a single Zen. The SE84C does not care for complex crossover networks such as those employed by the K-Horn. The K-Horns are so efficient that you’re able to drive a pair to substantial levels before it gets ugly. In fact the sound is so convincing that you are literally teased into asking more of the amp than it has to give.

On the other hand if you have a Lowther or similar single driver design around 98dB without a crossover you can actually play at a level that significantly exceeds what is possible with K-Horns at 104dB.

Since these amps can be bridged without the typical smearing that can occur in other bridged stereo amps, it is a cost effective solution when you need more power. The Zens put out more power as the impedance drops so you can expect to net an increase of almost 6dB when you bridge a pair of them.

As far as the review goes, I am impressed with care and skill that obviously went into writing it.

Steve Deckert
Decware / High Fidelity Engineering Co.

Associated Equipment:

Digital Front End
47 Laboratory 4715 Flatfish CD transport & 4705 Progression DAC
CEC TL1 CD transport
Sony SCD-777ES SACD/CD player
Wadia 27 Decoding Computer

Audio Note M3 preamplifier
Audio Note Quest 300B monoblocks
Decware SE84C
McCormack DNA-1 Deluxe
Music Reference RM9 II

Apogee Duetta Signature
Audio Note AN-E/D
Celestion SL700
ELAC 518
Genesis VI

Audio Note AN-La (8 feet, bi-wired)
Audio Note AN-V silver cables (RCA 1m, 2 pairs)
Aural Symphonics AS-One (RCA 1m pair, 0.5m pair)
Canare L-5CFB 75-ohm digital cable (RCA, 1.5m)
Canare D206 110 ohm digital cable (AES/EBU, 1.5m)
Cardas Quadlink 5C (8feet)
Granite Audio #470 silver cables (RCA 1m, 2 pairs)
Granite Audio #560 AC Mains
Illuminations Orchid (1.5m, AES/EBU XLR)
Illuminations D-60 75 Ohm digital cable (1.5m, RCA)
Van den Hul MCD-352 (8feet)
Wadia ST glass fiber (2m)

Salamander Synergy 20 (2)
ASC Tube Traps
Flat Traps

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One Response to SE-84C Zen Tube Amplifier

  1. daniel gustavo pace says:

    Very nice.
    i would like to have one in my audio system.

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