Decware SE84C Zen Triode Monoblock Amplifiers

Decware SE84C Zen Triode Monoblock Amplifiers


Constantine Soo

17 December 2002


Output: 5 Watt, stable into 2 ohm, zero negative feedback
Frequency Response: 25 Hz – 25 kHz (+/- 3 dB) 30 Hz – 20 kHz (+/- 1.5 dB)
Hum and Noise: less than 1.5 millivolts
Input Impedance: 100K
Output Impedance: 0.8 ohms
Dimensions: 6″ W × 10″ D × 6.5″ H
Weight: 10 pounds
Price: $499 each, fully assembled factory direct/$399 kits
Warranty: 30 years to the original owner

Decware/High Fidelity Engineering Company
1202 N.E. Adams Street, Peoria IL, 61603
Phone: 309-671-2428

Continuing the Journey

In my earlier look at the Decware SE84C Zen Triode amplifier, I examined and recognized the petite amplifier’s subtle but efficacious tonalities and excellent contrasting dynamics during low to medium volume levels in the company of the Klipschorn. Still, the persistent dynamic compressions and loss of soundstage coherence during higher listening levels reflected its unsuitability to drive most speakers. Thus, I concluded with the speculation that a pair of them in monoblock configuration would probably be the more realistic option. 

Disagreement from Steve Deckert’s customers surfaced in the Decware online Forum, and I responded to one reader’s opinion in the following abridged excerpt:

“I might have been exerting overly demanding expectations upon the Zen Amp. Yet as a reviewer, I believe I have attained the task of scrutinizing the product under review to the best of my ability. And to summarize and answer your last question, while the SE84C has impressive merits in its design, for the merits and shortcomings of its coupling to the Klipschorn, the single Decware/Klipschorn was not an ideal combination playing music to my expectations, leading me to believe neither will it be for the average room/listener.”

As I further my investigation of the Decware SE84C in monoblock configuration, allow me to reiterate Steve Deckert’s claim as outlined in the Owner’s Manual.

“…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.”

Monoblock Operations and System Details

The second SE84C Zen amplifier Decware sent me was also pre-wired in the standard stereo mode. Users can reconfigure the units to monoblock operation by following 2 steps clearly outlined in the Owner’s Manual. 

The first step entails strapping each SE84C’s left negative speaker output to its right positive speaker output via a single jumper cable. I used my banana-terminated Van den Hul MCD 352 speaker cable for the reconfiguration strapping. The speaker cable then connects to the left positive and right negative terminals. 

The second step requires that the left channel output from the preamp be presented to both the left and right inputs of the newly reconfigured left monoblock, and similarly, that the right channel output from the preamp be fed to both the right and left inputs of the newly reconfigured right monoblock. Although the Manual suggested the use of a Y-adapter to facilitate this, I made use of theAudio Note M3 preamplifier’s two pairs of RCA outputs to accomplish the task.

Once put into operation, I found the second SE84C to have roughly 10% lower maximum output than my own unit, necessitating judicious volume matching. Thus, for the duration of this review, I set the new SE84C to maximum output while lowering that of my unit a little. Also, the second speaker binding post polarity arrangement was curiously the reverse of my own unit on the second SE84C. 

Since the last Decware Review, the 47 Lab Flatfish/Progression digital system has replaced the CEC TL1 belt-drive transport and Wadia 27 Decoding Computer system as my presiding CD reference, taking the helm with my Sony SCD-777ES SACD player. 

Audio Note’s double conductor 99.99% litz copper screened AN-La served early on as the main speaker cable, with its own single conductor 27-strand 99.00% litz silver SPx and Virtual Dynamics’ Nite speaker cable providing additional insights. 2 pairs of Granite Audio #470 silver interconnects performed the connections from the M3 initially, with VD’s Nite interconnects taking turns afterwards. 

In order of efficiency, the Klipschorns (104 dB/8 Ohm), Audio Note AN-E SEC Silver (94 dB/8 Ohm), Loth-X BS1 (94 dB/8 Ohm) and Genesis VI (90 dB/6 Ohm) were used to evaluate the Zen monoblocks. 

The new SE84C went through a minimum of a 60-hour burn-in period before the audition began.


The first set of speakers I paired the twin SE84Cs with was the Klipschorns, and I promptly started off with the first classical SACD release from Deutsche Grammophon, Beethoven Symphony No. 9 [DG SACD 471 640-2] and Sony Classical SACDs The Rite of Spring [SS 089062] and Requiem [SS 000707], all at breathtakingly high volumes. This time, I am glad to report that I was not able to reenact my negative experience related to one Zen in stereo operation. Dynamic compression was all but eliminated, and the hellish snare drums from Verdi’s Requiem landed thunderously through the 15-inch bass of the Klipschorns, attesting to the dynamic compatibility of the match. For the record, a half past 9 volume setting on the M3 was already loud enough due to the K-horn’s superior efficiency.

The coupling also possessed microdynamics that helped to preserve the DG SACD’s inherent subtleties in instrument depictions during passages of all magnitudes, diligently reflecting the DSD-processed medium’s finer texturing and delicacy over the Redbook CD edition. Despite a residual violin coarseness typical of DG’s analog masters of the 70’s, the DG SACD offers the first high-resolution presentation of the Ninth that is deeply rooted in the finest classical tradition with interpretation authority and sonic might.

Whitney Houston’s soaring voice in “I will always love you” from theBodyguard soundtrack [Arista 07882-18699-2] came through with a highly potent mixture of body and dynamic transients. The Decware/Klipschorn system showcased Houston’s incomparably adaptive and elastic vocals with both tender delicacy and festive vibrancy. There was also a meticulous retrieval of dynamics from the vocalization and instrumentation, as the supporting band was heard in contrast to the singer in discernible clarity without the slightest suppression of vocal cues. This song represents pop singing at its best and continues to raise goosebumps after all these years with its rare combination of expertly and spontaneously exercised singing in both subdued and liberated manners, complimented breathtakingly by lyrics of passion and sacrifice. 

Trumpeter Tiger Okoshi’s 20-bit K2 CD Two Sides To Every Story [JVC 2039-2] also validated the twin-SE84C coupled Klipschorn’s dynamic competency with a rendition of the trumpet’s soulful liquidity and incisive spontaneity in “Yesterdays.” Despite a less vivid tonality and simpler texturing when compared to the solid-state 47 Lab Gaincard S, the Zen induced from the Klipschorn a most full-range and believable depiction of trumpets and brass alike. 

This time, the SE84Cs were also able to vanquish the Loth-X BS1. With this dual mono configuration, they produced undaunted dynamics at very high volumes in my medium sized room, pushing the minimonitors to impressive, unprecedented sonorities. Because of the lower sensitivity of the Loth-X in contrast to the Klipschorn’s, the M3’s output had to be consistently set at near 11 o’clock. Rolling out waves of dynamics, the BS1 maintained tonal integrity during complex passages, as its focus on both the delicacies of strings and massiveness of brass did not waver. 

Playing the DSD-recorded horns of the London Symphony Orchestra from Les Troyens [LSO 0010 CD], the twin-SE84C coupled BS1 imparted the meticulously preserved upper midrange with a more fluidic substance, yielding considerable instrument definition while subduing the metallic bite slightly. Although operatic vocals garnered magnitude in volume and exerted drastic demands in scale from the BS1 over those of jazz, the monoblock set up harnessed the extra drive capability to accord the singers and orchestra with persistent ease and smoothness. The minimonitors were convincing testimonials to the Decware methodology as this set up induced refinement from the Loth-X when portraying the LSO DSD CD’s vocals, albeit a relative aggressiveness from a narrow band of the BS1’s upper midrange.

From the DMP jazz CD Further Adventures of Film & the BB’s [DMP CD-462], the Zen amps’ rendition of the brass carried efficacious luster and punctual dynamics. In “Jazz Patrol,” the trumpet/alto sax/tenor sax trio had differentiated dynamic contrasts while in concert with each other, thus imparting a more realistic sense of wielding of instrument. One memorable character of the Decware/Loth-X pairing was the soundstage spaciousness, which served to rid the BS1 of the confinement of its small cabinets momentarily. In light of my experience and preference in using the Genesis VI’s active servo subwoofers, although the BS1’s double bass conveyance remained limited, the pairing had enough subjective energy in the mid-bass region that it did not require addition of subwoofer for a fulfilling enjoyment. 

With the K-horn being a suitable match for the Zen amps, this fundamental characteristic improvement of the Loth-X as accorded by the Zen amps made listening to the minimonitors a most musically enchanting experience, ultimately securing for the Decware monoblocks/Loth-X BS1 my highest recommendation.

Next, to elevate the stakes a little, I hitched the Zen monoblocks to the $20,000 Audio Note AN-E SEC Silver loudspeaker. Although with SACDs, the AN revealed a surprisingly clear top-end to the Zen amps that was exceptionally revealing on instrument localization, an accompanying brittleness nevertheless persisted throughout. The manifest edginess plagued strings and brass from both SACD and Redbook CD alike, from heightened string graininess to overly bright brass, making for unnatural tonalities. 

When compared to my $3,400 EL34-based low-feedback Music Reference RM9 II power amp, for example, the AN-E SEC Silver pairing with the Zen monoblock configuration also revealed soundstaging more modest in scale and spaciousness, which led to a less credible sonic picture. In this regard, although DSD SACDs were capable of more resolute and more dimensional delineation than regular CDs, differences between the formats became less acute. Although the monoblocked output limitation could be the contributing factor to the soundstaging compromise, the Audio Note speaker’s resolution capability played an inadvertent central role undoubtedly, as this soundstaging phenomenon did not manifest itself through the Klipschorns.

The SE84Cs also produced dynamic distortions when pushing the AN-E SEC Silvers to very high volumes during climactic passages from both SACDs and Redbook CDs, a task at which the Decware/Klipschorn duo excelled. 

Coupling the Zen monoblocks to the 4-way, 4-speaker Genesis VI sans the subwoofers was another mismatch. In this case, despite the 90 dB/6 Ohm sensitivity of the Genesis, the mid-bass energy proliferation so resplendent with the Loth-X BS1 was curiously nonexistent, even from the Genesis’ otherwise benign specified 80Hz lower-end mid-bass coupler, and instances in which dynamic compression and collapse of soundstage occurred were bountiful.


The considerable superiority of using a pair of Decware SE84C amplifiers in a monoblock configuration over the use of a single unit in stereo was exemplified with the use of the $599 Loth-X BS1. The resultant punctual dynamics, spacious soundstaging and expressive tonalities secured for the Decware/Loth-X combo my top sub-$2000 amplifier/speaker recommendation. For readers with the extraordinarily efficient Klipschorns, I also recommend the mono pair of Zen amps, as the reasonable $1,000 investment may subdue for some listeners an edge of forwardness in the K-horns, while imparting encompassing frequency responses and undeterred dynamics.

Retrospectively, the $20,000 Audio Note AN-E SEC Silver permitted the most infinitesimal and unfavorable scrutiny of these very affordable Zen amps. While it would take consensual results from a listening panel to confirm or contest Decware’s claim of fidelity, I propose that the Zen monoblocks are best suited to driving small and efficient speakers, as such designs usually entail only one or two drivers with lesser bass and dynamic demands. As differing but noteworthy as Decware’s online customer testimonials may be discussing the successful pairing with a variety of speakers, it is conceivable that many audiophiles do not listen at the same volume I crave and therefore would not necessarily agree with my priorities.

Last and not least, when compared to Audio Note’s Quest 300B monoblocks and my recently acquired Reference Line Preeminence One Signature power amplifier, the SE84C monoblocks did not have the more predominant single-ended tonality, solid-state or vacuum tube. Therefore, dependent on your preferences, the Decware Zen amps can work for or against your goal.

Of equally paramount importance is attention to the proper matching of the SE84Cs’ output levels. Unless you are buying a matched pair of the SE84Cs for monoblocking from the start , it is crucial that you send your own unit back to Decware for calibration with the second SE84C. Furthermore, factory reconfiguration will eliminate the need for extra interconnects and speaker cables for strapping the amplifiers yourself. 

Steve Deckert’s concoction of hard-wiring his design and employing the Svetlana SV83 tubes is certainly a breath of morning air in the valve arena; but his choice of the $7 SV83 output tubes are undoubtedly the main factor to the Zen amps’ atypically mild tube induced overtones, despite the single-ended topology. 

I urge readers to take advantage of Decware’s 30-day trial offer for a first-hand account.

Decware Manufacturer’s Comments:

Dear Constantine,

I appreciate your continued interest in our entry-level Zen Triode amp for $499.00. Sounds to me like your discovery of the $599 Loth-X BS1 speakers will make it easy for audiophiles on a budget or with space limitations to enjoy killer sound! I should mention too that with no crossover on the Loth-X driver, the playback should be honest without artifacts like the accompanying brittleness you heard on the AN-E SEC.

But seriously, the problems you heard may not have been the speaker incompatibility at all, it could have been the preamp or source that has always been masked until the combination of Zen Triode and SEC speakers. I wonder if you had the same problem with the $2700.00 models? 

A selling feature of Zen Triode amps is that they are more neutral, less colored than typical SET amps.

“atypically mild tube induced overtones” are what exactly?

We understand reviews are a lot of work, and thank you for your sincere comments. We hope you and all of your readers have a wonderful holiday season!


Steve Deckert (309) 671 2428

Constantine Soo’s Response:

I would like to thank Mr. Steve Deckert for taking the time to send us his thoughtful comments. 

As a designer, Mr. Deckert’s opinions of the crossover-less Loth-X’s compatibility with his amplifier and the hypothetical inferiority of upstream equipment are noteworthy. I fully endorse a system consisting of the efficient, 2-way speakers Loth-X BS1 being driven by the Decware SE84C Monoblocks. Nonetheless, I also believe it will take an amplifier with more finesse than the SE84C to exploit the Audio Note AN-E SEC Silver fully. Watch for my upcoming reviews on Loth-X’s own $15,000 JI300 integrated amplifier and Linn’s $9,000 Klimax Twin power amplifier in driving the AN-E SEC Silver. 

Merry Christmas to our readers and Steve and DeVon Deckert!


Constantine Soo

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