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Reviewer: Srajan Ebaen
Financial Interests: click here
Source: APL NWO 3.0-GO; Ancient Audio Lektor Prime; Raysonic CD-168
Preamp/Integrated: Supratek Cabernet Dual; ModWright LS-36.5/PS 36.5; Wyetech Labs Jade; Almarro A318B; Melody I2A3; APL UA-S1; Woo Audio Model 5; Raysonic SE-20MkII [on review]; Trafomatic Experience One [on loan]

Amp: 2 x Audiosector Patek SE; 2 x First Watt F4; Yamamoto A-08s; Yamamoto A-09s; Fi 2A3 monos
Speakers: Zu Audio Definition Pro; DeVore Fidelity Nines; WLM Grand Viola Monitor with Duo 12; Rethm Saadhana; Zu Presence [on review]; Mark & Daniel Maximus & Ruby Monitors w. OmniHarmonizer

Cables: Ocellia Silver Signature loom; Crystal Cable Ultra loom; Zanden Audio proprietary I²S cable; Crystal Cable Reference power cords; double cryo'd Acrolink with Furutech UK plug between wall and transformer; Stealth Audio Indra and Meta Carbon
Stands: 2 x Grand Prix Audio Monaco Modular 4-tier
Powerline conditioning: 2 x Walker Audio Velocitor S fed from custom AudioSector 1.5KV Plitron step-down transformer with balanced power output option; Furutech RTP-6 on 240V line feed
Sundry accessories: GPA Formula Carbon/Kevlar shelf for transport; GPA Apex footers underneath stand, DAC and amp; Walker Audio Vivid CD cleaner; Walker Audio Reference HDLs; Furutech RD-2 CD demagnetizer; Nanotech Nespa Pro; Acoustic System Resonators and front wall sugar cube matrix
Room size: 16' w x 21' d x 9' h in short-wall setup, with openly adjoining 15' x 35' living room

Review Component Retail: C-03 $9,500; A-100 $19,000

A 20th anniversary is high grounds for celebration, be it marriage or business. And Esoteric's engineers have turned over tables and pages to make theirs a splash. On the digital side -- what the company is still best known for -- they gave us this year the P/D-05 separates. Enter the two-years-in-development VMK 5 sled. And say hello to the 32-bit AKM converter. On the analog side, we have two firsts for Esoteric - the C-03 solid-state preamplifier and the A-100 all-tube convertible amplifier. The latter is convertible because it can operate as a remote-controlled four-input integrated or a standalone stereo amp (which then bypasses all redundant volume and input switching circuitry).

While the thermionic output devices might be surprising for this firm -- 4 x KT88 UL push/pull for 45wpc -- surprises don't end there. The three-stage circuit employs direct-coupling, active servo bias and custom output transformers whose 2nd-order coils are fabricated from a silver-plated copper foil. Performance specs read ambitious, too: Frequency response of 20Hz to 60kHz +1/-3dB (albeit given at 1 watt/8 ohms, not full power) and a colossal S/N ratio of better than 98dB. For the direct input, the input impedance is 1M; for the line inputs 10K.

Mass of 40kg/ 88lbs once again confirms Esoteric's vault-type enclosure standards with dimensions of 382 x 252 x 486mm (15 1/16 x 9 7/8 x 19 1/16 inches). Power draw is 200 watts. A 4 x 12AU7 cathode follower and driver stage connects the 2 x 12AT7 voltage amplification stage to the tetrode power buffer. Auto-adaptive active bias constantly monitors power stage bias, output voltage and cathode current. A patent-pending zero voltage control circuit stabilizes the cathode follower's DC output levels for the direct-coupled circuit components under real-time comparisons between driver and output stages.

A rear-panel mode switch selects between bias A and B. B is considered the default setting, A applies slightly reduced bias voltage. The copper/silver transformer secondary is said to provide unusually tight coupling to the primary. All small-signal tubes are DC-heated for superior noise performance. Unlike the output tubes, they are driven by fully stabilized power supplies. Those and the output transformers are wedged inside a rigid 'H' assembly which is surrounded by circuit component blocks inside the outer main frame. The RCA inputs are WBT-0201, the speaker terminals WBT-0710Cu. An illuminated remote for integrated amplifier operation is standard.

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Deservant of special mention is the obvious. Traditional tube amps even from big Japanese companies like Luxman always display the valves on deck followed by either exposed transformer canisters or a solid cover for all the iron. To engineer the circuitry with it transformer, choke and valve bits such that, puzzle-like, everything fits together inside an apparently monolithic structure while keeping the signal path the shortest possible, stray fields shielded and the tubes accessible for eventual replacement... well, let's just say this compaction appears to be far from easy and is hardly ever done. But, it beautifully transcend the otherwise obligatory tube cage which never looks completely integrated aesthetically. Esoteric's solution reminds me of the Mercedes Gullwing except that the bent tube panels here aren't hinged on top to fold up.

While on compaction and puzzle, if you've kept count, you surely must wonder by now where Esoteric has hidden away the six small signal tubes mentioned earlier for the voltage gain and cathode follower stages. And you might also wonder about further details on their patent-pending auto-adaptive bias solution.

The small signal tubes are exactly where they should be - lined up ahead of the output tubes to
which they couple without capacitors. Simply remove two bolts each to lift up the covers from the standoffs.

The unusual knob in the center of the rear panel is nothing more than the motor housing for the potentiometer. Esoteric advised to not try removing it.

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At HighEnd 2008 in Munich, I caught up with Esoteric president Motoaki Ohmachi (right) and Kazutaka Tsuda, department manager of overseas sales (left). While Ohmachi-San oversees a team of engineers, it's his input which guides them. His ears determine which paths are followed and every single A100 is personally listened to by him before getting sealed in its box for dispatch to its final destination.

As his remastered Esoteric CD of Beethoven's Overtures shows [Sir Colin Davis, Bavarian Broadcast Symphony Orchestra, The Ruins of Athens Op. 113, Coriolan Op. 62, Leonore No.1 Op. 138; The Creatures of Prometheus, Op. 43, Egmont Op. 84, Leonore No. 3 Op. 72A, Fidelio Op. 72B], Ohmachi-San's reference is the symphonic orchestra. Fully cognizant of power tube virtues, for the A100 he was intolerant of their weaknesses. "More bass, higher treble" were the stern demands. The patent-pending bias circuit, unique ribbon output transformer and capacitor-less direct-coupling are direct results of this engineering brief. What he listened to during R&D and using this particular CD among others -- I was gifted with a copy for the review -- were soundstage width and depth, layering, image specificity, instrumental timbres, dynamic scaling and the sound of massed strings.

To demonstrate raw drive before any showgoer might question it, Esoteric demonstrated the new amplifier in Munich with the above Dynaudios in a sizeable space. And while the amp can be run direct, best performance demands Esoteric's new C-03 preamplifier which deliberately eschews valves for the very best S/N performance and resolution.
I'd use my Supratek Cabernet Dual and ModWright LS/PS36.5 preamps but, Tsuda-San had slyly confirmed my interest in teaming the A100 with the C-03 and that's indeed what Japan dispatched to Cyprus for review - their premier pre/power combo.