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AUDIOMAGAZINE: S.A.LAB ERATO MK.2 PRE/POWER AMP

Prise: 4 500 000 ₽ (per set)

Reviewer: Arthur Frounjan

January 21, 2015

ASCENT OF TUBE EVEREST

 

In the realm of high-end compromise is virtually a profane word. Both high THD and irregular frequency response have long ceased to be perceived as absolute or even relative evil. Nothing causes such persistent rejection as compromises although their various guises overwhelm not only audio but our life also. Still what happens if you design at least a single no-compromise audio component? Is it even possible? The question would be left unanswered had it not been for a few desperadoes that are sparse in our world. One of them is Alexey Syomin, a Russian engineer, author of no-compromise audio components at least in comparison with the vast majority of mass-produced devices. He manufactures them by hand under his brand of S.A.Lab (Sound Analysis Laboratory).

He went a different way…

 

Where do audio compromises begin? They surely start with economic factors followed by the practical ones: size, weight, ease of use, design and even power consumption. When engineers aim to create some outstanding device their fervor is inevitably cooled off by accountants, technologists, designers, market specialists and others propelled by voice of reason. Each one of them tries to force the ambitious project into Procrustean bed of their beliefs. Been born in pain it is ruthlessly depraved of its audacity and shamelessly called no-compromise. Alas, an uncompromising approach is incompatible to commercial considerations.

 

The case of Mr. Syomin is unique in his notion that high-end is not business but more of an… anti-business, a hobby, an oddity. Fortunately he already owns a business but an entirely different one connected to economic management. That’s exactly how he provides for his expensive absolutist hobby. He had to pay about 80 000 rubles (about $2500) just for the British M4 steel to make a core for output transformer. And that is not to mention the winding costs…

Alexey Syomin has been designing amps since he was a six-grader. First he worked with tubes then moved to transistors when they become available. Having decided to attempt the absolute he chose euphonic sounding tubes. (Strictly speaking transistors can be as good too.) But a question arose: tubes are numerous so which one to choose? It was dull to repeat what others’ successful achievements. Much more tempting was to conquer the top of all tops. But this was also deceptive: it was hard to surprise anyone least of all oneself with win-win 300Bs and 2A3s. Moreover even capricious ГМ-70s, 845s and 211s were rather common in audio. He wanted to plough virgin land — to create an amp powerful enough to drive not only highly sensitive horn-loaded speakers but any speakers! We’re talking at least 50 Watts of output power.

 

Having selected 14D13 tube, a powerful filamentary triode of British pedigree, Mr. Syomin used it for constructing single-ended mono blocks producing 45 Watts of honest output power. Preliminary stage was placed into a separate enclose as bulky and heavy as the amps themselves. This model that saw the light of day in summer of 2012 was called Ligeia.

Six months later similarly constructed amp was presented. Even its output transformers turned out so bulky they had to be placed into separate enclosures too. Rare British tubes gave way to Russian ГУ-80, a filamentary generator pentode. This two-horned monster with red-hot graphite anode consumes more than 10 A in its filament circuit only! In the previous issue of our magazine we discussed the original Erato; now we’re investigating Erato Mk.2.

 

Strictly speaking the virgin land mentioned above had already been touched by a plough. Time and again ГУ-80 had been used for amplification both in Russia and in the West. For instance the late Mr. Yuriev, a well-known designer of tube audio, utilized it in his Storm mono blocks. But his tube worked in its natural mode as pentode while Alexey turned it into a triode. It’s not difficult: you only have to connect the second grid to anode via a resistor that limits the grid current and therefore the power generated on it (otherwise the tube would burn out). In this move the tube manifests electric qualities suitable for audio designer if he ignores its huge power consumption. Instead of 2000V it’s sufficient to deliver 900V to anode while inner resistivity lowers from several kΩ to 500 Ω. Therefore output transformer becomes less complicated i.e. higher quality.

According to Mr. Syomin’s opinion this tube working as triode not only produces exclusive linearity of response as, by the way, all filamentary triodes do, but soundwise gets very close to the legendary 300B. The latter tube is every audiophile’s favorite. Some curse it but only after taking their hats off. On the other hand it can’t produce more than eight or nine honest Watts. And here we get as much as 100W without any tampering with grid current!

 

It’s only natural that no-compromise components featuring this huge tube turned enormous: two power mono amps and a pre amp the size of floorstanding speakers plus a pair of output transformers. All of them are enclosed in boxes manufactured from ash wood massif. If it weren’t for the tubes it would be easy to mistake the enclosures for pieces of antique furniture. The amps are filled with heavy iron to such extent that less solid carcasses would implode under their own weight. And if they were metal or stone it would take a small forklift to move them.

 

But isn’t there a contradiction somewhere? The real high-end audio favors short signal paths and only tubes give designer an opportunity to limit amp schematic to only two or three stages of amplification. But Mr. Syomin thinks it’s better to add one more stage than to make tubes work at the limit of their capabilities. And we mustn’t forget that the service electronics quality is to be high enough to provide for high voltages and currents. For instance the amp has a five-stage procedure of turning itself on: first half of heating voltage is provided, then full voltage, then a third of anode voltage, then half of it, then anode is fed with full voltage. Input and preliminary stage stabilizers also feature tubes and power transformers therefore they are bulky too; not to mention the output stage power supply with huge transformer and choke; besides there is a separate power supply for heating output tube cathode. The supply utilizes a substantial choke and a bank of capacitors of 100,000 µF total otherwise the smallest voltage pulsations on anode or filamentary cathode would modulate signal and cause audible noise. That’s why Mr Syomin’s devices are so heavy.

 

Some readers may be surprised by the absence of kenotrons integral to the orthodox tube amp. This is caused not by the desire to reduce the amp’s size, but by the necessity to replace kenotrons almost every month due to ГУ-80’s high anode current (0.5A). Gas-filled tube rectifier as non-vacuum alternative is also unsuitable due to excessive level of inherent high-frequency noises. That’s why amp’s rectifier features high-voltage silicon carbide Schottky diodes with negligible p-n junction capacitance and virtually non-existent reverse-current impulses due to finite carrier storage time in the junction.

Driving the output tube isn’t easy at all for it requires high signal voltage. This voltage is provided by 300V driver stage connected to the tube by a transformer. Input stage features classic VT25 triode (RCA) linked to the driver via a capacitor manufactured by Danish company Deulund using silver foil and paper dielectric. This component was chosen with special care for unlike a transformer that can be calculated according to designer wishes and wound on required core we have to use a ready-made capacitor. Deulund caps are fabulously expensive (approx. € 800 per item!) but their sound exceeds even the best ‘paper-in-oil’ Jensen capacitors. So how can you get by without them?!

 

Is there any other audio device anywhere in the world featuring such expensive parts? Economics rigidly restricts their usage to individual upgrades or unique DIY designs. But no chance of mass-production otherwise the company accountant will hang himself!

 

Now I have to explain some matters concerning wound components that are plentiful in this amp. It turned out virtually impossible to wind a transformer in Russia to requires spec for technologists inevitably made their adjustments thinking they knew the winding process better than anyone. So Alexey had to order abroad, in Ukraine or Italy. They never asked any questions and made everything exactly to customer’s specs. But it amounted to substantial extra expense!

Let’s talk pre amp now. It features two stages with galvanic coupling and transformer output. Its output impedance is just about 7Ω. Input tube is WE310 pentode while output is a filamentary 45 tube. Pre amp features four line inputs and 24-step volume control based on modified DACT of Danish manufacture with SMD metal-film resistors exchanged for better sounding tantalum. Apart from input switch and volume control there is one more turning knob for muting.

 

Similar to mono blocks (with the exception of their output stages) carefully filtered and stabilized feeding voltages are fed to each pre amp stage from a separate transformer. Compensating stabilizers are regulated by 6AS7s (analogues of Russian 6Н13С tubes) and controlled by iron-clad 6ж4 pentodes. Reference supply sources are voltage regulator tubes. Both acoustic and interconnect cables are of S.A.Lab manufacture. They have original geometry with copper and silver strands for acoustic cables and only silver strands for interconnects. All cables have organic silicon isolation used for military space industry. According to Mr. Syomin such isolation betters even Teflon foam.

Listening to a tube dinosaur

 

It would be improper to connect these strongmen to speakers of reasonable volume although you don’t have to bear in mind the compatibility based on sheer size. High-end is neither boxing not wrestling for it has no weight categories. There are price ranges instead. Nota+ salon management rolled out (literally — on wheels) enormous Wilson Audio MAXX3 speakers. Having obviously left their cartons only recently they hadn’t yet rolled up to their optimal placement. Audio stage had scale and spaciousness but there were some lower register problems. On order to catch the bass (the pun is entirely unintentional) you had to move your armchair incessantly. The bass was there but it tended to sneak away like a dog into his kennel. Unfortunately a top high end experience can be easily spoiled by mediocrity of presentation. But what makes a proper expert? An ability to make adjustments for external environment and extrapolate his experiences in order to come to a sufficiently credible conclusion.

What is the major sound feature of a single-ended amp featuring powerful filamentary triodes? It is the colorful velvety middle coupled with sparkling superbly detailed highs. The most successful installation also boast warm breathe accompanying each percussion sound and apparently stretching down on the frequency scale almost to the upper bass range.

Listening to a tube dinosaur

 

It would be improper to connect these strongmen to speakers of reasonable volume although you don’t have to bear in mind the compatibility based on sheer size. High-end is neither boxing not wrestling for it has no weight categories. There are price ranges instead. Nota+ salon management rolled out (literally — on wheels) enormous Wilson Audio MAXX3 speakers. Having obviously left their cartons only recently they hadn’t yet rolled up to their optimal placement. Audio stage had scale and spaciousness but there were some lower register problems. On order to catch the bass (the pun is entirely unintentional) you had to move your armchair incessantly. The bass was there but it tended to sneak away like a dog into his kennel. Unfortunately a top high end experience can be easily spoiled by mediocrity of presentation. But what makes a proper expert? An ability to make adjustments for external environment and extrapolate his experiences in order to come to a sufficiently credible conclusion.

 

What is the major sound feature of a single-ended amp featuring powerful filamentary triodes? It is the colorful velvety middle coupled with sparkling superbly detailed highs. The most successful installation also boast warm breathe accompanying each percussion sound and apparently stretching down on the frequency scale almost to the upper bass range.

 

Listening to this system I experienced all of these. Nevertheless my experiences came not so much as surprises but as statements of fact. To turn buds into flowers you just have to spent a couple of days choosing the right cables, finding the proper speaker placement or simply burning the system in.

 

The sound didn’t cause any annoyance or mistrust on subconscious level. Moreover you could feel the sound pedigree that was difficult to hide despite the system was not in its best mood. Apart from that I had a rare feeling of unique warmth and seductive friendliness.

 

By the way, the higher quality a high-end system has the more capricious it becomes. Like a living being it one day may radiate energy and joy of life and the next day having got up on the wrong foot won’t make the listener happy whatsoever.

I can’t help mentioning that the original Erato (we’re testing the second slightly upgraded — and the last — sample) while being demonstrated at MHES autumn show sucked people into its room like a vacuum cleaner and despite the show specifics used to bring them on the verge of awe-inspired numbness. The ‘new’ Erato sounded very much like the original but lacked a proverbial pinch of salt to turn the sound foie gras into a proper tour de force.

 

Comparing the same CD and SACD tracks for player could read both formats I encountered some discernible but critical differences. On SACDs musical instruments had more complex and intuitively credible relief. Their spacing was more exact while casting deeper acoustic shadows of uncut overhang. Nevertheless there were some pleasant surprises e. g. Ahmad Jamal’s powerful piano accompanied by spacious Chicago Symphony Orchestra sounded breathtakingly beautiful.

Pre/power Amplifier

S.A.Lab Erato Mk.2 (4 500 000 rubles per set)

 

TECHNICAL SPECS [ AS PUBLISHED BY MANUFACTURER ]

 

Output power 100W (4 / 8Ω)

Frequency response 10Hz-45kHz (–1dB)

THD 0.01% (1kHz, 1-50W)

Inputs  4 (2xRCA)

Outputs  2 (2xRCA)

Consumption 1300W

Weight >700kg

 

THE MUSIC

 

DISC 1 Billy Joel. «The Stranger» (CD, CBS / Columbia CK 34987)

DISC 2 Billy Joel. «The Stranger» (SACD, Columbia CS 69384)

DISC 3 Miles Davis. «Kind Of Blue» (CD, Columbia 88697 27105 D-1)

DISC 4 Miles Davis. «Kind Of Blue» (SACD, Columbia CS 64935)

DISC 5 Ahmad Jamal. «Blue Moon» (CD, ACM — Jazzbook Records JV 57001)

DISC 6 Dee Dee Bridgewater. «This Is New» (Verve / DDB Production 440 016 884-2)

DISC 7 Patricia Barber. «A Fortnight In France» (Blue Note 7243 5 782 / 3 2 2)

DISC 8 Mussorgsky. «Pictures At An Exhibition» / Chicago Simphony Orchestra / Neeme Jarvi

(Chandos CHAN 8849)

DISC 9 Bach. «Sonatas & Partitas for Solo Violin / Henryk Szeryng» (Deutsche Grammophon 437

366-2)

DISC 10 Puccini. «La Boheme Opera Collection» / Orchestre National de France, James Conlon /

B. Hendrix / J. Carreras (Erato / Teldec / Warner Classics International 0630-13813-9)

 

TEST TRACT

 

ProAc Carbon Pro Eight, Wilson Audio Sophia Series 3 speakers

McIntosh MCD500 СD/SACD Player

S.A.Lab interconnect cable

S.A.Lab acoustic cables

XLO power cables

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