Test of three-component Hercules MK II amplifier caused an agitated discussion in our site’s comments and in social media. Based on extensive customer input toward ‘producing something similar in terms of sound quality but less bulky and expensive’ Alexey Syomin designed a lightweight version of the combo, its schematic, workmanship and architecture being the same Hercules has.
MYTHS AND REALITY
The pace with which Mr. Syomin’s Sound Laboratory launches new devices is amazing. And these devices are not at all humble ones e.g. single-enders on a roll-formed chassis. The S.A.Lab’s production plant in Podolsk is equipped with modern machinery and measuring equipment. Equally important is the fact that the company itself designed the proprietary technology of transformer winding. And this transformer can be rightly called the heart of a tube amplifier. By the way, the winding unit design is closer to art due to multitude of conflicting factors whish can’t be calculated exactly and one has to exclusively rely upon experience and intuition. It’s no accident that transformers from Tango, Tamura, Partridge, UTC etc. hand-wound in the 20th century cost a lot nowadays. The transformers recently manufactured under famous brands aren’t highly ranked by the connoisseurs of tube sound for old masters’ secrets are believed to be lost and the materials aren’t what they used to be.
«The output stage of every mono block utilizes six 6П36С beam tetrodes (thoroughly matched and manufactures in the USSR in 1970s — three tubes in each pole) working in push-pull ultralinear mode».
Samson MkII mono blocks’ output transformers are the same Hercules has: they are hand-wound on a core made of the best Russian electric grade sheet and have size-to-power ratio of 1200 VА. The archtecture, which ensures wide frequency range and low losses, Alexey is going to patent.
The output stage of every mono block utilizes six 6П36С beam tetrodes (thoroughly matched and manufactures in the USSR in 1970s — three tubes in each pole) working in push-pull ultralinear mode. Such mode being something of an intermediary between working as pentode and as tetrode enables, among other things, to lower the dependency of THD on the load impedance. Besides, there’s no need to sacrifice a significant amount of output power. In our case six tetrodes provide 200W at any load impedance — thanks to the separate lines for connecting 8Ω or 4Ω speakers. The voltage amplifier utilizes 6072 tube (a double triode); driver is based on 12 W 6V6 pentodes (the substitute for the Russian 6П6С tube) working as triodes.
Power supply is not as substantial as Hercules’s but it also utilizes low slump Schottky diodes, chokes and substantial smoothing capacitors.
Generally speaking the idea of dividing an amp into three separate blocks is an extremely sound one. Thus we bypass limitations related to power supply; you don’t have to put components, namely transformers, too close to each other; pre amp can be placed father away from strong magnetic field generated by power amp. Surely it’s expensive to build three cabinets instead of one but for a High End device money is usually no object. The only problem — and from the audiophile point of view exactly — is a ‘redundant’ interconnect. Its impact is minimized by infinitesimally low (less than 20Ω) output impedance of the pre amp. Its last stage is based on a 9W 6П9С tetrode working as triode terminated on a transformer. Such a solution enabled to organize balanced linear interfaces with high load-carrying ability. There is a pair of RCA stereo outputs —fixed and variable one.
«Generally speaking the idea of dividing an amp into three separate blocks is an extremely sound one. Thus we bypass limitations related to power supply; you don’t have to put components, namely transformers, too close to each other…»
Pre amp ensures connection of three linear sources and three turntables with ММ cartridge. Phono amp is built on an ‘iron-clad’ 6J4 pentode and 6SN7 double triode with passive frequency-driving circuits. The necessary input can be chosen via remote; switching is conducted by small-signal relays.
The basis of Samsons’ monumental looks is the original design project. The faceplates are machined from Corian and decorative elements are genuine American walnut massif. The S.A.Lab logo and ‘Nothing but Music’ slogan backlit in sky-blue create stylish contrast to the artificial marble texture.
The Samson MK II threesome is delivered together with 4-story stand made from the same material as the components themselves. The combo costs $4500 weighing about 180 kilos.
To connect pre amp to power blocks Alexey offered cables of his own manufacture. Their main feature is that in order to avoid oxidizing the copper conductors are placed into an inert atmosphere: argon gas is pumped under the sheath. Working with Samsons these cables sounded very pleasant, but to make a final estimate it’s necessary to listen to them with other devices.
The current test started with vynil: Michell Engineering Orbe SE turntable with SME IV tonearm and Ortofon Cadenza Red cartridge via S.A.Lab step-up transformer connected to pre amp’s Phono input.
«No matter what schematic Phono amp utilizes the tube sound is immediately discernible. It ensures open stage with sweeping dynamics, clear upper end and mercurial non-ruse bass».
No matter what schematic Phono amp utilizes the tube sound is immediately discernible. It ensures open stage with sweeping dynamics, clear upper end and mercurial non-ruse bass. The subtler points’ sound may vary depending on the class of cartridge and other things, but as they say satisfaction is guaranteed. That’s exactly our case — although it seemed to me that Cadenza Red hadn’t made a perfect synergy with the step-up transformer (frankly speaking it was almost a chance encounter), listening to records was invariably a joyous experience. Smooth bass with slightly uplifted and therefore very expressive middle range, clear separation and enviable vigor… I can’t exclude the fact that with some tweaking a little more could be squeezed out of a vinyl record, but we had no time for that.
CDs made Samson’s features stand out much clearer. The continuity of generations was evident: Samson’s general approach to music was similar to that of Hercules (naturally one had to bear in mind the difference in speaker character). By the way I had some reservations about Wilson Audio speakers from the very start: to drive these Americans you need the amount of current that even an average solid state amp is not capable of producing. In our case what came to rescue was the proprietary S.A.Lab conception of switching output tubes with high load capacity in parallel and having huge surplus of joules in the power supply. There were absolutely no problems with dynamics, bass structure clarity and the amp’s ability to drive a big volume of space. 400 Watts is saying something: with this ‘strongman’ potential Samson’s sound doesn’t lose clarity or detail in quiet moments. By the fundamental difference between powerful tube amps and transistor amps working in Class AB is the fact that distortions at the first ten Watts are higher than at the second or the third ten Watts. The absence of deep negative feedback is also instrumental to truly opening the sound, freeing it and making it more natural.
«400 Watts is saying something: with this ‘strongman’ potential Samson’s sound doesn’t lose clarity or detail in quiet moments».
If we compare Samson Mk II to Hercules we must say that the junior “strongman’s” character is quieter, it doesn’t want to impress listeners with its explosive dynamics (although there are no problems in this respect) but is focused on the inner subtle aspects of music. Also it seemed to me that it has more expressive and harmonious middle range… On the other hand this experience may be attributed to the speakers.
All in all devices realized on such grand scale (unfortunately there are very few of them on the market) can change general public’s attitude to tube amplifiers. Having listened to such unit for at least half an hour even a rabid apologist of transistor technologies will stop believing in a myth that tube amps ‘don’t take a punch’, have problems controlling bass drivers and therefore work only with ‘lightweight’ speakers.
Michell Engineering Orbe SE turntable, SME IV tonearm, Ortofon Cadenza Red MC cartridge
Step-up МС transformer S.A.Lab
CD Player Lindemann 825
Wilson Audio Sasha II speakers
S.A.Lab Samson MKII
Manufacturer: S.A.Lab (Russia)
Output power: 200 W (4 Ω) || Signal/noise ratio: -110 dB (unweighed) || THD: 0,07 % (150 W, 4 Ω) || Size (mono block/pre amp): 460 х 190 х 470/460 х 270 х 480 mm || Weigh (mono block/pre amp): 35/60 kilos || Price with stand: $4500.
The editors thank the «Nota +» salon for their help in conducting the audition.