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atelier 13 audio


"Reinhard Thöress set out to exalt the treasures contained in the Triode tube, through a classic approach that has proven itself and a deliciously Retro look, a sound result unlike any other in its density, its presence, its energy and its realistic spatial presentation, serving all the emotion contained in each recording. Those who are connoisseurs of Valve-halla will be delighted by the Thöress amplifiers and their rare musicality"

A Tribute to Professional Audio Components from the Golden Age of the Vacuum Tube! 

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THOERESS F2a11 Integrated Amplifier TPT.png


Integrated Class A Tube Amplifier



F2a11 Single-Ended Triode Mode Integrated Amplifier

The F2a11 Integrated Amplifier utilizes the famous F2a11 vacuum tube in single-ended triode operation mode for an output power of 2x6 watts into a 4, 8 or 16 ohm load.


The F2a11 is a power pentode of matchless build quality. It was exclusively manufactured by SIEMENS in the 1950s and early 1960s which has been specifically designed for the most demanding industrial applications.


When operated in triode mode this extraordinary tube offers excellent sonics on par with the finest classic filamentary triodes such as 300B, 2A3, AD1 or PX25.


A 12SN7GT double-triode is employed in the driver stages. The triode sections of the 12SN7GT tube are equivalent to a 6J5GT single-triode, a highly regarded classic medium-gain octal base triode with fairly low transconductance from the early times of tube electronics, This tube is unarguably one of the most linear amplification devices ever developed in the history of electronic technology.


The F2a11 integrated amplifier can also be employed as a stereophonic power amplifier [ in combination with a line or full function preamplifier ], in which case the volume controls of the amplifier serve as input attenuators to match the gain of the line device to the efficiency of the loudspeaker.


Our All-Tube Integrated entirely relies on minimalist single-ended zero-feedback schematics..... Deliberately ignoring the fact that many music lovers persistently believe in the myth that balanced technology (and the associated cable configuration with XLR connectors) is generally superior to single-ended concepts. Readers who want to learn more about our view on balanced techniques and our general design approach and are encouraged to read the article (THÖRESS - Behind the Curtain) available on request.


The amplifier is built with meticulous hand construction using our proven point-to-point wiring techniques, whereby much care has been taken in arranging each aspect of the internal construction to ensure :

  • Low noise performance

  • Ease of service ...

  • ... and the highest reliability for many years to come.



The sound of our F2a11 amplifier is powerful, warm, clear and natural. When combined with high sensitivity loudspeakers, such as our highly efficient 2CD12 loudspeaker [96dB], the sonic presentation is of the utmost refinement, and will easily meet the expectations of even the most critical and experienced music lover.

Although reasonably priced, the F2a11 Integrated shares the non-compromise approach with our larger mono amplifier models. It is by no means an entry-level component, but a state-of-the art device which is likely to be sonically superior to any competitive product regardless of price.




The amplifier comprises 3 line level inputs (2x3 RCA jacks) with equal gain status selectable via rotary dial located on the rear panel.


High-grade continuously variable single-potentiometers are employed for separate (manual) volume control of the channels. These parts are made to our specifications by ALPS in Japan to allow for conveniently fine volume adjustment (taper with low angle sensitivity). Each pair of potentiometer is hand-picked from a larger production batch by careful measurement to ensure equal attenuation characteristics with respect to rotational angle (hence the slots surrounding the volume knobs are reliable scales for balance adjustment).


Notably, it is not possible to install remote volume control on the F2a11 Integrated. Music lovers who consider remote volume control as an indispensable feature are encouraged to take a closer look at our EHT Integrated Amplifier !





The F2a11 Integrated Amplifier is equipped with proprietary output transformers (OPT) of ultimate quality and that are made in-house. These parts allow for precise matching of a 4, 8 or 16 ohm loudspeaker load to the power tube by way of jumpers soldered to the secondary terminals.


Furthermore, the mains transformer is also produced in-house to the highest possible standards. Thus, we can easily build transformers for all kinds of mains voltages, for example for 100Vac (Japan), 120Vac (USA, Canada), 220Vac (South Korea, China, Thailand, Indonesia), 240Vac (UK) or 245 Vac (Australia).


Although the mains transformer has been optimized for low leakage and ultra low body noise emission it is mounted to the amplifier chassis via isolation elements in order to eliminate even the slightest interference of residual transformer vibrations with the circuit.

F E A T U R E  O V E R V I E W

  • All-Tube Integrated Amplifier utilizing the famous Siemens F2a11 Power Pentode in single-ended triode mode


  • The highly linear 12SN7GT double-triode is used in the driver stages

  • 2x6 watts of output power

  • Minimalist (pure class-A) zero-feedback schematic


  • High grade electrolytic capacitors (made in Germany) in the power supply​​​

  • 3 line level inputs (2x3 RCA jacks) selectable via rotary dial on the rear panel


  • High-grade continuously variable potentiometers for separate (manual) volume control of the channels

  • Ultimate tape wound cut core (C-core) output transformer with dual-coil winding manufactured in-house

  • Precise 4, 8 and 16 ohm loudspeaker load matching via jumpers soldered setting to the secondary terminals of output transformer


  • Ultra-Low noise low leakage mains transformer produced in-house for 230Vac (115Vac via jumper setting). 100Vac (Japan), 120Vac (USA, Canada), 220Vac (South Korea, China, Thailand, Indonesia), 240Vac (UK) or 245 Vac (Australia)

  • Full hand construction, point-to-point wiring throughout

  • Non-magnetic case (aluminum throughout

    • Anodized printing on front and rear panel

    • Powder-coated chassis and lids


  • Dimensions - mm : 

    • 150 W x 595 D x 330 H 

    • H / 330mm = 20mm (feet) + 210mm + 100mm (tubes over case)

    • D / 595mm = 575mm + 20mm (speaker binding posts)

    • Dimensions of the shipping crate - mm:

    • 950 D x 400 W x 460 H

    • Shipping weight : 18Kg each



Individually Made in Germany

MSRP   $ 10,000

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Show & User-System Coverage

Please Listen with Quality Headphones at Youtube Hi Res Settings

What the say ...


David Gryzb |  Sep 10, 2017  



A quick glimpse at the Thöress portfolio will surely make every SET amplifiers enthusiast to smile widely. There are eight products there now; two preamplifiers (one of which is actually a phonostage), two mono power amplifiers, two loudspeaker models, a pair of integrated amps and one of these – Thöress F2A11 – is this review’s hero. These items’ specs leave no room for guesswork. Large paper membranes, high efficiency, NOS tubes everywhere, ’70s alike (or even earlier) visual aesthetics are the Thöress way by no accident. To make such products for a living is a rare thing these days, a lot of passion has to be undoubtedly involved. One doesn’t do all this to become a millionaire, that’s for sure.


According to his subjective opinion, a truly world-class music reproduction system should be designed to be as universal as possible, namely every kind of musical program should be reproduced in equally appealing and convincing way. OK, usually statements of this sort are a marketing jabber and nothing more. Usually, which means that not always.


Reinhard’s F2A11 integrated is a very peculiar, unusual performer and in my opinion what he told me makes a perfect sense. Point being, after his deck’s audition with high efficiency speakers, suddenly everything about it became clear to yours truly, understandable and well thought. The moment of enlightenment and perfect awareness happened at some point and it’s scale would make Leonardo DaVinci blush, but to this topic we’ll come back later on.


I was also told that the Thöress operation doesn’t revolve around dogmatic tube designs. Reinhard uses the whole palette of ingredients and spices the universe of electronics offers him, of course in order to cook a meal as refined as possible. To translate this into properly technical lingo, he does everything in his power to provide the tubes with optimal operation conditions and then simply lets them to work at their best. Some things are off the menu, though. Reinhard says a big fat ‘no’ to integrated circuits and printed circuit boards, all of ’em are strictly forbidden with one exception – remote control purposes. There’s a number of valid reasons why so, yet this isn’t something Herr Thöress will share or discuss. In any case, point-to-point wiring is his credo in case of all products with the Thöress logo on them.


Thöress F2A11 is an integrated amplifier, which indicates that a preamplifier and a power amp are to be found inside the very same enclosure. Nothing new then, just add a pair of speakers, a CD player or a d/a converter and you’re good to go. Yet it’s more than important that this single-ended triode affair of ‘mere’ 6WPC is in constant sale and unchanged form for 15 years or so and the reason here is simple. To Reinhard, his F2A11 deck is a finished project, case closed.





NOS Siemens F2A11 beam power tetrodes work in single-ended triode mode in Reinhard’s integrated. These valves were used in the pro market and are very obscure. German Klangfilm cinemas exploited these in the post II World War era. Reinhard personally measures each of these NOS bulbs and I’ve been told that – once a good batch is bought – 70% of these is usable. But why tetrodes? Because they simply fit perfectly to a given task. Their low internal resistance (Ri) is comparable to 300B tubes. This parameter drastically affects transformer distortion D (indirectly proportional to Ri) and frequency response (the lower the Ri is, the more extensive the FR) of the power tube stage. In a nutshell, the lower the Ri is, the better. In addition, F2A11’s driving requirements are reduced by a factor of four in comparison to a 300B tube. Four times lower driver distorsion for the same power output than the latter is the outcome.


12SN7GT tube is one of the most linear medium-mu triodes ever made, a fact that is generally accepted and has been frequently proven by measurement. In the German integrated it’s operated at quite high idle current, in order to enable the most linear operation mode. For this purpose Reinhard employs a certain type of a custom made transistor which serves as the so-called active load for the driver triodes. Yet how our engineer does this part exactly remains his little secret.


The rectification stage is handled by ‘ultra-fast controlled avalanche glass body diode rectifiers’, or custom made transistors in short. Herr Thöress has found these non-boutique, easily available and inexpensive components to be the best for audio applications, particularly in terms of switching noise. Needless to say, he prefers them over vacuum tube rectification both objectively and subjectively. Since these components’ discovery, he never looked back at vacuum tube rectification. As he explained, he’s not into dogmatic tube designs and fitting glass everywhere just because.


Next in line are two tape wound C-core output transformers and one power transformer. All of these are handmade in-house by Reinhard himself – even his employees stay away – and mounted to the chassis via flexible dampers.


Electrolytic reservoir and filter capacitors and custom made for Thöress a ‘traditional’ German supplier Fisher & Tausche. This company actually delivers electrolytics for Reinhard.


In the F2A11 integrated there are no filter chokes but pure cascaded R-C-filtering instead. High tension supply stability is achieved via rather high capacitance values (over 1000 MFD) and low resistances in the filter cascade. Active regulation is off the menu as well.... and potentiometers are custom made by ALPS in Japan.



As far as valve based amplifiers go, there’s a certain stereotype. Soundwise these are often times said to be full of harmonics, hence warm and pleasant, at times slow, not really resolving, midrange oriented and focused on sheer pleasure delivery above all else. Some of them do sound in such way.


Though loaded with tetrodes set in DHT mode, Thöress F2A11 doesn’t fit this profile. Heck, it’s as far from fuzzy and syrupy aesthetics as possible. And the longer this German deck is on, the more impressive it becomes. Yet this time around the accommodation period is very short, the F2A11 integrated doesn’t need hours of work for one’s full attention. Reinhard’s machine gets the job done quickly, it sings fabulously right from the start and I’d lie by saying that it’s not impressive. It is and on many levels.


Let me elaborate. Thöress F2A11 is unusually transparent. It showed me in an instant what kind of a d/a converer was on and the same story was with the American speakers. Truth be told, I haven’t read anything about these before this assignment. I got myself familiarized with what the other Knight – Marek – wrote about said speakers in his material after the Thöress experience, and the two of us heard many similarities.


To me it was reassuring that, despite my fairly short time with the product by DeVore Fidelity, I was able to understand what it does. In any case, both loaners performed in a very synergistic way and there’s a number of reasons why. The F2A11’s PSU is quite overgrown, which translates to a nice control over given load and essentially increases agility. Orangutan O/93 sang in loud, clear and properly fit fashion with ‘mere’ 15% on it’s companions volume scale. Not even tiniest delay in the sound was heard, but firm grip over rather large membranes instead.


To explain this in proper audiophile lingo, low end extension was both present and authoritative, yet fabulously clear, texturally rich, differentiated and a spot-on stiffness was served as a cherry on top. Both excellent tension and leeway were present when needed, yet strictly track dependant. The American apes sketched very precisely differences between drums of different sizes on music by Kodo and Wardruna’s more tribal instruments. Point being, contrasts between these shown this clearly is something of great value. It was hard to shake off the feeling that the American-German duo was able to perfectly grasp very thin balance between downstairs’ swiftness and muscle tissue, everything simply checked out there, there was no desire for more. Yes, the characteristic bass-reflex rumble was mildly heard once in a while in certain spots within my own four walls. Yet these are the culprit here and neither this review’s hero nor speakers used.


Moving upwards, Thöress F2A11 turned out to be tonally even, hence it didn’t elevate any of audible FR parts. This product’s sound isn’t neither midrange focused, around which the whole rest revolves, neither with top or bottom elevated. It isn’t showy but perfectly clear, visible, clean and at the same time smooth and pleasantly saturated.


As far as its companions go, Reinhard’s deck will forgive a thing or two, yet to witness everything it does, well, there’s no place for cutting corners, especially as far as speakers go. Truthfully speaking, I strongly believe that I was able to know this deck to a certain extent only and am convinced that in a different company I’d be surprised what else it can do. My point is that the potential was obviously there. In any case, the confession above creates a profile of a product tonally not abnormal, transparent and both safely agile and thick. Thus far it sounds a bit like a class AB affair, hence nothing new and groundbreaking, doesn’t it? For now perhaps, but this story isn’t over just yet.


The fact that Thöress F2A11 has tubes on-board, yet doesn’t sound like a stereotypical product of this sort, is highly surprising. When asked whether this tuning was done on purpose, Reinhard confirmed. Well, there was a deep understanding between the two of us in this regard and – truth be told – a coincidence in this matter is highly unlikely...


Thöress F2A11 is very surprising on several levels. It’s selective, informational, doesn’t show music in prettier fashion than it already is and at the same time it remarkably shows any imperfections and differences in it. But all this is done in a very effortless, easygoing way. A listener hears a song poorly recorded, which oftentimes is the case with files, yet still served in enjoyable way, even though dense format of the same track is substantially better. My point here is that many analytical amplifiers known to me show weaknesses in music in a rather blunt way. The F2A11 integrated not only allows one to see this exactly, but also doesn’t strip the outcome from vividness and engagement. With this amp, even subpar tracks don’t sound artificial and dull and that’s not only interesting, but also leads to quite enjoyable outcome in such circumstances. Metallic tint on instruments of plainly bad “Thunderstruck” by AC/DC is there, yet so is live tissue. So in case of the F2A11 deck, where’s the downside then? The only subjective and far fetched weakness I could find is that this amp isn’t charming in the obviously tubey way. There are decks out there able to paint even richer, more colorful picture. And to some individuals on a lookout for a typical product with tubes on-board, our German machine simply might not be it as it will play nicely with lifeless speakers only to some limited extent. Reinhard isn’t about regularities, that’s obvious, hence either one likes his unusual approach and sound or he’d be better off somewhere else.


What’s on the menu thus far is interestingly sounding ... and great product. But where’s the magic? Well, imaging is the place to look for it. I could simply say that Thöress F2A11 gets the job done in terms of width, depth and height of the soundstage, that everything is of reasonable proportions and so on. I could also state where to look for the sound, be it between the speakers or all across the room. But everything checks out here, the soundstage itself is well developed and there’s not a single reason to be displeased as long as speakers/monitors used do keep up ...


But what’s different is how organic the whole image is. It can be felt that it’s a very vivd, moving being with precisely sketched, embodied and properly thick organs, which are marvelously separated one from another. The sensation is somewhat comparable to looking at not solid but translucent mannequin with all of its vital parts perfectly visible. Yet not mass produced in a big factory owned by one of industry’s giants but crafted in a small boutique workshop by hands of a virtuoso doll maker. This makes the difference indeed ...


The space between instruments is alive as well, and the issue of environment recognition is non-existent, of course as long as this information is audible on a given track, which is a completely different story ...


My point is that Thöress F2A11 shows background like a true champ. My Trilogy 925 integrated does something similar as well, yet is the thicker and darker performer, hence a bit different here. Now in case of the F2A11 model, let’s add generous amount of air between all elements ‘visible’, openness and agility  ... and thus, the outcome can be only one : effortless, stress-free, mildly euphonic and engaging sound, crafted by someone who not only feels the subject but also knows how to pull this off. 


Reinhard’s product is euphonic, valve charm is surely there, yet at the same time is also very natural and balanced. Its virtues, "alltogether", are on the pedestal, and this is not a situation where one individual feature is much more pronounced than the rest ... This isn’t the case at all  ... So,"chapeau bas" [hats off] to Reinhard for making a product without obvious weak spots. 


Past the usual several days long routine, the only thing left to do was to involve the more affordable FirstWatt F7 power amplifier, driven by my reference d/a converter directly. Paradoxically this Class A transistor affair by Nelson Pass sounds warmer and is less agile than German integrated, which might be quite the shocker to many individuals, yet both machines get the job done in a manner way too obvious to not hear it. Not a subtle difference here and there, oh no.


The only common denominator is great control over connected load, as each deck did fabulouslt well here with the American speakers. The impact in the lowest audible octave, and slightly above, in both cases was firm, massive and even somewhat physically sensible where it should. Yet Thöress F2A11 turned out to be more agile in general, with slightly edgier bass contour, whereas the F7 amp was the softer, rounder, heavier, more spherical and less emergent one in this regard. Such tendency was also audible upstairs.


The product by maestro Pass not only sounded thicker and warmer, but also calmer and – to put this in more colloquiall words – more laid back. The sensation of musical presence was slightly weaker in comparison to the F2A11 integrated as the German deck is more about the ‘here and now’. F7’s top extension decayed quite similarly, yet was of lesser presence, hence this machine turned out to be gutsier and darker. It also focused one’s attention on events between speakers, wasn’t as airy and it involved a listener in a different, more romantic, seductive way. Reinhard’s F2A11 product showed bigger sound sources and usually served them a bit closer. At times vocal parts were very intimate in effect, which led to well known recordings shown from quite different perspective and favourite music rediscovery in one full track at a time fashion was the outcome. At least that was the case with me. I can’t recall when Blixa Bargeld was more present and convincing on “Sabrina” by Einsturzende Neubauten, the same story went with female vocalist on “Zefiro Torna” by Michael Goddard’s ‘A Trace of Grace’ album and another examples I could multiply. Having both FirstWatt F7 and Thöress F2A11 under one roof was comparable to possession of two luxurious and exotic cars, yet completely different and driven accordingly to their owner’s mood..



After several weeks spent with Thöress F2A11, it turned out that this integrated is as good as it is unique. Yes, very. Tube amps are rather rare guests in my audio cave and several weeks back, the company established by Reinhard Thöress was off my radar, hence initial expectations were quite non-existent. Yet practice forced me to catch up, simply because the longer this machine was on, the more obvious it became how great it is. The outcome is that if high efficiency speakers will ever become a permanent part of my setup, Thöress F2A11 sooner or later will find its place somewhere nearby as well. In such circumstances it won’t be a matter of ‘if’ but ‘when’ instead.


Thöress F2A11 is visually peculiar to say the least, to some people controversial even, yet finely crafted nonetheless. Each of its elements indicate that someone took his time. Volume knobs, input selector or heat dissipation… everything checks out as if this machine was made for personal pleasure and use. Heck, even small details (i.e. lacquer coating inside finely assembled enclosure, hence normally unseen) sport this attitude and at the same time show clearly Reinhard Thöress’s mindset. He’s a perfectionist as far from trends and competitors’ doing as it gets. And now, after the F2A11 experience, I confess that this deck’s visuals grew on me to a point of being very appealing, even though the very first impression was vastly different. Go figure ...

It’s appropriate to say that the so-called German engineering is seen in Thöress F2A11, yet it’s the sound that makes everything about this deck simply click. Rest assured that in case of this very unique and stereotypes overthrowing performer, the so-called vacuum goodnes is a part of the show, and so is insight into recordings and associated electronics ...


But that’s the overly simplified statement, merely a fracture of much grander scheme. Transparency, effortless and open image, vividness, euphony and intimacy on demand are properly descriptive measures and that’s not it yet, still.


How Thöress F2A11 gets the job done in terms of individual instruments, how it shapes and places these in virtual space, what picture it paints in general, well, these are the case and lead to a truly magnificent outcome, difficult to fully dress in words. The overall experience is magical in a way, and to witness it is to understand. Again, this scribe is not language savvy enough to grasp the whole F2A11 sensation in more understandable and informative way. 


Let me simply say that the German machine sounds like it’s enchanted and is highly addictive in effect. Shortly past my loaner’s return is when I understood fully how special deck just left my place. The Thöress experience still sits in the back of my head and I strongly believe that it’s not going anywhere anytime soon.


To describe a soulless audio product as one with spiritual inside is neither informative nor appropriate. Usually to serve such expression is to emphasize one’s highly emotional and a bit exaggerated attitude towards… a machine. To be frank, a statement of this sort is both of zero informational value and redundant. And yet in case of marvelously built, fabulously sounding and visually unique Thöress F2A11, I’ll gladly make an exception as I strongly believe that it’s the right thing to do this time around ... 


This complete, unique and spectacular integrated is highly recommended to every high efficiency speakers aficionado out there. Not only as a product for years to come, but also a very rare case with soul indeed. Till next time !


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