Thöress Dual Function Preamplifier 845 Mono Amplifier

Thöress - A Tribute to Professional Equipment from the Golden Age of Electronic Tubes

Among the audio equipment we awarded during Audio Show 2012 with the Best Sound there was a small, unusually looking phonostage from the German company Thöress. I met its owner, Mr. Reinhard Thöress, in May of the same year at the High End 2012, probably the first one—as long as my memory serves—that he ever participated as manufacturer. I mentioned the looks of this device, because before you even start listening to it you will have to undergo an accelerated adjustment course. But only if you were born after, say 1980.

If you are about 40 or more years old, there is a good chance that you may have come across maybe in a school workshop, or some other workroom, some industrial measuring equipment, amplifiers, heaters, etc., which looked exactly like the audio system under review. It looks like the quintessential industrial design of the 1950s and 60s, with Dual Preamplifier's distinctive knobs, and with exceptionally good-looking cooling slots in the 845 Monoblocks. And then there is this lacquer of a very interesting, unusual shade. Both devices under review were presented for the first time at the High End Show 2017 in Munich. Both are also the top-of-the-line products of this brand.

It is one of those companies whose creations one immediately falls in love with or hates them. These are the only two options. Both attitudes are equally understandable. For me, because I had encountered similarly looking devices in the past, this aesthetics was close and understandable because of its functionality and ideological transparency. Actually, it was more than understandable! The control unit for the ceramic oven, which I made with my classmate in the fifth grade of the technical school belonged (aesthetically) to the same "family" of products. So for me this was something fascinating and personal.

The widely used name of the company is Mr. Reinhard Thöress' surname. The full name is actually: Thöress Puristic Audio Apparatus. While most people are usually impressed by his amplifiers, Mr. Reinhard points out that, in fact, ever since the company was founded 20 years ago, he's been building amplifiers AND high efficiency loudspeakers called 2CD12 (97dB, 61,490 PLN) and 1D8 (90dB , 36,990 PLN). He does not stop there and says, "The acoustics of the room and the audio furniture are the basic elements of an audio system, not just accessories!" The company is based in Aachen, near the border with Belgium and the Netherlands.

Dual Function Preamplifier

Same as the looks—utilitarian and functional—the nomenclature is equally clear. The dual function of this device is the function of a line preamplifier and a headphone amplifier. And it's not a "line preamplifier with a dedicated headphone amplifier," which could suggest to the first function as the more important one, nor a "headphone amplifier, which can also work as a line preamplifier," which in turn speaks of the headphone's superiority. It's one device, but with two equal functions.

This is a tube preamp / headphone amplifier with semiconductor, stabilized power supply. The electronic circuit is based on NOS tubes, two per channel, operating as triodes in a class A without feedback. It features six pairs of stereo inputs and three pairs of outputs. The front panel features four illuminated knobs, with a large circle around them. I do not know if you have noticed this, but this is common to Thöress and Ayon Audio preamps, especially to Spheris III.

In addition to volume control, input selector and on/off switch, there is also a knob for softly adjustable tone control and an attenuator to set input's sensitivity. It is mainly used when using headphones. These can be connected to one of the two large jack outputs—a small toggle switch allows user to choose between them. In the middle position both outputs are inactive. Regardless of how the switch is set, the line outputs are active. The device has a very low output impedance and can be used with headphones with an impedance of up to 30 Ω without an output transformer. The whole circuit is hand-made using point-to-point technique.

The preamplifier is equipped with an infrared receiver that controls the motor, which turns the volume knob.

845 MONO

The 845 Mono power amplifier features a deep chassis with a narrow front wall. This is a tube amplifier, with a semiconductor power supply. It is built around Directly Heated 845 power triode in SET circuit without feedback. Amplifiers were delivered for test featuring KR Audio. power tubes. The tubes are paired so that both monoblocks' measurements match almost perfectly.

As drivers for the 845s Reinhard chose two, exceptionally powerful, EL803S pentodes that work here in triode mode. These are NOS tubes, working in parallel—the company's materials speak of a "single control stage consisting of two tubes". It is so powerful that, in theory, it could drive speakers directly. All three are mounted from the top, giving the same visual effect as once in the Nagra VPA amplifiers.

The amplifier outputs 20 W (data from the website, it says 25 W in the manual). There is a single pair of speaker terminals on the rear panel, but one can configure units for 4, 8, or even 16 ohms, just by re-soldering jumpers on the output transformers. Yes, the transformers—you should know that all of them, also chokes, are made in-house by Thöress. The circuit utilizes high quality components such as: Vishay capacitors and resistors, oil capacitors, etc. The system is hand-made in point-to-point technology.

Test Methodology

The reviewed amplification replaced my Ayon Audio Spheris III preamplifier and Soulution 710 solid-state amplifier in my reference system. The source was the Ancient Audio AIR V-edition CD Player, but I could not deny myself a pleasure and listened also to the Marantz SD6020R tape deck. It was beautifully restored by the Nomos company, which—by the way—will soon open a showroom in Krakow devoted exclusively to vintage equipment! The amplifiers drove my Harbeth M40.1 loudspeakers that are not easy to drive.

I performed a separate listening session using headphone amplifier driving HiFiMAN HE-1000 v2, Sennheiser HD600 and the 20 years old Beyerdynamic DT-990 Pro.

The manual cautions users that all Thöress devices should be placed on stable a stable surface, preferably on dedicated racks and anti-vibration platforms. Otherwise, tube's micro-phonics might be audible, which is a conversion of the cathode and anode vibrations into a modulation of electric signal. Reinhard also advises user not to place his amplifiers close to the loudspeakers. In my system, such large amplifiers unfortunately have to be placed relatively close to Harbeths. To separate them at least to some extent from vibrations, I put them on the Acoustic Revive RST-38H platforms, and on the Vibrapod pads. Because the monoblocks's depth is bigger than the one of AR platform the back side was supported by Vibrapods.

All the cables in the system were made of Japanese copper. I used Acoustic Revive RCA-1.0 Triple-C FM interconnects, Acoustic Revive SPC-3.0 Triple-C speaker cables and Acoustic Revive Power Reference Triple-C power chord. The latter powered the CD Player and preamplifier. For power amplifiers I used Acrolink Mexcel 7N-PC9500.

Sound

CD/SACD

Art Tatum, Piano Starts Here, Columbia/Sony Classical 97 22218 2, "Zenph Re-Performance", SACD/CD (2008)
Derek & The Dominos, Layla, Polydor/Universal Music LLC UICY-40004, Platinum SHM-CD (1970/2013)
Dire Straits, Love Over Gold, Vertigo/Universal Music LLC (Japan) UICY-40029, Platinum SHM-CD (1982/2013)
Frank Sinatra, Where Are You?, Capitol Records/Mobile Fidelity UDSACD 2109, “Special Limited Edition | No. 261", SACD/CD (1957/2013)
J. S. Bach, Cello-Suiten, perf. Mstislav Rostropovich, EMI Classics/Warner Music Japan WPCS-28106/7, "Premium Classics", 2 x Ultimate HiQuality CD (1995/2017)
Laurie Anderson, Homeland, Nonesuch 524055-2, CD + DVD (2010)
Miles Davis, The Complete Birth of the Cool, Capitol Jazz/EMI 4945502, CD (1957/1998)
Pet Shop Boys, Super, Sony Music Labels (Japan) SICX-41, CD (2016)
Peter Gabriel, So, Realworld/Virgin SAPGCD5, SACD/CD (1987/2003)

Dual Function Preamplifier

Headphone amplifier

The multi-functional devices usually fail expectations. That means they do what they promise, but in a "lesser" way. If we combine several products into one, we have to compromise. After all, the general principle of high-end—use separate devices—came from somewhere. Preamplifiers that are supposed to work as headphone amplifier are a very good example. I do not know where these guys making them take their optimism from but I have not yet listened to any such device that without sacrificing the linestage's quality would be able to properly drive the most important types of headphones as well as a dedicated, specialized component.

That is until I heard the Thöress's preamplifier / headphone amplifier. In his case, the name with 'preamplifier' in front of the 'headphone amplifier' is purely contractual, and it follows the logic that without a headphone output it could still operate as preamplifier but without the latter it could not be the former. But from the sound point of view, it might as well be the opposite.

In comparison with the specialized Ayon Audio HA-3, using 45 triodes with an output transformer, so—theoretically—a more versatile competitor, this German device has clearly more to offer. Maybe not in 100% of cases, but in my opinion this product can easily replace Ayon in any system. First of all because its sound is dense, firm, full-blooded. It brings the sound closer to the listener and emphasizes a lower midrange, which "voices" the whole performance. In result, no matter which headphones one uses they will deliver a rich sound with nicely extended bass, and a clear, though slightly warm top.

It was particularly obvious with HiFiMAN HE-1000 v2, a difficult to drive planar-magnetics. It was the second time I heard them playing so dense, so low—the first time was with the HiFiMAN headphone amplifier. Ayon shifts the tonal balance slightly up, and Thöress does the opposite—lowers it, hence this is not a "transparent" performance. Also because the low bass is as well controlled as by the HA-3, nor by number of high-power solid-state amplifiers.

I do not know if this is actually needed. It is a complete, warm, very sensual sound. It's perfectly spatial, which I got with binaural recordings, like from the new Kraftwerk's box, or other having a lot of information encoded out-of-phase, like. Homeland by Laurie Anderson. It sounded fantastic! And when I listened to monophonic recordings like Birth of The Cool by Miles Davis, the version remastered by Mark Levinson, I had the foreground placed very close to me, well defined but naturally soft, pretty.

All headphones I used sounded this way, with emphasis on three main types. Both the Sennheiser HD800 and the Beyerdynamic DT-990 Pro sounded in much the same way as the HiFiMANs. They were not so resolving, they also differed tonally, but they were all perfectly driven, controlled, equally rich. Let me repeat: I have never heard them sounding that good. Which I can also say about the HE-1000 v2.

Only the ultimate resolution provided by the Ayon Audio amplifier and the better defined - but slimmer—bass proved that some elements could still be presented in a better way. When listening to recordings with a double bass, like the great album Tribute to Charlie Haden by Wojciech Pulcin, or cello—one realizes that the German device is slightly emphasizing the lower midrange and upper bass. However, it does so in such a sophisticated and reliable way that we perceive it as a "feature" rather than a flaw. This was true SOMETHING.

Although the tonal difference is quite significant, the HA-3 and the Dual Function Preamplifier as headphone amplifier play in the same league. The latter provides the opportunity to adjust the tone and intensity of the sound. During most listening sessions I put the "Empfindichkeit & Klang" knob to the "1" position, but there is also the “2" position available, which lowers the top and “slims" the bass, the "3" and "6" that emphasize bands extremes. So listener has a choice. The most neutral and simply the best sound, with all the headphones, the amplifier deliver in the '1' position. And only the Beyerdynamics with high bass content required turning the knob to "3".

Dual Function Preamplifier

Preamplifier

It is easier for me to describe devices when I put them on comparison grid with some other similar products that I already tested before. I think this also makes it easier for the readers of High Fidelity because you do not have to start from the scratch if you remember my previous reviews or maybe you listened to the same devices and confronted my opinions with your own. In the case of Mr. Thöress's preamplifier, I shall use two outstanding device: the solid-state Mark Levinson No. 52, and the tube one, with transformer regulated signal that I've been using for the past two years, the Ayon Audio Spheris III.

If I placed at the beginning of the axis describing tonal balance the Mark Levinson, as the most open, the most resolved and fastest device, than in the middle I would place the Ayon, and the German preamplifier on its other side, symmetrically to No. 52. This device delivers a dense, warm sound with an emphasize in the lower midrange. As far as headphones are concerned, I prefer the tone adjustment set on "1", but now I realized that both bands extremes were slightly emphasized with it. Combined with the Soulution 710 the most neutral setting was actually the “3".

This setting provided a beautiful performance—warm, rich, powerful. It's the kind of presentation where the foreground plays the most important part, whether it's a voice, an instrument, a strong guitar or even electronics. We also get a fantastic space, but limited to a "bubble" surrounding us. The preamplifier does not build a deep stage, but rather offers a wide perspective and develops it to the sides and—if that was the idea of the producer—behind us. In this respects it outperforms the above mentioned competitors.

But its performance resembles the sound from the 1950s and 60s. In a sense, that the bass is not very patiently controlled. It's strong, it goes down very low, but it's not the most important thing about it. It seems to be about flow, tone, transitions, tonal subtleties. The dynamics are very good, and that is because it is a big and rich sound that never gets boring. You should know though, that resolution and differentiation are not priorities in this performance. It comes out a bit "by the way", but there is no question that it does not have the ultra-clarity and definition of Mark Levinson or the breath and depth of Ayon Audio.

Dual Function Preamplifier + 845 Mono

System

do not know if you remember the KSS meeting and the test dedicated to Kondo OnGaku? I wrote back then about the smoothness, warmth and softness of the sound I'd never heard before with any other amplifier. Not everybody liked it equally—see the statements of the members of the Krakow Sonic Society—but no one refused the Japanese amplifier of its greatness.

I'm reminding you of this case because Thöress system has its priorities set in a very similar way. It is also a full-blooded sound, unequivocally warm and smooth. Playing Sinatra was putting a piece of silk on my cheek—equally sensual, just as palpable. This is the sound in which the tone plays a leading role, which reminds me of devices made by other great Japanese masters, such as Mr. Taku Hyodo of Leben or Shirokazu Yazaki of the SPEC Corporation. He shares with them the love of fullness and flow of music.

This Thöress will never make you get us upset by how the music you listen to was recorded or released. As if their flaws were somehow masked, removed from the field of view. The highly compressed discs, such as the Pet Shop Boys Super, compressed and having problems with being too bright and contoured, such as Peter Gabriel's So in the SACD version of 2003, sounded with the German amplifier warm, nice and pleasant. It does not, however, play well “despite" of these problems, but it rather moves around them. This is an important distinction because the "despite" version is usually delivered by much more resolving devices.

Same as the preamplifier, also the whole system delivers a warm, powerful, rich bass. The output delivered by the KR Audio 845s was enough to play really loud with the difficult-to-drive Harbeth M40.1. They might not provide an absolute control over to lower part of the band, but that's probably not the point. I think the priority was the continuity of the whole band and basing it on a strong, solid foundation. The sound is so saturated that everything seems large and tangible including the low bass.

Interestingly, despite the unambiguous "tube-like" nature of presentation the vocals are not pushed forward in front of the speakers, nor are they enlarged. If, like on the Sinatra album, they are powerful and rich, but presented in some distance from listener, the Thöress system will present them so. On the other hand, if there is a strong foreground, like with Miles Davis, it is really strong. And if the instrument has a lot of air around it, Thöress does a great job of emphasizing that feature, creating a large soundstage and powerful images—just like on Bach's cello suits performed by Mstislav Rostropovich on a new remaster released by Warner Music Japan on Ultimate HiQuality CDs. BY the way, this year marks the 10th anniversary of the death of this great master.

It was fascinating how deep was the interaction between the instrument's box and the acoustics. It was an unusual harmony, air was vibrating, as if it was inseparable from the instrument itself - even though it was imaged precisely, without the blurring of its edges. It is an "inherent" feature of this system, which I previously heard only with the said Kondo amplifier, with the new, now finalized version of Ancient Audio Grand Monos and Audiopax Maggiore. The Thöress, by the richness of the bass and midrange goes one step further, boosting the sound, exposing emotions.

You will not be bored with this sound. It is not a "hi-fi" or even an "audiophile" sound. There is no impressive depth, no precise edges, selectivity, and even some remarkable resolution. The German system makes sound of different recordings more alike, masking their weaker sides and extracting their internal tension, richness and pulse. What would be exactly the same direction as followed by the above mentioned, Mr. Shirokazu Yazaki, who recently sent me a prototype version of his new speaker filter, referred to as "Real-Sound Processor", for evaluation, and the idea behind the sound of the Brazilian Audiopax system.

It is no coincidence that there are so many references in this sound to the Japanese masters, that Jarek Waszczyszyn (Ancient Audio) goes in the same direction—it is most likely a good direction. The German amplifier, both the preamplifier itself, the headphone amplifier, and the system with monoblocks, explores regions close to expressionism and really "gutsy" sound at the same time. It is difficult to maintain objectivity, because it engages listener encouraging him to abandon objectivity.

Summary

Mt Reinhard Thöress to point out his goals says:

In MY world amplifiers, loudspeakers and all other audio components are just means that allow music lovers to expand their horizons. These are important, valuable tools, but they do not serve as a measure of man's status or a toy one should brag about.

source: company materials

I understand the role of those "tools" not as impersonal cutting tools, but as refined language, conceptual tools. It's about sinking in music, no matter what we listen to. Objectively it must be said that this system adds a bit of weight and warmth to the sound. The resolution is really good, but it does not translate into building clear bodies, textures.

Think of the German system as a carrier of emotion. It's an amplifier that will not leave you indifferent to the music, that will engage you, pull you in, attract attention, but it will also calm you down. It delivers an extremely full, rich sound, as if the purpose is to prove that only SET amplifier can perform in this way. The emphasis is on the lower midrange, but there is also a low bass and a nice top. It presents a great space, building it in the form of a "bubble", also around us. It energizes the air in the room with ease, including it in the created musical world. It offers enough power to drive even large speakers, but you should not exaggerate the size of the room it will play in. It's a beautiful amplifier. And even better headphone amplifier.

Design

Reinhard Thöress's products are difficult to confuse with any other ones. Built like the industrial equipment of the 1950s and 1960s, they combine an industrial look with inevitable nostalgia – after all these days are long gone. And that's probably the designer's intention. The chassis is made of aluminum and colored for something between steel and green, with silver fronts and backs. The chassis features openings that allow proper cooling of the interior.

Dual Function Preamplifier

The Dual Function Preamplifier (DFP) offers six line inputs, three line outputs and two headphone outputs—to choose between the latter, one uses a small toggle switch on the front. Input selection is operated using a knob that looks the same as the other one next to it used to adjust input sensitivity and volume. Three of the six positions of the output sensitivity selector knob are used for—as the company materials say—a subtle change in the tonality. No. 6 is associated with a "loudness" type correction, which is useful for quiet listening when it is necessary to compensate for the non-linearity of human hearing.

All three knobs are well scaled and can be read from a distance. You can also adjust volume using the remote control. The RCA sockets are very nice - solid and far enough apart that any interconnect can be used. There is also a switch to disconnect the electrical ground from the chassis on the rear panel.

The internal design is yet another trip into the past, but with the use of modern solutions. The electrical circuit is hard-wired—no printed circuit boards are used here. Instead, Mr Thöress used auxiliary mounting rails to solder components to them. And you will find there a lot of high quality ones—Vishay resistors and capacitors, WIMA capacitors, oil capacitors filtering anode voltage, etc. The attenuation of the signal is operated by a custom made potentiometer with motor. It is a precise piece of equipment that ensures that the difference between the channels at any point will not be greater than 0.5dB. Next there is the only PCB in this device, with a receiver and motor control.

Most space, like in most high quality components, is occupied by a power supply. It's based on a large EI transformer. It is bolted to the side wall by means of soft elements that suppress its vibration. It is also shielded. Three separate regulated power supplies come out of it, with many filter capacitors.

The amplifier was assembled on two tubes per channel: the United Electron 12HG7 / 12GN7 triode pentode and the Radium Electron Tube 6J5 triode with octal pedestal. The latter was developed in 1937, so it is a contemporary triode 300B. It comes in a metal and glass mug version - here we have the second version. Both lamps are of course NOS type, i.e. they are new, not used, but they were manufactured in the mid 20th century. The lamps were mounted on a thick laminate.

Line amplification features two tubes per channel: a United Electron 12HG7/12GN7 pentode operating in a triode mode and RCA Radiotron Electron Tube 6J5. The latter was developed in 1937 so it's an age-mate of the famous 300B triode. It comes in a metal and glass body version—here we have the latter. Both tubes are of course NOS types, i.e. they are new, never used, but they were manufactured in the mid 20th century. The tubes are mounted on a thick laminate.

845 Mono

While the preamplifier features classic proportions, the 845 Monos are different. First of all, they are very long (deep) and narrow. On the front there are only holes arranged in a "T" shape and an orange power indicator. On the back there is a pair of gold-plated speaker posts, an RCA input and a knob that can be used to minimize hum if necessary. The power tubes are placed on the top of the amplifier. Two NOS EL803S (V2382KB / QDD) pentodes work in the input and as a driver. It is a tube similar to EL84 that was created in the 1960s and originally used to amplify a video signal. They work in parallel and are coupled with the output tube using capacitor. In the output manufacturer used the TRV 845 from KR Audio operating in class A.

Also here most of the space is occupied by the power supply. It features a large EI transformer with two secondary windings, working with rectifier Shottky diodes and a choke for 845 triode. The anode voltage is regulated. The voltage for the latter is filtered via six large capacitors made by Italian company Comar Condensatori. DC heating is provided for the power tube, whereas any residual hum introduced by the heater circuit may be balanced out by adjusting a control knob on the rear panel of the chassis.

The electrical circuit is assembled similarly to the one in the preamplifier—it is hard-wired using the rails. Interestingly I noticed a powerful "double C" output transformer.