Ayon Audio Orthos XS: Audiophile Magazine Review



Audio Weight Lifting: Episode 1


This article is the starting point of a series that could be called my strange audiophile weightlifting exercise. My next tests will focus on some of the most powerful monophonic amplifiers on sale today. Thus, the powerful blocks Orthos XS Ayon should be followed closely by the imposing SPM-6000 Chord, then by the titanic Karan KAM 2000. These power monsters and will come to measure against my more modest amplifiers Orpheus Labs Three M and Luxman M800a (in bridged mode for these).

Although the ultra-demanding loads have become rather rare in the current panorama of high-end speakers, manufacturers continue to offer their catalog some big amplifiers whose power seems simply unreasonable. The relation between the power developed by an amplifier and the sound quality is obviously not implicit. Amps killers like the Apogee Scintilla or some models from Infinity Kappa seem today more of anecdote, or even downright prehistoric, than an audiophile nirvana in which only some big monsters would be entitled. These amps “ster (é) oïdés” evoke nowadays for the vast majority a waste of money as well as an insane electricity consumption whereas the economies of

And yet, raw power remains a prerequisite for many ambitious speakers of low or medium sensitivity, to avoid overloading or clipping. If an amplifier has insufficient power to meet the logarithmic requirements of SPL increases (each 10 dB increase in sound level, eg 90 to 100 dB, requires 10 times as much electrical power), the top and bottom of the wavefront representing the audio signal will inevitably be planed, which will generate distortion output. The amplifier will then activate its protection circuits and remove the overloading signal parts to generate further distortion.

We can of course overcome this problem by opting for high-performance speakers and less powerful amplifiers. Very often, however, this choice represents a thorny path to the grail of high-fidelity given the sensitive demotion of this type of HP high level. Some drought and a fairly poor off-axis response are weak points in many flag systems.

Do not worry, though, that my intentions here are not to sneak a hint of low performance loudspeakers and high power amplifiers. In audio, the possibilities are many and there is no proper royal road, the synergy between the various links constituting your stereo probably remains the key factor. My considerations here are only to highlight the interest of our day to acquire such power blocks, choice among many other possible … if the size of your listening room, the insulation of your home and the tolerance of your immediate neighborhood will allow you. But when you want to achieve realistic acoustic levels in a large room,

The loudness must not be assimilated necessarily to any auditory folly or degradation of the listening conditions. It is above all the distortion generated by the sound reproduction chain that gives this feeling of acoustic pressure too high. At high volume, a system with very low distortion rates ultimately causes virtually no auditory fatigue. I have often had this feeling, for example, listening to demonstrations of German MBL brand systems that are almost always at dull SPL levels. No secret: to reduce the distortion rate, we must work on improving the dynamic range of operation of the amplifier, and therefore aim more powerful. If you’re looking for high fidelity and realism, it is necessary at least to have the necessary power reserves to develop a stereo image may not be life-size, but ample enough that the feeling of being on the place of registration becomes real. In any case this theme will be the focus of this series weightlifter …


KT 150 Tung Sol sheet data

Now back to the new crown jewel of Ayon. Electronist and founder Gerhard Hirt has designed a third and ambitious version of the first iteration of the Orthos blocks with three possible Pentode mountings: KT88, KT120 and the all-new KT150. Just released from the Tung Sol factories this year, this last KT150 is an evolution of the previous KT120 supposed to deliver an impressive power of 35 to 40 watts per tube, while reconciling refinement and transparency. 400 watts of pure class A push-pull pentodes seems a power beyond standards, which was the prerogative of some OTL schemes and some prestigious achievements at Manley. What about Orthos XS? We will discover in the following pages.

There are of course even more powerful tube amps such as the Siegfried VTL and their 800 watts, their predecessors VTL Wotan and their 1,250 watts or even the VAC Statement with 450 watts monophonic block …

On the other hand, these achievements are still far less democratic than the Orthos XS blocks, which are almost like affordable devices. Indeed, past a certain level of power, there are no limits in the prices recommended by manufacturers of high-end tube amps. As a reminder, the VAC Statement 450 monophonic was priced at $ 80,000 a pair, while the Siegfried VTL was introduced at $ 65,000. In this race to excess, the Orthos XS are considered reasonable students, even if the 400-watt KT150 pentode (300 watts in KT120, 250 watts in KT88) claimed by the Ayon blocks, as well as the judgment of Gerhard Hirt (who simply think of them as one of the best KT88 amps ever designed), makes them play in the same yard as their prestigious elders.

As usual, the chief designer Gerhard Hirt applied his personal touch to this flagship of pentode amplification by implementing (among other things) very short circuits, a total absence of feedback, no components semiconductor in the signal path, a large power supply capable of holding very low impedance loads, and a double grounding system …

The Orthos XS are delivered in two raw wood crates of very basic finish but robust enough to guarantee an optimum level of protection during transport. However, we see that Hirt did not immobilize crazy sums in the packaging, and that his concerns focused on the only quality of manufacture of the product.

The two anti-vibration frames made of high-quality brushed and anodized aluminum are assembled by hand to ensure an exemplary level of finish. The chassis of the previous models has been optimized for the XS series to ensure better heat ventilation. Its four aluminum legs are also used to absorb the resonances. The main inscriptions on the front and back are engraved on aluminum. On the front panel, a bright “Ayon” logo flashes until the thermal stabilization phase is complete after the unit is turned on.

The fourteen tubes of each mono block are numbered, after being duly tested and the bias adjustment made, and must be placed each on their specific base. The new KT150 pentode is very slender compared to its ancestor KT88. Both Orthos XS also display an image of very elegant, extremely well-finished devices, like the rest of the Ayon product range.


The Orthos XS has a fixed bias circuit that allows it to control each tube of power without having any negative impact on the sound quality. It is thus more sophisticated than the automatic or semi-automatic bias control systems that can be found on a number of competing brands. The Orthos XS fixed automatic bias circuit also includes a sophisticated electronic protection device that starts as part of the tube test program when the device is turned on. In case of excessive polarization current or a defective tube, the high voltage switches off immediately, either via the optocoupler circuit or an A / D converter.


What is fixed polarization?

There are two main types of polarization: fixed bias and automatic polarization. The fixed polarization does not mean that the bias is not adjustable, in fact, it usually means the opposite. The automatic polarization is usually fixed and not adjustable, while the fixed polarization is adjustable with a small trimmer, or “trimpot”.

The fixed polarization means that the tube is biased (biased) by a DC voltage, which is generally negative, applied to the grid of the tube. By adjusting the negative gate voltage, the bias current (bias) will increase or decrease in the same direction as the bias voltage. In general, when the bias voltage becomes more negative, the bias current becomes smaller, and the tube is said to be polarized more “cold”. When the tension of polarization becomes less negative, always under the continuous 0V, the bias current becomes

bigger and the tube is said polarized more “hot”. Because a tube has a “normally operational” structure, it allows current to flow through the cathode tube at the anode when the gate is at 0V to the cathode. The tube can be blocked and the current stopped by making the grid potential strongly negative with respect to the cathode. The tube can also be polarized by referencing the gate to ground, or at 0V DC, and applying a positive DC voltage to the cathode. It is the same as putting the cathode to the ground and applying a negative DC voltage to the gate, because it is the potential difference between the gate and the cathode that determines the value of the bias current (bias) that passes through the tube.

Since the tubes have a “normally operational” structure, a trick can be used to bias them without applying a negative voltage to the gate. If a resistor is placed between the cathode and the ground, and that the grid of the tube is referenced to the ground (generally by connecting a resistance of great value between the grid and the mass, of the order of 1Mega Ohm), the tube will try to conduct a strong current from the cathode to the anode, since the gate and the cathode are initially at the potential of the mass. Thus, this cathode current will cause a voltage drop across the cathode resistor, thereby creating a positive voltage at the cathode relative to the gate. As the voltage of the cathode is now positive with respect to the gate, the current will decrease, and the tube will tend towards its limit (cut-off). A point of equilibrium will be quickly reached,

where the increase of the current will be perfectly compensated by the increase of the cathode voltage, and the bias current will stabilize at a particular value. This value will remain constant until the resistance value is changed, or a tube with different characteristics replaces the old one. Thus, it is possible to set the desired bias point by varying the value of the cathode resistance.

When is the fixed bias used instead of the automatic bias?

Since automatic polarization removes the need to provide a negative voltage, why do not all amps use auto bias? Well, the automatic polarization is not without defects. It turns out that to keep the bias voltage on the cathode constant while the input signal is changing, the cathode resistance must be bypassed by a large capacitor. In reality, this capacitor bypasses the AC voltage of the signal to ground, allowing the DC voltage to remain relatively constant. If the capacitor is removed, the AC voltage of the signal will be superimposed on the DC voltage at the cathode, which will subtract from the potential difference between the gate and the cathode and thus reduce the gain of the stage. The problem arises when there are large amplitudes of the input signal and the average DC voltage of the cathode changes. This causes the polarization point to shift, usually towards a more “cold” polarization point. This displacement of the polarization can be heard, but it is sometimes desired for a guitar amp, because it adds harmonics.

If the displacement of the bias point is large, the tube will reach its cut-off and create a high rate of crossover distortion. In addition, the current flowing through the cathode resistor necessarily generates a large bias voltage on the cathode for proper use of the lamp (typically 30-50 volts for the most powerful power tubes). This voltage is subtracted from the total voltage of the anode, which reduces the available power output. Between this voltage drop and the displacement of the polarization, the output power with automatic polarization is reduced when compared with the fixed bias method. In conclusion, fixed polarization is used for high power amps (50W and above),

and automatic polarization is generally used for smaller power amps. The preamplifier lamps are almost universally polarized with the automatic polarization method, because they are used for signal amplification, not power amplification, so the bad effects of automatic polarization are no longer as important. Also, the automatic polarization makes the circuit less dependent on the characteristics of the lamp and more respectful of the polarization point. This allows lamp replacement without having to repolarize the floor in question. Power lamps that are polarized by the automatic polarization method should always be set when changing lamps.

After 45 minutes of operation,the tubes of the Orthos XS reach their optimum operating temperature, and the unit carries out an additional polarization reference check which is confirmed on the rear panel display after the power is turned off. The measured polarization values ​​are stored and used as a reference value for the next use to always guarantee the best balance point according to the level of wear and aging of the tubes. If the polarization control detects that a tube can no longer reach its optimum value or that its state of perfect operation is no longer guaranteed (bias current showing a value too high), the high voltage is cut off automatically, the logo flashes , On the top plate, an analog bias meter provides direct control of the bias value for each tube through the selector on the back panel. Above the meter, a mode switch allows easy switching between triode and pentode modes. As it is difficult to predict exactly, which mode of operation will best fit his system, given the number of parameters involved, Ayon urges to try both modes (triode and pentode) and see for yourself -even. With my Vivid Audio speakers that are not of extreme requirement, the triode mode proved the most convincing. Given the specifications, the triode power level (300 watts) is certainly enough to handle almost any load, while providing a level of finesse and delicacy that often seems inaccessible to large pentode amplifiers.


On the back panel , there are some typical details of Ayon electronics: an earthing switch for better noise rejection, and a current polarity indicator (electrical phase). The output transformers of Ayon are also quite impressive. The output transformer with very wide bandwidth provides all the energy necessary for low frequency control while maintaining a vivacity and exceptional fluidity in the mid-high. The power and output transformers are insulated to ensure high immunity to unwanted waves and vibrations.

The Orthos XS operates in pure A class in push-pull pentode or triode mode. The power supply has been implemented with great care, although the push-pull design is naturally more tolerant. Quality has thus made a significant leap forward, thanks in part to the new multi-point regulated power supply. The progress achieved lies in a wider dynamic range and better bass performance, with a tighter bass. The new diet also brought greater liveliness as well as a noticeable increase in joint and micro-dynamics. The sophisticated input stage provides an infinitely low noise floor. The filtration of the feed has been strengthened and dedicated transformers, as well as Gerhard Hirt uses electrolytic capacitors with large storage capacity to compensate for the loss of filtering by using resistors instead of inductors. Each Orthos XS has two low-noise power transformers, encapsulated for better damping and shielding against radio and electromagnetic interference (RFI / EMI). A sequential soft-start device also extends the life of the tubes. The passive components used are generally of superior quality such as high-speed coupling capacitors, gold-plated circuit board, or even tube supports with copper and beryllium contact rings.

The specifications give the bandwidth for 8 Hz – 70 kHz at 4 and 8 ohms, an input impedance of 47 KΩ, an input sensitivity of 1200 mV at full power, a signal-to-noise ratio of 98 dB, 35 x 61 x 25 cm and a weight of 50 kg per block.

Impressions of plays: To my ears, the new Orthos XS amplification blocks have proved extremely transparent and detailed, especially on low-amplitude signals. This high degree of transparency is not achieved at the cost of artificial brightness or any hardness. Unlike many of the KT88-based schemes that seemed to me to be perfectible, the big Ayons blocks proved to be models of delicacy and pure refinement. They have also been sovereign in the management of macro dynamics and transients. The stereo image is both wide and deep puts into perspective an impressive amount of detail, without ever being able to feel a tension in these monsters of controlled power. Compared to my Orpheus Three M blocks or my Luxman M800a (operated bridged), Orthos XS may have a slight tendency to smooth the granularity of music, including violins and vocals, which seems normal for amplification power tubes. But they skilfully avoid putting too much emphasis on mediums or a signature that might seem too euphonic. The Orthos XS are undoubtedly tube amplifiers with the best articulation I have tested so far.They have an ability to pass transients almost staggering, foiling the traps that can overwhelm the recordings of great orchestral masses, as I could feel listening to the third symphony of Saint Saens. Speed ​​and sense of rhythm are two of the attributes that come to mind when I think of Orthos. The Ayons manage to achieve this tour de force to be extremely delicate and natural while delivering articulation and precision of the foreground. Both Orthos XS also have an impressive power reserve and never seem to bother. I never had the feeling that the Ayons were starting to stress and getting closer to their level of clipping. My Austrian hosts also demonstrated a great silence of operation, with a stable sound stage, positioning each instrument very precisely. The new Orthos XS have the ability to have a subjective level of silence that is quite comparable to the best transistors, like the big models of Mark Levinson for example. Clarity and transparency were of course expected for devices in this price range. But I was still pleasantly surprised by the presence revealed subtle ambient details, very slight dynamic variations that often go to the door, even with expensive devices priced …  The tonal accuracy is not usually the strong point of an amp made of big pentodes. The potential buyer of a pair of Orthos XS should probably not expect to find the fineness of the medium of a single-ended 300B. Gerhard Hirt nevertheless managed to refine a quality of timbres that I would be above average for this class of amplifier. Of course, the quality of the stamps may vary depending on the other links you will associate, including the preamplifier. The Orthos XS have a kind of honesty in the high medium that allows to obtain a precise three-dimensional image and a good restitution of the ambient information. They are also quite linear and have never given me the feeling of overemphasizing the medium-high register. The grave register is rather rich and superbly defined. It is never too prominent and does not bring a mask effect on the rest of the bandwidth. The precision of the stringed instrument attacks was particularly convincing. I thought that my Orpheus Three M blocks were among the best amps to restore such energy and spontaneity in the handling of transients, but the Orthos XS did just as well with the added bonus of better fluidity. My two Luxman M800a amplifiers provide less power (although this point is questionable when operated in bridged mode) but a little more density and texture on stringed instruments than Ayon or Orpheus Labs.


Audible differences between triode and pentode modesare relatively subtle. The triode mode delivers a little more opening, gives the feeling that there is a little more air between the different desks, and therefore a little more natural. The pentode mode seems a little more dynamic, with bass more supported. This seems to me to be more a question of taste than a real compromise between power and sound quality. 300 watts should be able to power most speakers available on the market. Opting for the 100-watt supplement will only be useful for a few very difficult tasks. In both modes, Orthos XS remained precise and delicate. They seemed to me much more civilized and easy to implement than other big tube toms like CAT JL2 or JL3 … Their great power is always distilled with great ease without ever giving in brute force. I have never reached a stage where I could have the impression that the amplifiers lacked energy!

On “Hush” [Emotive Records] by Sarah Lenka, the jazz club atmosphere is superbly reproduced, with a lot of clarity. The Ayons particularly emphasize the beautiful presence as well as the fragility of the young singer. Compared to my Luxman M800a, the stereo image is wider and the sound is more liquid. The medium of Ayon is however not as beautiful and hot as that of Luxman, but still more neat than that of my Orpheus Labs. With my Japanese amps, the sound acquires a kind of organic density that remains inaccessible to the other two pairs in the presence. In terms of naturalness, I would say that it was the Ayons that were the most realistic followed by Luxman, then Orpheus Three M. In fact, the Orthos XS play in a register closer to a single-ended with an emotional dimension superior to the other two. Sarah Lenka’s voice on the Orthos XS is more holographic than with the Luxmans who are very much embodied in their own way but with a slightly more projected sound. In the end, the Orthos XS did not seem ethereal like other tube amps that I could try on my Vivid K1 but they turned out to be more holographic and detailed in the low medium.

Listening to “Peer Gynt” directed by Paavo Järvi [Virgin Classics], the depth of image was very impressive, while the accuracy and speed of the transients were simply exceptional. My Orpheus 3 M are serious candidates on this list, but the Orthos XS have managed to beat my Swiss amps, demonstrating a natural ability to pass the most complex messages without an ounce of aggression, and returning my transistors to their dear studies … The purity of the treble and the resulting three-dimensional image send you directly within the musical event. Powerful, taut bass sounds like live music that gets you more involved in listening.

On “Cantate Domino” from the Oscar Motet Choir [Proprius],the Orthos made a nice and realistic image of this very natural analog recording, captured with only two Pearl TC4 pickups and a Revox A77 recorder. Everything seemed perfectly controlled by the Orthos, be it the precise focus of each voice, the extension at the bottom of the spectrum or the sensation of depth. The Ayons proved to be very efficient in transcribing the acoustics of the recording site as well as a profusion of micro-details. On each track of this audiophile recording, despite his respectable age, I was able to feel the atmosphere inside the church and the air expelled by the organ. Church organs are certainly a complicated thing to reproduce for a hi-fi system, and especially terribly demanding for speakers and amps. Most audio systems can not reproduce the correct intensity of all the bandwidth and the first two octaves seem too often withdrawn, or exacerbated excessively, with a huge mask effect on the low medium that is so rich in shades. A very stable amplifier, combined with soundly designed speakers capable of descending sufficiently low, allows to size the organ to the right scale while highlighting its subtlety of timbres. The Orthos XS were very comfortable with this exercise, opening a large sound stage, well outside the triangle formed by my Vivid Audio K1. correct intensity of all the bandwidth and the first two octaves seem too often withdrawn, or exacerbated excessively, with a huge mask effect on the low medium that is so rich in nuances. A very stable amplifier, combined with soundly designed speakers capable of descending sufficiently low, allows to size the organ to the right scale while highlighting its subtlety of timbres. The Orthos XS were very comfortable with this exercise, opening a large sound stage, well outside the triangle formed by my Vivid Audio K1. correct intensity of all the bandwidth and the first two octaves seem too often withdrawn, or exacerbated excessively, with a huge mask effect on the low medium that is so rich in nuances. A very stable amplifier, combined with soundly designed speakers capable of descending sufficiently low, allows to size the organ to the right scale while highlighting its subtlety of timbres. The Orthos XS were very comfortable with this exercise, opening a large sound stage, well outside the triangle formed by my Vivid Audio K1. combined with soundly designed speakers capable of descending sufficiently low, allows to size the organ at the right scale while highlighting its subtlety of timbres. The Orthos XS were very comfortable with this exercise, opening a large sound stage, well outside the triangle formed by my Vivid Audio K1. combined with soundly designed speakers capable of descending sufficiently low, allows to size the organ at the right scale while highlighting its subtlety of timbres. The Orthos XS were very comfortable with this exercise, opening a large sound stage, well outside the triangle formed by my Vivid Audio K1.

Changing to more sophisticated but more compressed music, like Tears For Fears’ Elemental, [Mercury],Orthos XS develop less testosterone than their transistor rivals but are not out of the box. No therapeutic contraindication vis-à-vis pop or electronic music, the Ayon are able to hold the pace and make you stomp your foot … Listening to the latest installment of Tears For Fears, which sign the departure of Curt Smith, can be done at very high levels and Austrian amps continue to offer a very clean and consistent, deploying an XXL sound stage. Very often, large tube amplifiers do not have the density required for listening to pop-rock music to be totally engaging. The Orthos XS arrive there, and this deserves to be emphasized.

To conclude,Orthos XS monophonic blocks disrupt the hierarchy of large tube amplification by reaching new performance thresholds, rarely achieved at this level of budget. Their high resolution, their capacity to modulate the most intense as the most minute dynamic variations, as well as their ability to transcribe the emotions, make devices in all remarkable points. Thanks to their oversized power supply, Ayon monophonic amplifiers are able to control the most complex loads without flinching. The 400 watt pure class A can be enjoyed in all circumstances: you like to listen loud or very moderate volume, Orthos XS distill the same quality of sound, able to transcribe the smallest dynamic variations on their first watt.

Leur circuit basé sur des liaisons ultra-courtes permet de conserver une transparence et une vivacité de premier plan. A l’instar des héros de la mythologie Grecque ou Germanique, ces nouvelles terreurs de l’amplification à tubes ne craignent pas la concurrence. Proposés à 18.000 € en France, ils ne seront pas à la portée du plus grand monde, mais quiconque envisage de dépenser entre vingt et trente mille euros dans une amplification ultime devrait mettre les Orthos XS sur sa liste d’écoutes prioritaires. En tant qu’aficionado de l’amplification de puissance à transistors, je serais pourtant capable de vivre pleinement heureux avec ces amplis. C’est pour cela que je leur ai décerné une très chaude recommandation d’achat sur 6moons.com, et que je réitère en ces pages !

Joel Chevassus – November 2013

Equipment used for the test bench:

Source: Esoteric K-03 + Esoteric G-02, Apple Imac Lion Osx / Audirvana, Trends UD-10.1, OSX MacBook Lion + HiFace USB to S / pdif.

Amp / Preamp: Rogue Audio Hera II, SPL Volume2, Coincident Technology Statement Line Preamplifier, Orpheus Lab Three M, Luxman M800a 2 (bridged), Trends TA-10.2.

Speakers: Lawrence Audio Violin (on loan), Vivid Audio K1.

Cables: Skywire 2020 Digital, Natural Live Audio 8 MK2, Audio Art SC-5 SE HP, Grimm Audio TPM, HP Audioquest K2, High Fidelity Cables Enhanced – Modulation & HP – (On Loan).

Power cords: Audio Art Power 1 SE, Oyade.

Price of the tested equipment: 18.000 €.

Website: https://www.ayonaudio.com/