August 2015



World Premiere!
Ayon Audio Crossfire EVO Monoblock Power Amplifier
Ayon Audio's Crossfire Evo produces an amazingly rich, tuneful sound with tonal balance.
Review By Wojciech Pacuła

  When we carried Ayon Audio's Crossfire Evo monoblock amplifier for review to my apartment on the fourth floor, my mind flooded with memories of a Germany reviewer that uses Ayon Audio's Epsilon mono amplifiers for quite some time. He use them in both his mastering work while preparing vinyl re-issues and for reviewing purposes. His amplifiers use eight KT150 tubes each to produce sound. Attendees of the Audio Show 2014 in Warsaw (Poland) could find that out for themselves listening to how well these amps handled the mighty Dynaudio Platinum Evidence loudspeakers. So while going up the many floors to my home, Ayon Audio's Crossfire Evo monoblocks might not be particularly heavy since most of the weight is concentrated on their backs due to the large transformers. There are two power transformers as one powers up only the output tube, as the other serves for input and driver tubes. All transformers' housings are filled with damping material. These transformers are very nice, capped with shiny housings of the two large power transformers and a huge output transformer. Carrying them upstairs isn't that easy!

Yet, as we found out, it was doable. It gets even more interesting when one takes a closer look on this latest addition to Ayon Audio's range, reviewed here for the first time in the world. They sport a long chassis, weight 40 kg a piece (88 lbs.), and as I said earlier deliver 35 wpc from a single power tube. That's how much power one of these special A82B triodes is able to deliver! They are custom build according to Ayon Audio's specification by a company that derives from a Czech manufacturer Tesla. These tubes are larger than a classic 300B, yet smaller than other larger tubes like the 211/VT4C and 845. Naturally they sport gold-plated pins and ceramic bases to achieve the very best in sound quality.

The A82B vacuum tube requires significant gain from a driver tube. Gerhard, the chief designer at Ayon Audio, uses different drivers for his SET amplifiers. For the Crossfire Evo, a newly developed triode AA20B is used. It is smaller than AA82B and has almost identical shape as the 5U4G rectifier for this amplifier. All tubes are branded with Ayon's logo and are the results of Gerhards cooperation with this Czech artisan company (tubes are still made by hand). Two Soviet NOS tubes – triodes 6SJ7 – work in amplifier's input stage. These are placed inside metal cups and are used by Soviet military for their very low microphonics and resistance to radiation.

A Few Simple Words From Gerhard Hirt, Ayon Audio's CEO
Wojciech Pacuła:  Please tell me about AA20B and why you deiced to use this tube.

Gerhard Hirt: It is a DHT (direct heated triode) tube, which I think is the best way to drive such a high power SE triode tube like the 82B. We use it for the Crossfire Evo driver design (AA20B) plus only one very special resistor (Vishay non-magnetic type) and one coupling cap within the signal path to drive to 82B. It is a very short signal path, with all components beginning from the transformer, choke or AA20B itself, must be perfect matched together. Also, there is zero global or local negative feedback engaged. The next advantage of the AA20B is that we make them in-house and thus we can control the electrical parameter and the quality. The tube is direct heated and has a large vacuum bulb, which is always an advantage for a big soundstage. With the AA20B as a driver, it allows us to operate only with one gain stage!

Wojciech Pacuła: Tube rectifier is just for the output tube or for all of them?

Gerhard Hirt: With the AA5U4G we can use it only for the pre (6SJ7) and driver stage (AA20B).

Wojciech Pacuła: What was the most important thing you wanted to achieve with Ayon Audio's Crossfire Evo?

Gerhard Hirt: The "heart" of the Crossfire Evo design is a special driver tube and an extremely short signal path plus of course the very powerful 82B. This combination allows the Crossfire Evo to drive very common speaker designs of medium sensitivity with enough power and punch. The major target was also to create a big 3D soundstage that is very liquid and airy.

Wojciech Pacuła: What genres of music do you listen to within your home?

Gerhard Hirt: I am listing a wide range of "real" music and am always hunting for good recordings in combination with impressive musicians and wonderful interpretation. Music  with soul and emotions, as it doesn't matter if it is on LP, CD or High-Resolution file format! I do not like so much of the so-called "super recordings" because, mostly, I can't listen to them because their musicianship and their interpretation are mostly poor.

Build Quality And Operation
A very solid chassis is made of thick aluminum plates, which are fixed together in the four corners with aluminum quarter rounds. On the front there is Ayon's backlit logo. After one switches the amplifier on, with the switch placed underneath, the logo blinks for some time. At the same time the Mute LED is on. This indicates that an automatic procedure in running tests on all vacuum tubes as the highly regulated voltage is slowly raised. Once the tubes' filament reaches a correct temperature it also starts to supply voltage to the tubes' anodes. The whole sequence takes around 60 seconds to complete.

When the amplifiers are turned in for the first time, the “intelligent bias” process called Auto-Fixed-Bias, needs to calibrate itself. This process is necessary in order for amplifier to “learn” the voltage delivered from a particular power outlet. Only after that it is able to determine a proper anode voltage. If a user doesn't run this procedure, after four hours the amplifier will turn itself off and then run calibration by themselves. This entire procedure is run by a highly advanced circuit that is controlled by a microprocessor. It is nothing like other auto-bias systems used in many other amplifiers. As it says in the owner's manual, this system has nothing to do with semi-automatic or classic fixed-bias systems. It operates completely outside the signal's path. Due to Ayon Audio's solution, the vacuum tubes always work within their optimal conditions and are protected from damages. This also helps to ensure each tube's lifespan.

All this might sound complicated in theory, yet in a real world all we have to do is push a button on the back of each amplifier which starts the initial, one-time calibration process. From this time on, we just turn each Ayon Audio Crossfire EVO monoblock amplifier on and off as one would do with any other amplifier.  Now all that is left to do is to deliver signal via unbalanced WBT NextGen RCA or balanced signal XLR sockets, connect your speaker cables to the fantastic WBT NextGen speaker posts you're your music amplification system is ready to play. These SET amplifiers are not fully balanced in design, so Ayon Audio says they prefer an unbalanced signal since a signal delivered via balanced XLR inputs needs to be altered.

So to summarize, Ayon Audio's Crossfire Evo are a pair of mono amplifiers, working in a pure Class A. These are SET amplifiers with a single power tube in each channel working without negative feedback (neither global, nor local), with the current delivered to each tube being completely controlled by a microprocessor for optimum performance. That's what we like best!

Ayon Audio Crossfire EVO Design
The power supply section is also quite complex. When I opened chassis I counted six chokes – each tube has its separate one, and input tubes use even two of these. One will also find a large bank of capacitors and a few independent diode bridges. These supply each tubes' filaments and anode voltage that are rectified by a 5U4G. tube rectifier. All tubes sit on the top cover together with a small VU meter that provides the user with information concerning the value of said bias. Ayon Audio uses high quality HD Synthetic Compound Material tube sockets with rhodium-plated pins. It seems that they were made by Ayon themselves. Although the power supply circuit and a microprocessor controlling circuit are mounted on PCBs, the gain stage uses point-to-point wiring connections. All inner-stage capacitors are oil silver-gold Mundorf capacitors that are very nice indeed!

Test Method
I have been using Ayon's preamplifiers for few years now, including all three versions of Polaris linestage and Spheris III. I chose it after listening to many top preamplifiers from many different brands. Although there were some other very tempting options, it was decided that this Austrian product offered the most convincing set of features and very amazing performance. For this review of the Crossfire EVO came the signal from their Spheris III via unbalanced Acoustic Revive cables (from their latest Triple-C FM line). Signal from my CD player to linestage was delivered via Siltech Double Crown interconnects. Speaker cables were my trusted Tara Labs Omega Onyx. Amplifiers were placed on  Acoustic Revive RST-38H platforms and additionally on Franc Audio Accessories Ceramic Discs – I had to use these as the length of amplifiers was slightly bigger than each platform.

The amplifiers' operation is completely silent as after one hour of use you'd have to place your ear very close to a driver tube to hear a very quiet noise, in part generated by a linestage. During all that time with amplifiers there was never had any problems, neither with starts, nor with any stage of operation. Fit and finish is simply fantastic! I compare these amplifiers directly to my Soulution 710 power amplifier (recently replaced by their 711). They drove my Harbeth M40.1 loudspeakers that are placed on Acoustic Revive Custom stands. As for power cables, I chose the impressive Acrolink Mexcel 7N-PC9500.

Neither myself nor Gerhard of Ayon Audio knew what to expect. Gerhard, because of several unknown aspects like acoustic environment, speakers and source (fortunately, at least he knew a linestage pretty well). Me – because I knew nothing about the latest generation of his amplifiers as have never tested one before. On the other hand, Gerhard followed everything I wrote about his products and sometimes he surely also read some other articles that caught his attention. I, on the other hand, had a chance to listen to the third generation Epsilon mono amplifiers during Audio Show in Warsaw, and to Crossfire Evo in Munich during HIGH END Show. But I had never listened to any of them here within my home audio system. So on one hand we were wondering what would happen, and on the other we had some expectations and preconceptions. It seemed that we were both wrong. I could be absolutely sure only on my part, obviously. But having seen Gerhard's reactions when we listened to few albums… I would say that he also felt the same way. What's more, after two hours, when Gerhard had to leave, I came back to listening to these amplifiers and my impressions did not change a bit. Nor was there any change during the following days of continuing my adventure with Crossfire EVO.

Audio Reflections
I'd like to explain myself. Doing my job within a professional manner dictates repeating the same procedures for each test for each product. It also means that each time my main goal is to describe the sound of a particular device and only then to assess it. As far as description of the sound, it might be largely disassociated from a person as an assessment may be a rather personal affair. Despite my best efforts, experience also influences what I do and provides a base to my assessments on things pervious learned. So when I see and hear SET, I think about Ancient Audio Silver Mono SE (two 300B per channel), Kondo Kagura(two 211/VT4C per channel), Triode TRX-M300 Reference Edition (one 300B per channel) and Phasemation MA-1000 (one 2A3 per channel). Surely there were also others, but these four are the ones that I remember best. All of them work in a pure Class A, use (different but still) triodes working in SET configuration (SE or PSE), and all are mono amplifiers. Each sounded differently and yet they all had more in common with each other than with any other devices to my ears within my home audio system. Ayon Audio's Crossfire Evo monoblock amplifier is different.

Tonality - A Case Study
So first of all tonal balance, as presented by Ayon Audio's Crossfire EVO, is set bit lower than some people may be accustom to, although is it not that unusual for vacuum tube devices. But most of them achieve that by delivering a warmer sound with a rather softer/rounder leading edge. Subjectively, we perceive such performance as calmer, quieter, and with a less aggressive treble with perhaps smaller-scale volume levels. That's how many tubes with standard high quality output transformers sound like when in SET configuration. By the way, many vintage amplifiers perform this way as well. Perhaps that is why they can be so seductive and those who fall for these amplifiers may find others as sounding too aggressively. One has to realize, though, that this is only one of possible strategy, yet a remarkably attractive one. Having a certain amount of money and facing such a choice I would also be considering purchasing one such device and enjoying them (perhaps) for the rest of my life. But we need to be aware that this is not the way to achieve the highest sound fidelity, which, I believe, is the whole point of perfectionist audio. SET amplifiers offer something different in return – the absolutely top amplifiers, and in my opinion these are the SET ones, go beyond 'hi-fi' sound. They combine precision and fidelity with a natural richness. There is one problem, though. As to have the best of the best like Ancient Audio and Kondo, one has to be ready to spent a crazy amount of money to purchase them.

Ayon Audio's Crossfire EVO mono amplifiers offer this type of performance: they are amazingly resolving yet their tonal balance more neutral. It creates an impression of a glorious big sound without even as much as a hint of any coloration. This powerful, rich if you will, perfectly defined bass and low tonal balance don't mean that there is any emphasis on any part of the frequency range. In cases like this one, a top quality and remarkable device, this effect is achieved via outstanding resolution, phase coherency, and most of all by a perfect reproduction of harmonics that are a base for instruments' resonances. This includes electric instruments as the recording dictates.

The Ayon Audio Crossfire EVO easily handles both electronic music like from Lisa Gerrard's The Silver Tree album and purist acoustic recordings like Venecie Mundi Splendor performed by La Reverde. I also played Ultra by Depeche Mode and while I was totally immersed in music, I also appreciated the sound quality of this album as released in the 'Blu-spec CD2 version'. I could easily recognize the guitars' drive, depth and density. Am absolutely sure this album sounded much better than ever before.

This was also supported by fantastic sounds of high definition. When talking about details and nuances, one describes what one knows from a hi-fi world. These are important elements of the sound, important components of a greater whole. But when it comes to high-end, top-high-end in particular, mentioning details or nuances – that may be in a very poor taste. Details and nuances simply are there, as they should be, what is very important is a level up, which is based on these elements. In Ayon's Crossfire EVO they build up in interesting, nicely differentiated sound depending on the quality of recording, with a listener-friendly presentation. I did not find a single recording that would have sounded unpleasant played by these amps. Having said that, I need also to clarify, that if there is some issue, like an emphasis on vocal's attack phase, or just vocal that is bright sounding – like Leonard Cohen's on his last album – these amplifiers won't hide that. If you want an amplifier that can sugarcoat such recordings, Phasemation or Triode might be a better choice.

Ayon, just like Kondo and Ancient Audio, play such pieces differently as they deliver what's there in the recording. Hats off for Ayon Audio! Hats off because despite the fact that these amplifier clearly show the weakness of certain recordings, their performance is nearly always enjoyable as within a properly mastered album. We always accept it as it is. I loved every album played despite the fact that some were recorded with boomy bass, some with bright vocals, and others that lacked 'air'. Ayon clearly pointed out problems with trumpet timbre on certain jazz recordings, but it was me, the listener, who could decide whether this issue bothered me or not. The decision was mine alone, yet was not forced upon me.

An Issue Of Power
When arranging this review, Gerhard and I exchanged quite a few emails discussing an issue of output power required for my room. Matching an amplifier with loudspeakers, one's room size and acoustics plus music preference is key. This key consideration is for anyone who desires to create a serious audio system offering top-flight performance. The common belief is that SET amplifiers should be paired with high-sensitivity speakers, preferably with horns. Without delving deeply into this issue, let me just say that I don't agree with that. Low-power amplifiers, like all aforementioned SET ones within this review, but also some others were able to deliver performance loud enough within my room despite the fact that Harbeths were surely not an easy load. Obviously they all had some problems in bass range, some more serious ones, some just small ones. But in general they contradicted that normal audiophile belief to a great extent. And, let me repeat one more time, Harbeth M40.1 were not an easy load. And yet the more powerful amplifiers connected to these speakers, the better was the performance. They sound amazingly with my Soulution 710, and sounded even better driven by the incredible Naim Statement NAC S1 preamplifier and NAP S1 mono power amplifier as reviewed here.

An exception from this rule are tube amplifiers that sport high gain output stages and are able to deliver high current to the loudspeakers. In a case of such a design it seems irrelevant, as what we have here is a voltage gain stage. And yet now, for the third time in my life, I witnessed a situation where a SET amplifier, this time with a single output tube, delivered a better defined, more powerful bass than most solid-state amplifiers I ever listened to. Attack, slam, dynamics, sustain – brilliant in its naturalness, and fantastic decay kept me each time I played another record on my toes waiting for unexpected to happen. One thing I haven't mentioned yet is the very open sound. Treble did not seem to be rounded nor too warm, which was a case with most previous Ayon Audio amplifiers. It was one of the things that could have steered my opinion towards amplifiers based on the 62B or 82B vacuum tube previously.

A Confession
I have to say it and am sure that Gerhard will understand, as he realizes that test are conducted also in order to find a way to improve current designs. Although I always respected his achievements in the field of SET amplifiers, as these were the apple of his eye, I could never fully accept the concept of sound they proposed. They delivered open and detailed sound, like solid-state amps, offered exceptional dynamics, yet they did not provide what I considered the advantages of vacuum tube devices. Why would I want a tube amplifier that doesn't sound like a tube, but as solid-state? That is also why I always enjoyed quite a bit of listening to Ayon's amplifiers using beam tetrodes like KT88, and now KT150, in push-pull configuration.

Summary
Ayon Audio's Crossfire EVO vacuum tube monoblock amplifier delivers a better performance than any other amplifier Gerhard ever created previously. It combines the virtues of push-pull, SET and solid-state. Everything is mixed in proper proportions, perfectly working together. Actually, it would be difficult to point out which features of the sound came from which type of a design, as the amplifier's performance is simply perfect and thus couldn't care less about losing time for in-depth analyses to find that out. The Crossfire EVO delivers an amazingly rich, tuneful sound with tonal balance set lower then usual. It is highly resolving and wonderfully defined while it impresses with a leading edge and explosive dynamics. Despite relatively low output power, it is able to drive large loudspeakers to a high SPL. In a large room, with particularly 'difficult' speakers, it might not work that well and these are things we have to accept with 35 watts of output power. If we manage to keep proper proportions, which are not influenced by some preconceptions, we'll be thrilled with the remarkable way these Crossfire EVO amplifiers drive our loudspeakers. This, along with Ayon Audio's Spheris III linestage, are the best devices Ayon Audio has released during the last, say, 10 years. These monoblock amplifiers are also one of the best I ever experienced here within my listening room. Absolutely beautiful, remarkable sound!

Specifications
Type: Mono vacuum tube amplifier
Frequency Response: 10 Hz to 60 kHz
Power: 30 Watts for AA62B or 35 Watts for AA82B
Input impedance: 47 kOhms
Class Of Operation: SE Triode Class A
Output Tube Complement: AA62B or AA82B
Load Impedance: 4 or 8 Ohms
Negative Feedback: 0 dB
SNR: 92 dB
Input Sensitivity (@ full power): 600 mV
Inputs: Unbalanced RCA and balanced XLR
Dimensions: 320 x 600 x 250 mm (WxDxH)
Weight: 88 lbs. each monoblock amplifier 
Price: €22,500 / pair with AA62B, €25,000 / pair with AA82B

Company Information
Ayon Audio
Hart 18
A-8101 Gratkorn
Austria

Voice: +43 3124 24954
Fax: +43 3124 24955
E-mail: ayon@ayonaudio.com
Website: www.AyonAudio.com

United States Distributor
Ayon Audio USA
8390 E. Via De Ventura
F110-194
Scottsdale, AZ 85258

Voice: (888) 593-8477
E-mail: sales@ayonaudiousa.com
Web: www.AyonAudioUSA.com