⌈ AUDIO REVEAL is a brand that was set up in 2016 on the initiative of Mr Michał Posiewka. He has been manufacturing equipment since 1989, but he initially produced alarm systems. Audio Reveal is the outcome of his audiophile passion. We are testing the second amplifier offered by the company – a model called the SECOND. ⌋

There is something extremely attractive in the simplicity of single-ended tube amplifiers, i.e. ones with class-A output tubes amplifying the whole signal, without dividing it into a positive and negative half (like in push-pull amps). If we look at their circuit diagram representations, we will come to the conclusion that things cannot be any simpler. There is a resistor, an input tube with an attenuator in front of it, a capacitor or a transformer coupling the output tube, the output tube itself, an output transformer – and that’s it.

However, one of the basic rules in the audio domain is that when the number of components in an audio circuit is minimized, the signal path is simplified. On the other hand, errors that cannot be ignored in electronics are not corrected in such a case. To cut a long story short, the simpler a circuit is, the more clearly we hear all errors and distortions. And an SE circuit – one with triodes or pentodes (and beam tetrodes) on the output is an extremely simple circuit.

A solution to this problem is a circuit designed and made in such a way that distortion is minimized. Combining these elements in the best way possible allows us to distinguish between craftsmanship and art. As for single-ended amps, this means a lot of investment, extensive know-how and long listening sessions.

| SECOND

Mr MICHAŁ POSIEWKA, a constructor and the owner of AUDIO REVEAL, a small “boutique” company from Warsaw, does not seem to be discouraged by these problems. His company now offers two integrated amplifiers, both based on the “single-ended” concept: the FIRST model that we tested in January last year and the SECOND model presented for the first time during the Audio Video Show exhibition. The company is now preparing a third amplifier to become the basic model offered by the company.

MICHAŁ POSIEWKA
Owner, constructor

WOJCIECH PACUŁA: Where does the name, Audio Reveal, come from?
MICHAŁ POSIEWKA: On the one hand, we wanted to make it different from other existing brand names. It is not so easy to find an interesting name. However, we also wanted it to inspire our clients. The name was invented by my son. It refers to discovering new things in music.

WP: The Audio Reveal brand was set up in 2016, but you had work in the field of electronics before, hadn’t you?
MP: Yes, I’ve been running my company since 1989. We will be celebrating our 31st anniversary on August 1st this year.

WP: You are also an audiophile…
MP: That’s correct. I’ve been an audiophile for about 18 years. I started with Mission loudspeakers and then there was NAD with Focal loudspeakers, i.e. transistors. I started using tube devices later and my first encounter with them was actually a hybrid solution – an amplifier from the Italian company Unison Research. The next one was another Unison Research model, this time a tube one (push-pull), based on EL34 tubes. And then I developed a prototype of my own amp and registered my brand name. This is how the First model was created.

WP: Why did you choose the KT88 tube?
MP: I initially tried to create a single-ended amp on EL34 tubes and that was the pre-prototype of the First model. We also wanted to have one tube in the preamp. However, it appeared that it was not exactly something that I liked. That is why I chose the KT88. However, this is not everything. While introducing my first amp model, I wanted people not to have problems with driving their loudspeakers. One can obtain 10 W from a single KT88 tube, which is not much, and even less from the EL34.

I could have used two parallel tubes, but, again, that would have increased the cost. I did not want my amplifier to be very expensive. In the end, I decided that the KT88 tube fulfils my requirements, but it was necessary to use two such tubes in the amp, as it is a tube that requires effective driving. So, it would be worth being able to offer a yet cheaper amp and this is something we will have achieved sooner or later. We will need to select more sensitive loudspeaker for the purpose, but I suppose it is only natural.

WP: How about the Second with the KT150? Did you want more power?
MP: Yes, we wanted to be able to drive more “problematic” loudspeakers. However, I can say that the First is doing really well and it is going to be sufficient in most cases. I specify the power offered by my amps in a very conservative, “safe” manner – 10 W for the First and 20 W for the Second, but it is much less that they can give you. Actually, manufacturers do not give real power values – I can say this, having measured a few dozen various models. Everyone defines them as being higher, often raising the real value by even 50%.

This is a machine used to manufacture the wooden fronts of Audio Reveal amplifiers

While constructing my first amp, I imagined that the people who choose a tube design for their systems know everything about the tube. In reality, however, they are only learning everything. That is why it is easy for companies to manipulate data, as it is not only power itself that matters, but also the way you measure it. And here it is possible to abuse information. That is why I try to give the lowest power values possible to obtain from my amps and not the highest ones – people who buy audio gear deserve to be treated fair.

WP: How does your single-ended design differ from other designs of this type?
MP: I think that the quality of craftsmanship and reliability of operation are the two main features that make my amplifiers different in all respects: from the professionally made packaging to finish details. It is obvious that the most important thing for an amplifier is to produce good sound, but it also needs to be excellently made. Creating such a device is not easy and everyone who has ever tried to enter this industry knows that.

The Second is similar to the First model, but it is a dual mono design. I have also used Hammond driver transformers. I wanted all the components to be the best, as one can hear everything with such a simple circuit. I wait for a long time for the tubes, as I order batches with specific parameters, which means they first need to be measured and selected. The differences in the parameters of currently manufactured tubes are enormous, much bigger than in NOS tubes. It is all time-consuming and much more expensive, but it’s worth it. ♦

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The size of the tested amp is not impressive, but it takes two people to lift and carry it. You can try to carry it on your own, but it is not easy to find a good spine specialist these days and subsequent rehabilitation is more difficult to perform, so I advise you not to do it. Over 33 kg of weight is a serious burden – the enormous class-A Accuphase E-800 (200 W into 2 Ω) weighs only 3 kg more!

Transformers| The weight of the device mainly results from the transformers and cabinet used. The former are much bigger than required by the design, but the constructor thinks that IT should be a norm.

It is a dual-mono design with separate power transformers, so there are four large transformers made using a 0.3 mm EI annealing formers, additionally screened with a copper sheet, enclosed within thick steel screening cans. After milling, small brass plates with engraved transformer symbols were place on their tops. The power transformers were manufactured by Mr Ogonowski’s Polish company, while the output ones have come to Poland from the Canadian Hammond company.

Cabinet | The cabinet has been made using 2 mm-thick steel sheets in order to maintain mechanical integrity, which is not easy to achieve considering the weight of the components. However, the front panel is made from Merbau wood. Stainless steel sleeves that match the knobs used are combined with it. All these elements are excellently made and they match one another.

We use the largest knob placed in the center to control the volume. There is a small round window to its right and I initially thought it was a headphone output, but it is an infrared receiver. We also get a small metal remote control with the amp, including two buttons: volume up/volume down. On the right there is an input-switching knob (there are four inputs) and on the left – a supply voltage switch coupled with a LED. After power is turned on, the LED flashes, while after supply voltage stabilizes, it emits constant green light.

Components| The manufacturer pays attention to using high-quality components. Apart from expensive transformers, there are Mundorf Supreme capacitors placed in the signal path, polypropylene Wima and electrolytic Nichicon capacitors, Vishay, Arcol and Ohmite resistors, and transmitters made by the Japanese Takamisawa company. The RCA sockets are made of gold-plated brass, while the signal pin – from copper mixed with tellurium. Cables in the signal path are made from oxygen-free copper. Solid aluminum was used to manufacture the feet fitted with rubber O-rings.

Accessories| The amp offers us the possibility to choose between two feedback levels (8 dB and 11 dB), using a small knob on the top panel. There are four line inputs, but there is no line output (e.g. one designed for an external headphone amplifier). There is no built-in phono stage or (which is even more obvious) DAC/Bluetooth receiver, either. It is a pure amp. However, we do get double speaker outputs from transformer taps at 4 and 8 Ω. Let me also remind you of the remote control again.

Design| The amp makes a very good impression. It is robust, has good proportions and comes across as being really “pro”, but also affordable. The amp kind of resembles devices manufactured by the Italian Unison Research company – what I mean is the combination of wood at the front, the black cabinet, steel inserts and metal plates bearing the tube symbols on the top panel.

Tubes| This is the last component I am going to talk about, as I did not want it to “shade” everything that I have written so far. That is what might have happened, as the tubes are really interesting. There is a double 12AX7 (ECC83) triode on the input, operating in the preamp section (it was manufactured by the Tung-Sol company). Signal is then sent to the driving tube, i.e. the much bigger double 12BH7AEH triode with gold-plated feet, made by the Electro-Harmonix company. It is interesting that it is used so rarely.

Only triodes are used here for amplification, except for the power tubes – these are the beam KT150 tetrodes. It is the latest model from the KT series, so far available in the offer of only one manufacturer – the Russian Tung-Sol company. At the moment, the Czech KR Audio Electronics company is also offering its own, much more expensive version (a single tube costs ca. €400). We have known the KT150 from a few excellent amps, e.g. the Ayon Audio Spirit V, but it is almost always found in push-pull designs. Here it operates in class A, in a single-ended design, just like the rest of the components.

| THE WAY WE LISTENED

The Audio Reveal SECOND amp was placed on the upper shelf of the Pagode Edition rack, next to the Ayon Audio CD-35 HF Edition player, i.e. where the FIRST model also stood once. Signal was sent between the devices using the Crystal Cable Absolute Dream interconnect. The tested amp drove the Harbeth M40.1 loudspeakers that are not an easy load to deal with. The Audio Reveal amp has a very big PSU with two transformers and really high output power for a single-ended design, so it drove the Harbeth speakers without any difficulty. The amp and the loudspeakers were connected in an unusual way, using NOS Western Electric WE16GA cables.

There are a few things from outside the domain of music that are very important in this design. The most significant one, as I believe, is very quiet operation of the device. What I mean is that we hear virtually no mains hum. However, if there is any, you need to place your ear close to a large speaker and stop breathing, and then you might, perhaps, hear something. Secondly, the amp produces much less hum than other tube amplifiers. When it comes to tubes, both of the elements that I have mentioned are a compromise between technical requirements and the capabilities of the tubes themselves. Here, both are just excellent.

The lack (or a low level rather than a complete lack) of distortion so characteristic for tube amplifiers results in excellent sound differentiation in the tested amp. Top-bottom, front-back, left-right – everything is clear and unambiguous, like in Pink Floyd’s Welcome to the Machine from the album Wish You Were Here, with a very nicely shown machine “pulse” and sonorous, but not warmed up guitar strings on top of the mix, with the pick being moved from the bottom to the top.

What I am talking about could be heard even more clearly in terms of the vocal. For most of the time, we have lyrics in the foreground, strongly sang with effort, from the throat, but there is a low “reflection” beneath (almost a melodeclamation). It is similar to what Peter Gabriel did in the song Mercy Street from the album So. The Second model showed this really faithfully, but also in an exceptionally musical manner, as it is a device that effortlessly and without any problems combines both of the aspects of music reproduction.

It is because it is not yet another stereotypical tube amplifier. If you are only looking for warmth and your goal is total relaxation, you will not necessarily find it with the Audio Reveal amp. There are other, also excellent amplifiers that will provide you with that – and they are not necessarily tube devices. The tested amp is different. It offers an exceptionally precise and therefore not rounded sound attack, and, consequently, it does not warm up the musical message.

It is beautifully illustrated by the Midnight Sugar album of the Yamamoto Tsuyoshi Trio! It is one of the most excellently recorded jazz piano performances, due to the fact that the sound attack is wonderfully captured, but with a fill that comes right afterwards. It sounds glassy in brightened-up systems and only thanks to high-quality gear, loudspeakers and cables it appears simply dynamic and sonorous, while the glassy character results from poor resolution.

That is why we do not get “warmth” with this amplifier, but rather a strike, momentum, fill and a wide frequency range. The Audio Reveal amp sounds “broad” – both when it comes to dynamics, space and the frequency response. It does not go very low in terms of bass, but we do not hear it like we do with transistor amplifiers. The upper and mid-bass are a little contoured, clear and selective, thanks to which everything gains momentum and becomes “meaty”. And it does not matter whether it was a jazz trio or, right afterwards, Pink Floyd’s What Do You Want From Me, as it was always dynamic, full-range sound.

However, we choose tube and not transistor designs for a reason (I am talking to those who are going in this direction), don’t we? That is why, fortunately, the Audio Reveal amp does not imitate a transistor device. Its harmonic structure is deeper and better differentiated than in most transistor amplifiers from this price range. Despite this, the sound is sonorous, as well as internally aligned. This is sound that reaches us instantly in its full, without getting divided into individual elements.

So, the albums that we love both for their music and recording quality, will sound great with the amp, sometimes even brilliant. It was so with the record from the Three Blind Mice record label and with Patricia’s Barber Cafè Blue gold HDCD edition from the First Impression Music record label. However, it is not the case that other records won’t sound good with it. To tell you the truth, what I was talking about (i.e. a combination of neutrality with naturalness) is even more clearly audible with the records that we do not listen to be delighted by their sound, but for the music itself.

It was so with Faith by The Cure, recorded in 1981. It is a classic example of sound called “new wave” in Poland, often associated with gothic rock. I bought it at an exhibition in Prague – it is the first CD edition of the album (have a look at what I have already written about Compact Disc album editions in an article titled: The Autumn Of Compact Disc). During the exhibition, I also chose an album by Robert Fripp, released by Nimbus Records, but before I came back with the money, someone had already bought it…

Anyway, The Cure album sounded cool, with quite high balance, but it did sound as it should, without being brightened up and losing the characteristic sound. Simon Gallup’s bass was also wonderful, clear, selective and nice. Perhaps it lacked the lowest range, but that is how music was recorded at that time. Smith’s vocal was situated quite far away in space (and in the mix), but it did not merge with the background, which confirmed very good differentiation offered by the tested amp again.

‘F’ for ‘feedback’| The fact that a tube amplifier has been equipped with a switch that one can pick negative feedback depth is nothing new. However, it is weird, in my opinion, that this function is not available with all amps. It is because it allows to match the operation of an amp to specific loudspeakers (more about NF in a review of Audiopax Maggiore m50 power amp review).

When it comes to the Second, it was all clear straight away – the only sensible setting was one with the letter ‘F’ on top. During the test, I did not know which of the settings meant deeper and which more shallow feedback – it was a blind test. The secret is revealed by the need to turn the volume up (I did it in my player) by 3 dB when the ‘F’ knob is turned to the side.

The sound would become denser then, while the bass was a little shorter and more disciplined. However, the space and freedom of sound were gone. It was not the same energetic sound as before. That is why the whole listening session was conducted with the letter ‘F’ on top. You may obviously have a different opinion – everything depends on, as I am saying, the synergy between the amp and the loudspeakers.

| CONCLUSIONS

As you can see, the set of features that the Second is characterized by does not fit the ‘tube amplifier’ scheme. On the other hand, it is neither sound typical for a ‘transistor amplifier’, but colorful sound with a momentum and a full range. It is internally complex and wonderfully differentiated. The amp will effortlessly deal with even difficult loudspeakers, which is good information for those who are suspicious of single-ended amps because of their low power. The problem does not occur here.

And we do get something that is only possible to obtain with tube amplifiers or the most expensive transistor amps. It is something that can be called ‘fidelity’. We listen to subsequent albums and believe that we get the sound the way we should, even if our common sense tells us that that there are more expensive and better amps that show even more. While using the Audio Reveal amp, we get a similar impression of “accuracy” and “fidelity”. It is simply a “high fidelity” amp…

Let’s combine it with some good loudspeakers, but not brighten it up with any element in the system and we will obtain open, fast, dynamic, but also internally complex sound that we can bring into very expensive systems owned by our friends and acquaintances. I guarantee you will see them smile in disbelief. Yes, the Second is so good! ■

Technical specifications (according to the manufacturer)

Driving tubes:
2 x 12AX7 (ECC83) | 2 x 12BH7 (ECC82)
Power tubes: 2 x KT150
Frequency response: 20 Hz – 25 kHz (±0.6 dB/1 W)
Rated output power (1kHz): 20 W RMS/4 Ω
Line inputs: 4 x RCA
Input impedance: 50 kΩ
Start-up time: 60 s
Rated power consumption: 240 W
Dimensions (W x H x D): 476 x 410 x 220 mm
Weight: 33.1 kg