Review
text by WOJCIECH PACUŁA
translation Marek Dyba
images by „High Fidelity”
No 253
June 1, 2025
⌈ When, in 1986, Messrs. ATSUSHI MIURA and MASAMI ISHIGURO founded A&M Limited, which owns the Air Tight brand, they never suspected that thirty-nine years later their company would still be producing worldwide award-winning top-of-the-line tube gear. And so it is. We are testing the latest version of the ATM-1 power amplifier in the 2024 Edition, or ATM-1E for short. ⌋
AMONG THE MANY DIFFERENT PRODUCTS FROM JAPAN, those with the Air Tight logo seem to me to be the essence of marrying design thinking to the broader perspective and the closer one. The broad is about skillfully balancing the lineup, including the design of the products for the audio market. In such a way that they do not get locked into the narrow idiom of super-purists denying any compromise we arbitrarily point out, which one faces every step of the way in audio. But on the other hand, the closer one, of being aware of the importance of the issues they raise, giving them enough priority in the designs not to lose sight of what is most important - the sound.
I got a little technocratic, and the point is simply that Air Tight's amplifiers are both well-designed mechanically and design-wise, and have everything you could ask of a small, specialized company. Such as the fact that this company's products are small. Or at least smaller than most of the competition. This allows for better vibration control and a shorter signal path. It also helps reduce material consumption. With this in mind, let's look at its latest product, the ATM-1E stereo power amplifier, from this angle.
▌ ATM-1E
The tested amplifier is a tube-based, stereo power amplifier with a solid-state power supply. The signal to it must come either from a preamplifier or from an adjustable output of a signal source, such as a CD, SACD, file player or phono preamplifier with an attenuator in the output.
This is another version of a device that has remained in the range since its inception, since 1986; it was simply the ATM-1 model. The new version, ATM-1E, where E stands for “Edition”, ATM-1 2024 Edition debuted at the Munich High End Show 2024, replacing the ATM-1S model. As I said, the device is small. Its weight, however, exceeds that found in many times larger devices. With dimensions of 365 x 305 x 225 mm (W x H x D), it weighs as much as 21.5 kilograms. So all the weight is concentrated on an area only slightly larger than an A4 sheet of paper (A4 = 210 x 297 mm).
I mentioned that the amplifier with its small size helps to dampen vibrations. The manufacturer pays close attention to it. Indeed, in the press materials it reports that the chassis is a “monocoque” design. The idea here is that it is a sort of thin “shell” to which all other components, such as transformers, manipulators, feet, etc., are attached. But you should know that the sockets for the tubes are embedded in a separate copper plate suspended from the top panel; the bottom panel, enclosing the whole system, is also made of copper. Let's add that the circuitry is assembled using a point-to-point assembly technique without a circuit board. An expensive technique, but one that shortens the signal path.
The amplifier offers 35 watts per channel, at 5% distortion, achieved with EL34 tubes operating in a push-pull, Class AB circuit. These tubes are driven by dual 6CG7 (6FQ7) triodes, which are also phase inverters. In the input, we find a 12AT7 (ECC81) dual triode, common to both channels. All tubes bear Air Tight logos and are selected and paired by that company. Underneath, however, is the gray Electro-Harmonics logo. Their manufacturer is (unfortunately) the Russian company New Sensor (Sovtek, Svetlana, Electro-Harmonix, Genalex Gold Lion).
The amplifier is finished with the company's classic colors, that is, a steel front, transformer and choke covers of a slightly different hue, and a black chassis that shimmers in the light. It's made of 1.6 mm thick steel plate, and the paints were “borrowed” from the automotive market. On the front, there are silver metal-milled knobs, that allow user to set the input sensitivity. The latter, with them in the maximum position, is 700 mV, so it is quite high. They are separate for the left and right channels and are not synchronized. Nevertheless, there are those who treat the ATM-1E as a complete integrated amplifier due to this functionality.
The third knob is used to activate the VA meter located on the top panel. The latter is not round, but oblong, and resembles the gauges used in the 1970s. There are four potentiometers correlated with it, the axes of which can be found on the top panel. You can use them to set perfectly the same bias for all output tubes. And there is also a power switch; the unit features no standby mode. On the back there are two sets of gold-plated speaker sockets, for 4 and 8 ohm taps. You can also order a version with a 16 Ω output. Line inputs are single-ended - these are Amphenol's rugged RCA jacks, typically used in professional equipment, as their housing is the size of XLR sockets.
As we learn from Ken Micaleff's review of this unit for Stereophile magazine, the new amplifier doesn't have much in common with the ATM-1S version, much less the original ATM-1. As Mr. Yutaka “Jack” Miura, managing director of A&M Limited and son of the late founder, Mr. Atsusha Miura, told him, the biggest difference is the way the amplifiers were designed. We learn that the ATM-1S was prepared in 2006 by the old design team, while the ATM-1E was created between 2022 and 2024 and its designers were part of a new team. They were Mr. Yoshihiro Hayashiguchi (product designer) and Mr. Kiyoshi Hamada (circuit designer), responsible for all Air Tight products since 2015 (more → HERE).
The components used to build the new amplifier are also different. In the ATM-1S, the output transformers came from Hashimoto, while in the ATM-1E these are Tamura transformers, as is the choke used in the power supply. Both amplifiers use EL34 pentodes in the output, but the older version used one 12AX7 and two 12AU7 tubes in the input; in the ATM-1E you'll find one 12AT7 (for voltage gain) and two 6CG7s (in the amplifier control and phase inverter). Nice passive components were used, from AuriCap, Mundorf, TE Connectivity, Cornel, United Chemi-Con, Unicon, TDK and KOA.
The device is small, but there is power in its body or shape - I like it very much.
▌ SOUND
HOW WE LISTENED • The Air Tight ATM-1E was compared to my reference amplifier, the Soulution 710 solid-state power amplifier, and drove Harbeth M40.1 speakers. Preamplification was handled by an Ayon Audio Spheris III tube preamplifier. Separately, I also listened to a Leben CS-600X amplifier based on EL34 tubes.
The signal between the preamplifier and power amplifiers in both cases was carried by Crystal Cable Absolute Dream interconnect. The tested amplifier was powered by Harmonix X-DC350M2R Improved-Version cable, and the signal to the speakers was provided by Crystal Cable Da Vinci speaker cable (more → HERE ˻PL˺). The signal source was an Ayon Audio CD-35 HF Edition SACD player.
RECORDINGS USED FOR THE TEST ⸜ a selection
⸜ CHET BAKER, Baker’s Holiday, Verve Records B0003279-16/SUHD 009960, Test Press SACD ⸜ 1965/2004.
⸜ TOTO, Toto IV, Columbia/Sony Music Labels SICP 10139~40 „Deluxe Edition. 40th Anniversary”, SACD/CD ⸜ 1982/2022, reviewed → HERE.
⸜ GEORGE MICHAEL, Older, Epic | Aegean/Sony Music Labels SICP-31544-5, 2 x Blu-Spec CD2 (1996/2022) ⸜ reviewed → HERE.
⸜ AKIRA TANA TRIO, A New Picture I, ShinRec SRCD-8030, CD ⸜ 2024.
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EVERY TIME I listen to a well-designed, lovingly crafted amplifier working with EL34 tubes I am reminded why these are my favorite power tubes. Warmth, fullness, density, saturation - these are the things I look for in music reproduced at home, and what I really often get with this type of amplifier. And it doesn't matter what price level we're talking about. The devices may differ in the way they realize particular characteristics, but the overall vision remains the same.
The ATM-1E is one of the best amplifiers of its type that I know. CHET BAKER's vocals from the Baker's Holiday album were remarkably smooth and silky with it. And warm. And big. And palpable. So was the trumpet entering at around 2:18, in the ˻ 2 ˺ Easy Leaving. It's a muffled trumpet, but beautiful in its depth and fullness. The Japanese amplifier showed all these details momentarily. So did the piano and guitar subbing in the right channel. It was warm yet clean playing.
The purity I heard was part of the differentiation. The tested amplifier is unique in this respect, that is, when it comes to the ability to combine these two elements. Actually opposite ones, because when we push for a dark tone, we tend to lose sight of the whole. Here the vocals were in the foreground, followed by the accompanying instruments behind and to the sides, but further away. These elements differ strongly in timbre, as - for example - in ˻ 2 ˺ You’ll My Thrill, and are usually likened to each other. Not so here.
As we wrote, the ATM-1E is a version prepared by Air Tight's new team - new by Japanese standards. Their hand can be heard in much better resolution and, consequently, clarity. Previous versions of this amplifier, as well as the ATM-2 series amplifiers, were more strongly focused on immersion into the sound, letting go a bit of the spatial relationships between instruments, as well as differentiating them from each other in terms of timbre. “E” goes ‘wider’, more strongly in terms of recognizing the sound.
And deeper, I might add. This is an amplifier playing really low. When the bass hits at the beginning in ˻ 10 ˺ Africa, the closing track of the TOTO's fourth album, it hits hard and thick with the ATM-1E. Moments earlier I listened to Baker at a really high volume level and it didn't make a special impression on the amplifier. And even if it did, it went into overdrive gently enough so that it was impossible to pinpoint the exact moment when it happened.
Once again I heard, what with the Baker's Holiday album might have seemed natural, that is, the excellent differentiation of space and color of vocals and instruments. While there it is inherent in the production of the recordings, because the voice was the most important element, it is not so clear in the production of the Toto album. Air Tight, however, played it as if it were a largely purist recording. The vocals of the band members, recall that as many as four members serve as “lead vocalists,” were clearly placed before the instruments. And when the producers blended them into the instrumentation, although their three-dimensionality disappeared, they were still clearly cut off from the other sound sources.
Listening to this CD, I couldn't help but notice that the Japanese amplifier does something at the turn of the bass and midrange that makes the sound very “lively”. Usually companies try to achieve such effects by brightening the upper midrange and opening up the top end. Here it is different. It seems that the range from around 200-400 Hz is boosted and it is responsible for “invigorating” the sound. It has a stronger saturation and “elevates” the sound sources higher in their energy. It's as if they get something like a boost, like a cyclist switching to a higher gear in his electric machine.
I don't see this as a departure from tonal neutrality, as it's subtle in terms of timbre. It is, however, crucial to building that presentation. That's why first Chet Baker, then Toto, and now, as I write this, GEORGE MICHAEL from the Older on the Blu-Spec CD2 released in Japan in 2022, virtually all the CDs I listened to with the Air Tight sounded authoritative, powerful and dense. But also in a differentiating way. This is probably the thing Yutaka “Jack” Miura was referring to in the Stereophile magazine review cited above, when he talked about a “common line” for all of the company's devices created after 2015.
This is, in my opinion, the right line, the right direction. Not because it breaks with what it was, it's not about that. I could live with every amplifier from this company I've tested in the last twenty years, including before the design team change. But once heard, the ATM-1E shows that by building on something that came before, one can go further in extracting emotion from recordings, in showing their complex structure, not just in gutsy, purist productions, but with any, as long as it's good, music.
| Our albums
⸜ CHET BAKER IN PARIS SACD COLLECTION
Chet Baker Quartet, Berclay Disques/Universal Classics & Jazz UCGU-9074 ⸜ 1955
Chet Baker Quartet. Vol. 2, Berclay Disques/Universal Classics & Jazz UCGU-9075 ⸜ 1956
Chet Baker And His Quintet With Bobby Jaspar, Berclay Disques/Universal Classics & Jazz UCGU-9076 ⸜ 1956
SHM-SACD ⸜ 1955-56/2024)
CHESNEY HENRY BAKER Jr., who bore the stage name CHET BAKER, was an American jazz trumpeter and singer. Wikipedia briefly summarizes his remarkable life, writing that he was one of the most important musicians performing, so-called, cool jazz, working with Stan Getz, Charlie Parker and Dexter Gordon, and further that he gained fame playing in Gerry Mulligan's quartet. From 1954 he began performing with his bands, and from 1957 also as a soloist. From 1954 he also sang. He died tragically in Amsterdam, in 1988, falling out of a hotel window; the story was immortalized by Bruce Weber in his film Let's Get Lost (1989).
What is important for this story is that the musician had a long, and mutually rewarding, relationship with Europe. Recall that he played on this side of the Atlantic many times, and in the 1970s, until his death, he also lived here. His flirtation with the Old Continent, however, began two decades earlier. In 1955, Baker gave a series of concerts in Paris, which, it is said, “went down in the memory of jazz scholars and created a unique relationship with the French public.” It was from this time that the three CDs come, originally prepared by the French publisher, Berclay Disques: Chet Baker Quartet, Chet Baker Quartet. Vol. 2 and Chet Baker And His Quintet With Bobby Jaspar; Berclay Disques today belongs to Decca France.
Released in 1955 (the first) and 1956 (the other two), the albums come from sessions that took place in a short period of time. The first took place on Monday, October 24th 1955, between 2pm and 9pm at the Pathe-Maggellan Studio in Paris. At the time, only Jimmy Bond remained in Chet's band: Peter Littman returned to America, and was replaced by Nils-Bertil “Bert” Dahlander, a Swedish drummer who had previously accompanied Lars Gullin. The almost unknown pianist Gérard Gustin, with whom Eddie Barclay, founder of the Berclay Disques record label, had just signed a contract, played the piano.
According to the publisher, “the circumstances forced the band to return to standards that Chet could play better than anyone else.” He chose eight titles, including These Foolish Things, which remained in the quartet's repertoire for a while, five others that the trumpeter played here for the first time, and two others that less than ten days earlier he had played with Lars Gullin and Dick Twardzik, whose disappearance Chet still refused to accept. As we read further, “the entire session exudes a certain sadness that cannot be hidden, regardless of the tone or tempo.”
Vol. 2 of the Chet Baker Quartet was recorded over two days, October 11th and 14th 1955, also at Studio Pathé Magellan in Paris. In contrast, the last disc, which also features the name of saxophonist and flutist Bobby Jaspar, includes a material from several different sessions recorded between October 25th 1955 and February 1st 1956. Despite the title, only one session (December 26th) shows Jaspar on tenor sax, performing How About You? and Chik-Eta. The other sessions show Baker leading groups of varying composition: quartet, quintet or octet.
These albums were reissued on LPs some time ago. On September 24th 2024, the Japanese division of Universal Music released these three titles on SHM-SACD (Super High Material Super Audio Compact Disc). These are discs made using the SHM technique, that is, with a different material instead of polycarbonate, and with a single SACD layer, without a CD layer. The material for them was ripped from “master” tapes and remastered using DSD technology. The discs were released to celebrate Chet Baker's 95th birthday, which was in 2024.
It is widely believed that the benchmark for 1950s jazz recordings are those from the US, most notably Roy DuNann’s and Rudy Van Gelder’s. This is true. Their European counterparts from that time are not technically as perfect. However, if we temper our expectations of the “extraordinary,” we find that we get a very believable and extremely natural rendition. Baker's monophonic recordings are a good example of this.
Their sound is warm, low and dense. The trumpet is always in the foreground, and has a clear “presence”. Despite this, it is not intrusive. I would even say that it sounds quite warm. You can also hear the drums really well, which, although placed behind the trumpet, is much more open on the top end than it. Especially on the first disc. It also has clear textures, which is not at all common in jazz recordings from that time. At the beginning of Vol. 2 it was shown in a slightly more muffled way, but by the second track it is clearer.
The trumpet on the second disc is also a bit more muffled. But here, too, it has an excellent “presence” through the large volume. But, in general, the second disc brings a worse sound than the first. And the third disc is even different. Less saturated, more open in the midrange, with less saturated double bass, and is less resolving. The drums are farther back in the stage here, and the trumpet is not at arm's length. Whatever one may say, however, all three are excellent playing and very pleasant sounding. ●
→ www.UNIVERSAL-MUSIC.co.jp
TALKING ABOUT THE RECORDINGS that give us exceptional sound quality, it must be said that - ultimately - the Air Tight ATM-1E is a warm sounding amplifier. In the sense that the treble is dense with it, it has weight and sonority, it also has high energy. However, since the low midrange is most important here, our attention shifts lower, as with the piano in the recordings from the AKIRA TANA TRIO A New Picture I. This is an incredible recording, made at 100% with just two microphones, and with an energy that surpasses most of what is recorded in a classical microphone arrangement.
And it was with her that this privileging of a part of the band, but not so much in color, but in the way of building a strong body, was shown early on. I'm talking about ˻ 1 ˺ New Picture, a piece by Jimmy Heath, when the leader's piano momentarily caught my attention with a deep sound usually lost in recordings made for two microphones. The double bass solo played a moment later showed something else. The tested amplifier perfectly differentiates space and the relationships within it that occur between instruments.
And then there's that treble! - I've written before about warming of the sound, but when something plays like it did at the end of the sixth minute of the aforementioned track, with energy, passion and power, it sounds great. In truth, it sounded as if from a good 300B tube, but with better lower end fill. And still with higher energy given in the attack of large sound elements, not only in the form of the “slam” of the snare, but also in the emphasis caused by the finger hitting on the double bass string.
PREAMPLIFIER • Finally, I tried an option that begged to be tried, although reason tells me that it is only an option, not the main function - listening without a preamp, using potentiometers at the input of the power amplifier.
This is not a bad solution, In the sense that, given the need to spend at least the same amount on an external preamplifier as on the power amplifier itself, the sound without it will be very good. It will differ in having a stronger opening in the top end than in a system with the Ayon Audio Spheris III preamplifier. In fact, it was the same when I listened to music using the volume control on the Ayon CD-35 HF Edition player. The changes in question are clear, and it's not that getting rid of the preamp improves the sound, that's completely wrong.
Without the Ayon Spheris III in the track, the sound was less differentiated within bodies and timbres. The overall sound was also closer to me, while at the same time the back of the soundstage was less illuminated, more hazy. The energy was high, the slam was immediate, and the attack of the drum beats was sonorous and even “snappy.” But the overall sound was also no longer as enchanting, as engaging, as before. Therefore, playing music without a preamplifier will be the way out for those who want to buy one in the future, and in the meantime already want to enjoy the advantages of this beautiful power amplifier - advantages most of which you will get whether you play music with or without a preamplifier.
▌ Summary
THE DIRECTION THAT AIR TIGHT took in 2015, when a new design team started working for it, seem to hit the spot. The gentlemen did not discard what had been previously developed by the company, but took it, looked at it and proposed changes that pushed the whole thing forward. That is, in the direction of greater resolution and clarity, because that seems to be what this is all about.
So in the sound of the ATM-1E you will find energy, on the one hand, and attention to detail on the other. This is an amplifier playing warm and low. Despite its relatively low power, it can drive even difficult speakers, as long as you don't make it do it in a large room. It enters into overdrive gently, so it doesn't harden the sound, even at high levels. Well, and it looks great, which is - at least for me - as important as the sound. ●
▌ Technical specifications (according to the manufacturer):
Tubes:1 x 12AT7 (ECC81), 2 x 6CG7 (6FQ7), 4 x EL34
Nominal output: 2 x 35 W (1 kHz/THD
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THIS TEST HAS BEEN DESIGNED ACCORDING TO THE GUIDELINES adopted by the Association of International Audiophile Publications, an international audio press association concerned with ethical and professional standards in our industry, of which HIGH FIDELITY is a founding member. More about the association and its constituent titles → HERE.
→ www.AIAP-online.org
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