Air Tight ATM-1 power amp

Recently Canyon Audio gave me the Air Tight ATM-1 power amplifier for a two week-long test in my home. Here you can read my impression on this nice unit.

The Air Tight electronics are produced by the small “A&M” Japanese company (descendant from Luxman) and the ATM-1 was its first amplifier. Fundamentally, it is a a modern interpretation of the Williamson scheme, using the 6CA7 (EL34) in push-pull configuration to produce about 36W per channel. Other tube complements are a 12AX7 (ECC83) and two 12AU7 (ECC82) as input and differential driver stages, while the two 5AR4 that you can see on the right side are used in parallel to rectify the main power supply. All tubes of this unit come from Electro Harmonix, but are “Platinum Selected” by Air Tight. The aesthetic results simple and compact, despite the about 22 kg of weight.

The ATM-1 is a power amp, but can be used also as an integrate amp. In fact it has also two separate volume potentiometers, that you can see as “sensitivity adjustment” when you are using it as a power amp. It has also a front RCA input, named “CD direct”, that you can switch with the main rear input using the “input selector”. I have used it almost always as power amp, connected to my CJ preamp.

The majority of the ATM-1 weight (and probably of the good sound) is due to its output transformers, which are two big TAMURA SEISAKUSHO, placed just behind the EL34, as to guard those nice tall bottles. The big main transformer seems “small” if compared with the two output transformers, but its power and heat dissipation demonstrate as it is probably well calibrated for this project.

To conclude this short description, I will only add that the output connection are separated for 4 and 8 Ohm. My AZ Adagio are declared at 6 Ohm, but I have measured 5 Ohm an almost all the audio band. For that reason I have chosen the 4 Ohm output.

In the following photos you can see how the ATM-1 compares with my CJ MV55, which also is a push-pull of EL34 (I use the CJ-selected Sovtek or 4 matched Svetlana), but connected in pseudo-triode and has “only” 22W (you barely will need more power in a small room with speakers of 87 dB or more). Comparing the CJ output transformers with the Tamura is just shocking, while the two main power transformers seems of similar proportions. The new CJ MV60 power amp (but probably also the just released LP66) uses better output transformers, derived from the Premier 11 power amp. Probably the best components in my MV55 amp are the polipropilene capacitors, which was a CJ speciality...

My very first impression of how the Air Tight ATM-1 sounds was already close to my final conclusion. The Air Tight is a very good amplifier, in particular for its midrange purity and for the very deep soundstage, but it lacks some “impact” in the bass response. It is not that it has no bass, it simply present a very damped bass response, which does not involve the listener so much as its midrange or its resolution and high frequency details are able to do. Looking for more bass I have tried also the 8 Ohm output and effectively the bass became more filled, but after accurately listening I have found that most of the best performances of this amplifier, like its transient velocity (e.g. Dorati Firebird, Mercury SR90226) were less pronounced in this configuration. So, I went back to the 4 Ohm tap. I don't think that this not-so-full bass is a problem due to limited power. Listening some very challenging records, like the Muti Rite of Spring, MFSL-1-519 (yep, I was finally able to find the original master recording version, wow!) this amp has never lost control, even in the “tutti” big orchestra passages. Something that my CJ can't afford.

For comparison, my CJ MV55 has a more pronounced bass response, but the resolution and “natural midrange” effects were not even comparable with those of the Air Tight. In some way, you can compare the CJ to a cow-boy and the Air Tight to a geisha. It depends of what you need: if you are doing a bear hunt probably you will need a cow-boy, but if you want to relax... then you will probably go with the geisha! I'm feeling that this very damped bass is a “Japanese way to sound”. In fact, very often I saw pictures of small japanese rooms filled with big woofers (JBL, Altec,...) and in that situations you really need a very controlled amp!

The last day which I had the ATM-1 in my system I received -another- Faber visit. Well, I have to admit that also the Air Tight is very sensitive to the cables. Replacing my last Straight Wire Virtuoso Gold signal cable from the CJ pre to the ATM-1 with a new Faber Soft the sound improved substantially (higher resolution, larger soundstage, fast transient). The sound improved even more replacing my Faber Level 1 power cord on the CJ CD player with the prototype of a new Faber top-of-the-line power cord (price around 800 E, but not intended for high power amp): it was able to give the impression of a deeper bass response, even if still very damped. When the ATM-1 departed I and Faber joked with the new power cord connected on the CJ MV55 and its resolution became closer to the ATM-1 one, but without reaching its level of refinement.

In conclusion the ATM-1 is a great amplifier. If you have only two sources you can use it also as integrated and that is a good value, even if joining a good preamp makes the music more clear and elegant. If you listen in majority rock&roll and your loudspeakers are not particularly abundant in the bass region you will better look at other amplifiers. Instead, if you listen more Jazz, Camera and Opera and your speakers/room have already a good bass response you could probably fall in love with the ATM-1 resolution and midrange-to-high natural response.

The official price in Europe is something more than 6000 E, but Canyon Audio is selling this demo unit for 4000 E. If interested, you can contact directly him at canyon.audio@siol.net.