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Amp/Preamp Asylum: REVIEW: Air Tight ATM 3 (mono) Amplifier (Tube) by davehg

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REVIEW: Air Tight ATM 3 (mono) Amplifier (Tube)

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Model: ATM 3 (mono)
Category: Amplifier (Tube)
Suggested Retail Price: $15,000
Description: EL34 mono block amplifier 55wpc triode/110wpc ultralinear
Manufacturer URL: Air Tight
Model Picture: View

Review by davehg on October 21, 2008 at 22:58:48
IP Address: 71.231.191.35
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for the ATM 3 (mono)


I've loved Air Tight gear ever since I was a college kid selling hifi to make ends meet. The ATM 1 and ATM 2 are classics, and the newer (by Air Tight standards) ATM300 and ATM 211's are truly beautiful to see and hear. But the sweetest amp Air Tight has made is the relatively rare ATM 3 monoblocks. After a decade of wanting a pair, I finally managed to locate a pair of the later model ATM 3's (these have the detachable power cord). Mine have been upgraded by Air Tight service tech and master guru Tom Tutay, well known in Air Tight circles. Tom's mods include adding beefier speaker terminals (great for he-man spades) and much upgraded RCA jacks (the originals terminals were weak, easily breakable and a common complaint). Tom also places a tweak that delays the power to tubes on start up, which greatly enhances their life and stability by preventing sudden surge of current on start up. Air Tight's are all hard wired in their innards and the ATM3's have copper cladded internal walls.

If you've ever seen a pair of mint Marantz Model 9's, you have an idea of the ATM 3. Each amp weighs about 70 lbs, and has a gorgeous brushed silver faceplate with a cycloptic eye (the bias meter) in the middle. Six EL34's per side produce 55 watts in triode, and 110 in Ultra Linear. This amp gives up nothing in power except to higher powered VTL's and the like. Bias adjustments are pretty cool: a small rectangle faceplate on the front bearing the logo is removed by two screws, which hide the six bias screws. The screws holding the faceplate do double duty as standard head screwdrivers; simply switch the bias meter to the correct tube and adjust the bias screw until the needle within the meter centered within the correct range. Elegant and simple.

From a bird's eye view, the amp is dominated by two massive transformers, including the acclaimed Tamura output transformer. These are your father's transformers, beefy and solidly constructed. I removed the cages an stored them, since they were held on by several allen screws and it was a hassle to keep moving off and on. Plus I like to see my glowing tubes....

The amp has a large toggle switch toward the rear, which selects triode or ultralinear. I was warned to shut off the amp before switching, as this may produce a large current surge and can blow fuses potentially (it didn't happen the two times I neglected this warning, but I won't tempt fate).

Visually, the amp is elegant. I thought my VAC Avatar SE was a nice piece, but it looks somewhat pedestrian next to the Air Tights.

So how so they sound? Like anything worthwhile in life, they make you wait. About an hour and they relax, and within 2 hours they really become quite much more transparent then when cold. I've heard dealers complain that 6 hours is when they really sound their best.

In Ultralinear, they got much closer to what I consider a classic triode sound than ultralinear, but with excellent bass control and solid dynamics. Meaning, they rocked but not with the typical sparkle that masks a more darker, veiled sound. With my VAC Avatar SE, ultralinear mode meant more power but at the expense of that "you are there" sense you get with with triode. With the Air Tight, the difference between UltraLinear and triode much less apparent. Just a greater sense of solidity, and a slight but noticeable loss of presence. In triode mode, bass didn't get flabby and dynamics were not congested. It just sounded ever so softer, but with noticeable presence and more air.

I got a copy of the original Stereophile review, which suggested triode mode had much more measured distortion and was less desireable (though the reviewer preferred triode mode). I swapped speaker inputs from lower impedance taps to higher ones (which had a clear sonic result on the VAC) but didn't detect anything with the Air Tight.

So, again, how did it sound? Like I remembered when I first heard them: it was like seeing your first real girlfriend, and she looks hotter than you remembered. Very musical, great flow, terrific bass (some of the best I've heard from an EL34 amp). Top end was extended, but dynamics were a little softened compared to other tube amps, especially KT88's. Backgrounds were quiet (not ultra black like the best solid state amps, but free of noise or hum). Notable sonic obvervations included a nice deep stage, and detailed but softer detail on top. Vocals were rich, great body, great but not the best "lit from within" sound (I have yet to find an EL34 amp except the VAC Avatar that has this as good as a SET). Also, great microdetail (though I credit the Calypso preamp for much of this quality).

So what's not to like? The heat, for one. In my little room, 12 EL34's can heat up the room especially in summer. Also, the amp is tube sensitive, and also harder than most on tube life (1500-2000 hours is common). Thank goodness EL34's are cheap, otherwise this might get expensive! Finally, compared to some of the best current high end tube amps like the Lamm, Audio Research, or the newer VTL's, the Air Tight's lack transparency of these newer amps. I am wondering if this last point is tube and system dependent, and I will try to roll a few NOS examples for the input and regulator tubes (12AX7 and 12AU7's). I also wonder whether my current cables are the right match for the Air Tight/Calypso match, and will try to swap out a few other brands.

Oddly, my first impressions were marred by using an Air Tight preamp (ATC3) which I thought would have been a good match. The ATC3 was completely wrong for this system, imparting a glare that could not be cured with tube rolling or cables. It sounded better running my source into the Air Tight and using the attenuators on the amp as volume controls (irksome as this was to setting volume on each track). Inserting the Aesthetix Calypso cured the problem and wrought such a nice sound.


Having heard much of the Air Tight line, I would rank them as follows:

1. ATM3 (Tom Tutay says this is his favorite air tight amp)
2. ATM211
3. ATM 300
4. ATM2
5. ATM1 (nice amp, but underpowered and more classic sound, the ATM3 sounds much better IMHO)


Product Weakness: Tube life could be better, transparency is not quite to the standards of the current Class A rated amps
Product Strengths: Terrific bass, sweet and musical but with detail, incredible build quality, great power and nice dynamics


Associated Equipment for this Review:

Amplifier: Air Tight ATM3
Preamplifier (or None if Integrated): Aesthetix Calypso
Sources (CDP/Turntable): Bolder modded SB3 with TriVista 21 DAC
Speakers: Merlin TSM-MMe and Rel Strata III, Devore Super 8
Cables/Interconnects: Acoustic Zen Silver Reference/Hologram II
Music Used (Genre/Selections): rock, pop, folk
Other (Power Conditioner etc.): Foundation Research/Cardas Golden Reference AC cords
Type of Audition/Review: Product Owner




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Topic - REVIEW: Air Tight ATM 3 (mono) Amplifier (Tube) - davehg 22:58:48 10/21/08 ( 7)