Positive Feedback ISSUE 69
as reviewed by Marshall Nack
The Air Tight ATM-3 monoblocks are very much a tube amp with aspects of the Good Old Days. The design was introduced in 1995 and, true to Air Tight's principles, it is the same today as back then. (Can I equate 1995 with the Good Old Days?) As the importer explained to me, Air Tight only releases finished designs—and one doesn't revise a finished design. They also have more than a touch of the classic tube amp visuals.
I prepared myself for a sonic disruption as I moved the newly arrived ATM-3s into position. My reference is the solid-state Soulution 710 stereo amp, a world-renowned commodity known for cutting-edge speed, resolution and neutrality. In every conceivable way, the ATM-3s come from the other side of the audio world, not least being price: the Soulution 710 is $50,000; the ATM-3s are $21,000.
Thus primed, I had an inkling of what to expect upon engaging the On button, which made a gruff noise when I pushed it, reinforcing the walk down memory lane. Ditto for the hollow ringing tone produced when I wrapped a knuckle on any side of the thin aluminum chassis.
Sure enough, the Good Old Days flooded into the room—top, bottom and mid-range. The treble was oh-so-sweet, of course, and extension was acceptable, but a little more on top would do no harm. The bass was a little warm and loose. The midrange was so full a low-cal diet was in order. If you visualize a continuum with the Good Old Days, or musical, on the left and the measuring-well, or modern sound, on the right, the ATM-3s nudged the needle leftwards.
But, I hasten to add, not too far—these things were not excessive. I was pretty sure that with a bit of minor tweaking and optimization I could get the ATM-3s to deliver top-notch sound. Every component that comes in mandates some re-voicing. For the ATM-3s, it was the usual, plus one addition. Normally, I use walnut wood blocks as cable risers to beef up the midrange. I swapped them out for maple. Next, I removed a couple of Harmonix room tuning dots. Finally, I installed the Dynamic Design Nebula power cord on the Metronome Calypso Transport. All of these adjustments addressed treble extension, bass looseness and the plump middle.
The result proved me right. The needle nudged to the right and landed slightly left of center. The ATM-3s were making fine music. As you'll see, these amps do everything on the audio scorecard well, just not to the nth degree like I get with my Soulution 710. That said, the two presentations differed greatly.
Ever listen to the second movement of Rachmaninov's Symphonic Dances? It's marked Andante con moto (tempo di valse), a moderately paced, waltz-like tempo. I'm enjoying the new recording by Andrew Litton and the Bergen Philharmonic Orchestra (BIS-1751, SACD).
The Air Tight ATM-3 monoblocks set the mood. Brass and woodwinds image well behind the speakers. The solo violin sounds marvelous when it introduces the melody, perhaps a bit rich. Next the oboes enter from center stage and then those swaying violins sing you a lullaby that induces a very pleasant semi-stupor. Ahh, that's the Rachmaninov magic.
Towards the end of the movement, the full symphonic complement of 70 or so instruments lend their support, with brass punctuation marks that may startle you with their heft and weight, not to mention the vast soundstage acreage they occupy. Soundstage dimensions, layering and imaging get excellent grades.
There's no doubt the ATM-3s sound marvelously acoustic. All instruments are notably full-bodied, with dense tone and rich timbre and there's a holistic quality across the stage.
Impressive as that was, the following crescendo at the beginning of the third movement jiggers it up exponentially. The fortes come at you so cleanly and artifact free, the transient is so coherent, you may be inclined to think these amps are speed demons. They really do deliver near perfect frequency alignment, which goes a long way toward generating the impression of uncommon speed.
Afterwards, I asked Lynn, "That's pretty impressive. Does it need anything? Does it want adjustment anywhere?" Her head swiveled left to right and she replied, "The last time we had beguiling sound like this was with the Tenor 175S stereo hybrid amp (MSRP $55,000)." Yes, it's true tone and body are similar, although the Tenor has more timbral color, resolution, and wider dynamics—more of everything. It's also in a different price category. A fairer comparison would be to something like the McIntosh Mc2301 monos (MSRP $24,000). Alas, I haven't heard these.
Here's a little gem I came across recently with knockout sound: Ella Swings Lightly (Verve, MG VS-64021). This release won Ella the 1960 Grammy award for "Best Jazz Performance, Soloist." It's as good as her well-known Clap Hands LP.
Ella is not as svelte and refined as the last time I played this record with the Soulution 710 amp. Detail retrieval is sufficient—you will hear the soloists' heavy breathing and the like—but you won't get as much info on the bottom, nor is the top as finely delineated. The ATM-3 paints with a broader brush, plus it does not emphasize details and push them into the foreground, like some amps. Micro-dynamics and resolution meet expectations, but they don't approach the Soulution level.
But the ATM-3s compensate in other ways. Ella's vocal apparatus is warm and buttery and, man, has she got body. The brass orchestra backing her may actually sound better because of their increased heft and dynamic power. Note, however, that same quantity of body and weight compromised transparency to a degree.
Dynamic prowess is profound. While both amps sport 110 watts into 8 ohms, the ATM-3 displayed noticeably more headroom. I discussed this with the importer, who promoted the idea that Air Tight tends to be conservative in their specs. It's quite likely the ATM-3 would measure considerably higher on a test bench. Again, I was reminded of the Tenor 175S, with its 175 watts into 8 ohms.
Listeners' reactions varied widely, depending on which side of the audio spectrum they gravitated to. Those partial to the Good Old Days, especially fans of classic Blue Note LPs, were in love. They thought the ATM-3s excellently blended the virtues of both camps.
On the other hand, modern tube amp guys, while recognizing the quality and even enjoying the sound, were left unimpressed by the classic aspects of the ATM-3s.
One point that kept cropping up in my notes is their calming effect: the ATM-3s are infectiously acoustic and relaxing. This may or may not be considered a caveat, but it does mandate careful choice of ancillary gear. If you pair the ATM-3s with other relaxed sounding gear, you may find your attention wandering. Once when I swapped in some new arrivals, the small talk went on throughout the session, an indicator that the panel was not engaged.
Fit-n-Finish and Cosmetics
The look of the ATM-3 is traditional. Fit-n-finish is average, only the thick, gun metal grey faceplate exhibits a degree of luxury. The sides and top are thin, black, anodized aluminum. See the website for details on the several controls.
Each amp weighs 55 lbs., not much compared to the behemoths I'm usually listening to. They take up a fair amount of floor space and they do run hot—too hot for you to touch the top of the chassis.
The supplied footers are well-made and work well—no need to experiment with third-party options.
As each ATM-3 has a volume attenuator knob on the front panel, theoretically, you could forsake your pre-amp altogether and just use these, like a preamp with dual-mono volume pots. However, the importer recommends using a preamp because you'll be driving the amps with more voltage and get better micro-dynamics. Turn the volume attenuator all the way up on each channel and leave it there. The ATM-3 has low input sensitivity (you need less voltage to drive them); your speakers will play louder at the same volume setting on your preamp. I had to adjust my line stage volume down quite a bit.
I started out using the 4 ohm taps for my YG Anat Signature speakers, based on the speaker specifications. Something told me to try the 8 ohm: the unexpected happened. The sound got tighter and the relaxed quality diminished. Just goes to show you—take what the manual says as a starting point. Exercise your options.
Flipping the Switch to Triode
Along these lines, the amp can operate in either triode or ultralinear mode with the flick of a toggle switch. I had been running in ultralinear because, to me, triode means sweet, bloomy, and indistinct, plus power drops to 55 watts. The importer advised giving triode a shot anyway, even after I expressed these concerns. In fact, we made a gentleman's wager.
I'll collect when he comes to town. It was not my cup of tea. Some people may like triode mode. I was reminded of my early days in audio when I owned SET amps—the classic aspects redoubled.
The Stage III Kraken Power Cord
I ensconced the amps in Kubala-Sosna Elation! single-ended interconnect (the amps only support S-E inputs), speaker wire and power cords. No power conditioning.
If you want to supercharge your amps, try connecting them to the wall with a Stage III Kraken power cord (MSRP $8,400). This cord has the amazing effect of multiplying dynamic power and at the same time dropping the noise floor significantly. A monster of a PC, there's nothing like them for conveying orchestral power. I also find they work well connected to preamps.
Air Tights' chief designer, Miura-san, is nearly 80 years old and has been in the audio industry for about 60 of them. He has deep knowledge and a very advanced esthetic of what makes good sound. He insists on hand-wiring, point-to-point connections (no circuit boards inside) and hand-made parts. After that much time, you develop personal relationships. For instance, Air Tight power transformers are custom designed and hand-wound, sourced from a family business known as "Grandma and sons" located near Fukushima.
Each amp uses three pairs of 6CA7 tubes working in parallel, which Air Tight calls triple push-pull configuration. Tubes are current production. All parts and tubes are carefully selected and it is not recommended to seek upgrades.
In the broadest terms, one can envision tube amps in two voicings. There's the classic, which favors musical attributes, and the modern, which measures well on the test bench and aims for neutrality. These are the extremes; most amps fall in the vast, grey middle.
Upon first listen you will likely place the Air Tight ATM-3 mono amps in the classic category. The evidence is in its musicality, sweet tone, and the handling of the top, bottom and midrange. Air Tight is known for its musical profile.
However, it didn't take long to determine the Good Old Days attributes were not excessive, while the modern virtues—dynamics, definition, speed, soundstaging—were done quite well, just not to the nth degree like my Soulution 710. Sound-wise, the ATM-3s have no real issues. With minor tweaking, I got them sounding really good.
Frankly, I don't know why the Air Tight ATM-3 mono amps are not better known. Modern school acolytes enjoyed them, even while noting their colorations. However, partisans of the classic school loved these amps. They thought the ATM-3s were the cat's meow—a successful blend of classic and modern attributes. Although $21,000 is not cheap, if the shoe fits, it behooves you to get acquainted with the ATM-3s. You'll have to look far and wide to find competitive performance for the price. Marshall Nack
Air Tight Division