Never, if you value your sanity, thumb through a Japanese hi-fi
magazine. If you’re an inveterate hi-fi casualty, the pictures
you’ll see will haunt you the way a girlie mag tortures Adrian
Mole. I never take my own advice, so I pore over these exotic
journals whenever they come my way (hi-fi and girlie). And for
the past four years, I’ve been waiting impatiently for a stab at
the electronics from Air Tight.
I admit that the charm of the name, the absolute perfection of
that moniker for a brand of valve amplifiers, caught my attention
as much as did the obviously exquisite manufacture. The price,
too, appealed, considering that these amplifiers promised
peerless construction and attention to detail you just don’t find
this side west of a Jadis. At last, there’s a UK importer, so my
wait is over.
If my assignment sheet is correct, this will be appearing in one
of our High End specials, which means that I’m allowed to wax
lyrical about stuff that’s impractical/over-priced/exotic/bizarre
and un-Quad-like without fear of censure. Okay, gang, this is it:
Air Tight has produced what has to be the audio equivalent of a
The ATC-1 Valve Control Amplifier and ATM-1 Valve Power Amplifier
contain all of the right ingredients for rampant audio delirium.
The product descriptions read like a menu for a hi-fi bacchanal,
especially if the diner has a craving for vintage, uh, vintages.
Common to both units are PCB-free circuits, with everything
hard-wired à la Golden Age hardware or our own Croft products.
The valve bases are ceramic, with gold-plated sockets. The
chassis are copper plated and the gorgeous, grey ‘almite
treatment’ faceplates are machined from 8mm aluminum. All of the
valves are genuine brand-name items, like Siemens and Pentalab
rather than whatever-you-can-get throwaways from China. They’re
the closest things to jewelry that this industry has produced,
in terms of finish, appearance and attention to detail. In other
words, they’ve been assembled with the kind of fanaticism you
find only in Tokyo or Teheran.
The preamp is deceptive because it’s so petite, measuring only
430x90x325mm (WHD). As with Counterpoint and other makers of
slim line valve preamps, Air Tight mounts the five 12AX7s (ECC83s)
horizontally. And as with Lux, who couldn’t resist mounting the
valves on the front of their hybrid ‘Brid series integrateds, Air
Tight mounts three of the little beauties so that they can be
seen from the left-hand side of the case. The gorgeous front
panel provides source select for phono (m-m only), tape monitor,
mono/stereo select, attenuate (full muting), balance, volume and
on/off, plus an orange tell-tale. The controls are among the
smoothest, most luxurious I’ve experienced, but I must resist the
salacious adjectives which come to mind.
At the back, all is gold-plated, with inputs and outputs
corresponding to the front controls, but with two extras. In
addition to the main outputs there’s a spare set for feeding a
second power amp and a pair of sockets tagged ‘EQ out’. The
latter takes the phono signal from input through RIAA circuitry
and straight out again, for feeding directly into the ATM-1 power
amplifier, bypassing every unnecessary switch and stage in the
preamp. This can be used in tandem with the standard outputs for
some curious purist combinations.
The circuit itself is based on vintage concepts, just like the
PCB-free construction, and consists of a three-stage
low-impedance equalizer described as ‘once employed by the
Marantz 7’; this is the stage fed straight to the EQ Out sockets.
The single stage line amp is devoid of tone controls or filter
circuits and features low-impedance cathode follower output. The
power supply employs a solid-state ripple filter circuit for
suppressing mains hum and noises. Despite the size of the
enclosure, which would suggest the use of a compact toroidal
transformer, Air Tight opted for an EI core type because it
provides ‘sharper attack of sounds’. The cores are wrapped in
silicon steel plate and copper plate to ensure perfect shielding.
The power supply, phono and line stages are totally independent
and the latter two are fully shielded. The chassis was made
deliberately heavy to help minimize vibration and component
interaction. All tubes are pre-aged and fitted to the
aforementioned gold-plated sockets in ceramic bases.
The ATM-1 power amplifier is based on Mullard research and
employs four 6CA7 output valves from Siemens for a rated output
of 36W/channel. For protection to the output tubes, Air Tight
uses 5AR4 in parallel at the rectifying stage instead of a diode,
to better cope with large current. (I don’t have my RCA or Babani
guides handy, but I think they’re equivalents to the GZ34 in my
cherished Dynaco…) The output transformers, deemed by many
current amp builders as harder to find than good tubes, are the
highly-rated Tamuras, used in the Japanese broadcasting industry.
Air Tight operate the amplifiers for 100 hours before they’re
‘retuned’ and dispatched. Aside from a valve cracked in transit,
these piece have proven to be the most trouble-free and ghostly
silent tube products I’ve used in recent memory. It also explains
why Air Tight insisted on air-mailing to me a selected 12AU7
rather than risk any sonic compromises from my probably iffy
stock of mystery brand tubes.
The amplifier features a bit more than the minimum socketry and
on/off switch. Across the front are two sockets and three rotary
controls in addition to an on/off button and tell-tale to match
the preamp. The sockets accept a CD player straight in, while the
first rotary chooses between the front panel inputs and the main
inputs at the rear. The other rotaries are left and right volume
controls for the source fed in via the front sockets. These
sockets, by the way, bypass certain parts of the amplifier’s
circuitry, connecting the input directly to the first stage
valve. At the back are the main inputs and the speaker terminals;
the arrangement with the front panel ‘front/rear’ selector allows
purists to feed the CD player into the front sockets, with the
preamp and therefore the other sources left permanently installed
at the back. Naturally, using the preamp in its EQ Out mode for
optimum phono playback would require the use of the front sockets
and hence the volume controls.
My only complaints about the presentation involve the diabolical
speaker terminals, those daft constructs which only accept bare
wire. Considering the prices of these units, I would imagine that
importers could specify something a bit more practical for the
models they’re importing, like Michell or Monster multi-way
binding posts. Anyway, there are three terminals per channel
rather than two, which allow for the selection of either four or
eight ohm operation.
(A couple of other details of the review samples will probably be
changed when regular stocks start arriving. These include
three-core, blue/brown/green-yellow mains wiring, the blocking
off of the extra two-pin mains outlet and the provision of a
grill or cage to cover the valves and protect them from prying
I used the Air Tight combination with the Oracle Delphi II
turntable, SME V tonearm and Audio-Technica ART-1 cartridge, the
Marantz CD-12 CD player and the Sonus Faber Electa Amator and
Celestion SL700 loudspeakers, with a variety of wires including
Master Link, Mandrake, Lieder, Sony LC-OFC and Monster M1. And I
immediately hit on two mismatches.
Trying to think like the kind of anachrophile who would have
designed these items, I’m assuming that the company anticipated
use with high-output vintage cartridges like Deccas or m-cs like
Ortofon SPUs with onboard transformers. Sure, I could get some
sounds, but headroom and maximum level were in short supply, so I
did my ‘quiet’ listening with the ART-1 fed straight in and my
head banging with the Classic step-up in place. The other mismatch
was the Celestion SL700, which needs more juice than this baby
can muster. Again, I could get some positively dandy sounds out
of the ‘700s, but bo way would it cope with the odd crescendo.
But because sound — if not the levels — was so enticing, I
spent as much time driving the ‘700s with the ATM-1 as I did the
easier Sonus Fabers. Thinking like the Japanese, though, would
suggest that most of these will end up driving some
hyper-sensitive classics like Lowther horn systems. Mind you, I
had so many combinations to try out, what with the bypass mode
and the CD Direct inputs, that I stopped worrying about it and
treated the reconnections like a daily chore. Like shaving.
Fortunately, the long build-up between the time I first learned
of the Air Tight and the first listen was rewarded with some of
the mostly gloriously lush and musical sounds I’ve heard since
running an SPU into elderly Marantz and Dynaco tube electronics
through the AR 2AXes. Talk about a blast from the past…
Actually, that’s unfair, because the preamp sounds ‘younger’ than
the power amplifier, most of the Mills & Boon effects coming from
the ATM-1. As I tried the preamp with the Aragons into the Divas
and drove the amplifier both directly from CD and with the Audio
Research SP-9, it was easy to attribute characteristics to the
pair’s respective halves.
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