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 Faberge Egg.
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 a 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 brats.)
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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