Credit: Tube Kingdom, Vol. 86, Autumn 2017, Stereo Sound Publishing, Inc.

【Tube Kingdom, Vol. 86】
A preamplifier for the next generation released by A&M.
A broad sound field for a fresh and clear presentation of music.
A high signal-to-noise ratio that allows you to experience the atmosphere of a string
concert.
A thick mid-range that can only be created by a tube amplifier.
Nobuyuki Fu

I always accept requests for interviews and write articles for general magazines whichare, of course, not specialized in audio products. This is because I want as manypeople as possible to know the pleasure of audio. Even editorial departments of generalmagazines show interest in tube amplifiers and want to publish articles about them.
However, they have this fixed idea that tube amplifiers are only suitable for listening
to jazz with its warm, thick sounds, and it takes time to get them to shake off thisidea. So, the best thing to do is to have them listen to the sounds of the ATC-5 andI made arrangements to play some music using this new product. The music played bythe ATC-5 has a broad sound field with fresh, clear acoustics.
As for Airtight’s earlier tube preamplifiers the ATC-1 and ATC-2, the supply of parts
has been partially discontinued and stocks are about to run out. Of course, the ATC-1
is a long seller and has been in the market for over 30 years. The subsequent ATC-2
is a stereo line-control ampliﬁer, whereas the new product, the ATC-5, is a stereoline & phono control ampliﬁer similar to the ATC-1.
The ATC-5 phono equalizer employs two-stage NF-CR type circuitry, perfectly
controlling the lowest range (described later). As regards the tubes, for the phonoequalizer, three 12AX7 tubes are used for a stable supply, while for the line amplifier,two 12AT7 tubes are utilized. As for the resistor, they use the Vishay Dale metal
foil resistor or the Tokyo Ko-On Denpa RN65. However, using expensive ones does not
simply produce good sounds. This is especially true for the first-stage cathode as,
by using them at key positions, sounds can be better controlled. This contributes
to a high signal-to-noise ratio, a factor that I recognized when I tried listening
with ATC-5. As for the volume control element, an Alps controller is employed, andthis option is considered just about the only mechanical volume controller for qualitymachines.

底板を外して内部を見る。真空管は写真右の側板内側にイコライザー部の 12AX7×3 本、写真中央にラインアンプ部 12AT7×2 本を配する。イコライザー部とラインアンプ部の効率的なレイアウトを考慮して L 字型の基板を用い、高さ 90mm の薄型の筐体を実現するために L／Rch の基板を表裏の上下 2 段としている。配線は手配線で行なわれている。
The ATC-5 hardly uses any printed circuit boards, and is primarily manually wired.
In fact, printed circuit boards are not used at all for the signaling component.
Additionally, Airtight promptly has introduced mechanical sound creation not only
for its electrical network, but also for the structure of the chassis. By hanging
a 1-mm-thick inner chassis in the traditional 1.6-mm-thick steel main chassis withits monocoque structure, the company has been able to adjust the sound quality of
its new product, the ATC-5.

Switches and knobs: From left: Switchingfor 2 MM inputs, balance adjustment,

リアパネルを見る。中央から右へ 2 系統のinput selector for phono and 3 lines,

Rear panel: From center to right: RCA

on/offunbalanced terminals for 2 outputs, 3(mute)switch,andvolumecontrol.

line inputs, 1 phono equalizer output,
and 2 phono inputs.

Upper center of the image: RK501 volume
controller by Alps, an optional extra for use withpreamplifier ATC-2 for higher quality sounds.

Note that the ATC-5 is equipped with the RK501
as standard.。
As mentioned above, the sounds produced by the ATC-5 clearly break away from the ideathat tube amplifiers create warm and thick sounds. Its sound output is elaborate inevery detail, unclouded and clearly defined, leaving one feeling completely satisfied.
The signal-to-noise ratio is high. A string ensemble of 192/24 high resolution crisply
stretches out and sounds pleasing to the ear. You can feel the atmosphere and thedepth of tone, as the sound extend to both sides. From my experience, the extent towhich this tube amplifier is able to produce an invigorating expression of sounds
is truly valuable. Though its chassis is thin at 9 cm in height, the sound expression
is not cramped. Furthermore, it is a tube amplifier that really does have a thickand smooth mid-range. Airtight says that their aim was to express the atmosphere
produced by a modern high-end amplifier with high clarity and exciting sounds to listen
to.
The sounds of analog discs are also clear and broad, unlike the old-fashioned
expression that was soft and thick. For its step-up transformer for MC cartridge,
it combined its own ATH-3.
Nowadays, it is common to use multiple speakers with small- to mid-size woofers. When
playing analog discs with these speakers, the cones of the woofers sometimes become
shaky. So, to enable the phono equalizer to reproduce good-quality sound, Airtightdevised ways to offset the warps and face deflection of analog discs, as well as thevibration of the pickup. The time constant is rolled off at ⊖6 dB and 30–40 Hz for
the EQ stage and set at ⊖ 18

dB and 10 Hz for the line stage. When we conducted

our listening trial, we used a Bowers & Wilkins floor-standing speaker, the B&W 800D3,
and hardly felt any vibration when we touched the cone of the woofer.
A quarterly magazine for audiophiles, Tube Kingdom, choses the Airtight ATC-2HQ as
its reference preamplifier. The ATC-2HQ is superior in its depth of shades, and its
deep, solid sounds. However, the ATC-5 expresses sound in a flowing, neat and also
attractive way. I feel that its sounds herald a new era for Airtight.

Mr. Nobuyuki Fu, checking the controllers of ATC-5
Preamplifier
AirTight ATC5
●Input：PHONO2（MM、RCA unbalance）、LINE3（RCA Unbalance）●Output：2（RCA Unbalance）●Input Impedance：47kΩ●Gain：40dB（PHONO）、18dB（LINE）●Load Impedance：>47kΩ
以上●Output Voltage：20V●Tubes Incorporated：12AX7×3（EQ）、12AT7×2（Line Amp）
●Dimensions/Weight：W400×H90×D260mm／9kg●Contact ：A&M Limited TEL072（678）0064
Analogue player used for the listening trial:
Michell Engineering
GyroDec-UNV2, 610,000 yen
Contact: Tosy Corporation
MC cartridge:
Phasemation
PP2000, 440,000 yen
Contact: Kyodo Denshi Engineering Co., Ltd
Credit: Tube Kingdom, Vol. 86, Autumn 2017, Stereo Sound Publishing, Inc.