Two Lux men who would not give up valves.

Air Tight is the brand of A&M Ltd. (エイ・アンド・エム株式会社), a valve-amplifier maker founded in April 1986, according to its listing with Japan’s International Audio Show association. Its founders were Atsushi Miura and Masami Ishiguro, both from Lux, the Osaka company now known as Luxman. The company is often placed simply in “Osaka”; its address is in Takatsuki, a city in Osaka Prefecture between Osaka and Kyoto.

Miura had spent nearly three decades at Lux. In a history of his career published by Air Tight’s former American importer and credited to Miura himself, he says he joined the company on graduating from university in the 1950s, worked first in purchasing and on building an amplifier factory, and in 1961 married Mari, the eldest daughter of Lux co-founder Mr. Yoshikawa, “thus becoming a member of the LUXMAN family.” From 1977 to 1980 he ran the American affiliate, Lux Audio of America, in New York, where he saw the new American high-end makers such as Mark Levinson; he retired from Lux in 1985. The Absolute Sound described him as a past general manager of Lux.

Ishiguro was a Lux man too: Miura told the magazine analog, in an interview published by Phile-web in December 2017, that he had interviewed and hired him — a law graduate of Ritsumeikan University and a keen amateur amplifier builder — and that Ishiguro strongly opposed the industry’s move away from valves and output transformers. “He and I started making them together,” Miura said; “that was the beginning of Air Tight.”

A name chosen for the catalogue.

Miura explained both names in the same 2017 interview. At American shows, he said, catalogues listed brands alphabetically, so he wanted a name beginning with A. The company name came from initials — Atsushi, Masami Ishiguro, and his wife Mari — and the brand name from the valve itself: the company was committed to vacuum tubes from the start, and a tube is airtight. Some English-language retailers explain “Air Tight” differently, as “tight bass”; we give Miura’s own account.

The first product was the ATM-1, a stereo power amplifier using EL34 valves in push-pull for 36 watts per channel, released in April 1986, Phile-web reported in 2024. It was followed by the ATM-3, an EL34 triple push-pull amplifier of 110 watts, which Miura said took five years to develop and which, used by a dealer in Denver to drive difficult loudspeakers, began Air Tight’s reputation in the United States. Later models include the 300B-based ATM-300R, the 211-based ATM-2211J, the ATM-3211 monoblock — another five-year project, Miura said — the ATC-7 preamplifier, phono stages, step-up transformers and moving-coil cartridges, including the Opus-1, which Phile-web said was sold only outside Japan.

The brand stayed analogue by choice. Miura said that around 1995 he was urged to put the Air Tight name on a CD player and refused. The Absolute Sound named him a charter member of its High-End Audio Hall of Fame and gave him a chapter in its Illustrated History of High-End Audio; Phile-web said in 2017 that he was the second Japanese honoured in its Hall of Fame.

Japan’s boutique tradition.

Japan supports many small hi-fi makers, and several in this guide were started by people from the big names. Air Tight’s founder, Atsushi Miura, had been at Lux, now Luxman, before he set up A&M in 1986, according to a 2017 Phile Web interview. Leben’s Taku Hyodo also worked for Luxman, his company says, and Soulnote’s parent, CSR, was founded in 2004 by former members of Marantz Japan, according to Soulnote.

Others came from outside hi-fi. Aurorasound’s Shinobu Karaki spent almost 30 years at Texas Instruments Japan, his company says; Phasemation belongs to Kyodo Denshi Engineering, mainly an automotive-electronics firm; Kiso Acoustic was founded by a collector, Toru Hara.

Valve amplifiers remain central to this world: Zanden says it mainly makes products that use vacuum tubes, Leben calls itself a maker of tube amplification, and Air Tight says it holds to valve amplifiers. The Tokyo publisher Stereo Sound, whose founder held that no measuring instrument surpasses human sensibility, Japanese Wikipedia says, ran a quarterly devoted to valve equipment until October 2025. Its Grand Prix counts for small makers: Kiso Acoustic’s HB-1 won in 2009, and Phasemation says it was honoured in 2025.

The seven are not gathered in one district. Air Tight is in Takatsuki and Zanden in Kishiwada, both in Osaka Prefecture, and Leben in neighbouring Amagasaki; Phasemation and Aurorasound are in Yokohama, Soulnote elsewhere in Kanagawa, and Kiso Acoustic in Nakatsugawa, Gifu, according to their own websites and listings.

This guide sets out what can be checked about each brand — who founded it, who owns it, and what it says about where its products are made — and marks clearly what rests only on the company’s own word.

Hand-wired in Takatsuki.

Atsushi Miura died in May 2022, aged 88; an obituary notice citing the company gives 25 May, while The Absolute Sound gave 27 May. His son Yu Miura became president in 2022, and the company moved that May into a three-storey building in Takatsuki, with a listening room and office on the ground floor, the workshop on the first floor and storage above, Phile-web reported after a visit published in June 2024. It counted 12 staff, including a design team of two engineers who joined in 2015.

The same report described how the amplifiers are made. Six builders each assemble a batch of five units — six for monoblocks — from parts to final test, wiring by hand and avoiding printed circuit boards as far as possible, a practice the company said dates from its founding; the monocoque chassis of the ATM-300R is made by a partner factory. Each builder sound-checks his own work, a model takes one to two months, orders came mainly from Germany and the United States with China growing, and the lead time was about 11 months. Because staff know every part, the company says, every model back to the first can still be repaired. A&M says it builds “Made in Japan” amplifiers “handmade by our own craftsmen” and exports to 47 countries; we give those as its claims. In Japan it also distributes Transrotor turntables and Critical Mass Systems racks. Its official site is airtight-am.net.

For a design guide, Air Tight shows how a small company can carry a large maker’s craft forward under its own name. Compare Luxman, where both founders worked, and Leben, another Japanese valve-amplifier workshop. For this guide we use valve amber, black and cream with a serif, an unofficial interpretation; no product or logo is reproduced.

Keep Air Tight’s identity on hand — save it to a board in the Made Good inspiration library.