Предусилители — Air Tight ATC-3

The ATC-3 is a valve line preamplifier from Air Tight, the Japanese brand of A&M, whose products are hand-built at its factory in Osaka. It was released in 1998, and Air Tight classes it as a tube type line control amplifier. Air Tight designed it for the era of SACD and DVD-Audio, with the stated aim of getting the most out of digital sources. In Japan it was listed at JPY 280,000 in standard form and at JPY 340,000 with the luxury volume option.

Key specs that matter

Three valves are used per unit - one 12AX7 (ECC83) in the first stage and two 12AU7 (ECC82) in the second. There are five line inputs and no phono section. Rated output is 2 V, and the maximum output reaches 15 V. Input sensitivity is 110 mV for 1 V of output, and total harmonic distortion is quoted at 0.01% or less. The frequency response runs from 5 Hz to 100 kHz within 1 dB, while noise sits 90 dB below signal with IHF-A weighting. The chassis measures 430 mm wide, 90 mm high and 325 mm deep, and the unit weighs about 8 kg. The mains cable is detachable.

Engineering and use context

The gain circuit is a two-stage flat amplifier with negative feedback, driven at low impedance, and both stages run self-biased. The output uses an SRPP (shunt-regulated push-pull) topology, which Air Tight chose for its high input impedance, low output impedance and low distortion, and a reinforced buffer stage follows it to reject noise and extend linearity. Signal wiring is largely done by hand, with printed circuit boards used only where the company judged them beneficial to improve the flow of the signal. The chassis is built to be rigid so that vibration reaching the valves and parts is kept low. In the power supply, fast recovery diodes act as rectifiers, giving quick operation and low pulse noise. The luxury version replaces the standard volume control with an Alps RK-501 precision potentiometer.

Pairing

With its nominal output and a large reserve before clipping, the ATC-3 can drive power amplifiers that need a strong input signal as well as those with high sensitivity. Sources should be line level - CD and SACD players, DACs, streamers, or a separate phono preamplifier like the Air Tight ATE-3011 for vinyl. The obvious in-house partners are Air Tight valve power amplifiers such as the stereo ATM-1S or ATM-300R.

Alternatives

The Air Tight ATC-6 took over from the ATC-3 as a line stage built around two 12AT7 valves, with three RCA and two XLR inputs in a 400 mm wide chassis.