Power Amplifier Air Tight ATM-2211

Air Tight ATM-2211: Single-Ended Triode Mono-block Power Amplifier

The ATM-2211 is the next-generation 211 single-monaural amplifier, launched to commemorate Air Tight's 35th anniversary. Departing from traditional overall Negative Feedback (NFB) from the output transformer's secondary side, the ATM-2211 applies NFB from the plate of the 211 output tube to the first stage. This design prioritizes sound penetrating power and energy over theoretical measurements. The operating points have been strictly redefined, increasing output to 32W.

Key Technological Features

• Circuit Design: Fixed bias method and DC ignition for the filament. The design omits overall NFB in favor of plate-to-first-stage feedback to enhance sonic energy.
• Power Supply: Independent power transformers for high and low voltage circuits. Featuring a custom hand-crafted choke coil, wound without a traditional bobbin by Japanese craftsmen to withstand high voltage and ensure a transparent soundstage.
• Components: High-output Hashimoto Electric Co., Ltd. output transformers for superior low-end response. A large vertical edgewise meter allows for easy monitoring and bias adjustment.
• Construction: Resonance-controlling monocoque main chassis with a suspended thick pure copper sub-chassis. The front panel is machined from a solid aluminum block, utilizing invisible threaded studs for maximum mechanical strength and electrical conductivity.
• Protection & Connectivity: WBT speaker terminals for 4Ω and 8Ω loads, selectable RCA and XLR inputs. A built-in timer relay ensures a delayed application of plate voltage, protecting the 211 tubes and smoothing capacitors for long-term reliability.