Integrated Amplifiers

For the continuing evolution of the 39-year-old ATM-1, this amplifier series undergoes a rebirth roughly every 20 years. The original ATM-1 [HFN Aug ’89] derived its output from four 6CA7 beam power pentode tubes and provided two inputs, the second via a pair of phono sockets on the front panel. In 2006, it was modified heavily, renamed the ATM-1s and the output tubes were replaced with EL34s. These also power the latest version, the ATM-1e, which loses the front panel inputs of the previous editions.

While both of the later iterations of the ATM-1 feature circuit refinements, the primary area where the models have evolved is in their valve complement – not just the output tubes. In addition to moving to EL34s, the ATM-1s ‘middle model’ also changed the original input valve lineup which included a 12AX7, two 12AU7s and two 5AR4s for rectification. For the ATM-1s, AirTight changed the 5AR4s for solid-state rectification, which the current ATM-1e retains. The latter swaps the ATM-1s’ 12AX7 and the pair of 12AU7s for a 12AT7 and two 6CG7s.