Audio Database


In commemoration of the 15th anniversary of A & M, this is the first model of the 21st century, a bulb-tube type monaural power amplifier.

The ATM 211 was planned as the second series of the Single-Ended Triode Amp following the ATM 300 b. A direct-heating triode tube 211, which has been used as a transmission tube at broadcasting stations, is used at the output stage.

The output stage is non-feedback (0 db), and the vacuum tube drive amplifier style of all 3-pole tube configuration is adopted in order to pursue the sound of the direct-heating 3-pole tube 211.

Class A operation is adopted.

Output tube cathode follower High power is pursued by direct drive.

Heater hum is removed by DC ignition of 211 filament.

The output tube electrolytic capacitor is protected by a muting circuit that employs a relay to extend the life.

The power supply section uses a power transformer with separate windings for each circuit of the amplifier stage / bias / heater / relay to reduce mutual interference.

Wide-band tamura large transformer is adopted.

By adopting a bias check circuit, the operation status of the output tube can be confirmed.

Model Rating
Type Monaural power amplifier
Output 22W (8 Ω)
Frequency characteristic 20 Hz ~ 20 kHz ± 1 dB (22W)
Input impedance 100k Ω
Vacuum tube used 211 : 1
12AX7 : 1 piece
12BH7 : 1
External dimensions Width 390x Height 260x Depth 360 mm
Weight 26kg