mono power amplifier


  • At last, unfinished dream came true;
  • Astounding 120W output from exquisite 211 Triode push-pull circuitry!!
  • In 2001, we Air Tight introduced the ATM-211 that delivers hefty 22W output power by means of SET circuit of the transmission triode valve 211. We all were drunk with the unexcelled charm of overall tonal quality inhering in the
  • 211 tube, while it’s also true that all of tube-sound enthusiasts have been longing for high output exceeding 100W/CH with the 211 therein employed.
  • Now in 2017, our ambitious challenge to let the 211 in skilled push-pull configuration yield such gigantic power output was rewarded in the form of the new mono-block ATM-3211, as a result of unyielding 5 years’ patience with uncompromising spirit and unsparing investment in engineering cost.
  • Please enjoy the outstanding, intrinsic sonic features and characteristics of the Triode 211; both of graceful delicacy in pianissimo and clear saturation-free representation in fortissimo! .
  • We may define that the triode is the primitive form of every vacuum tube. Although people might imagine that the triode is left behind the era, on the other hand still there are some persistent triode lovers.
  • Yes, we, Air Tight are one of such triode lovers. Starting from ATM-300 of 300B and ATM-211 of transmission tube 211 to the latest ATM-300Anniversary of our 30 years anniversary.
  • As greedy as it is, this ATM-3211 has been in research for more than 5 years if such simple and vivid triode charm can be realized even for the low efficiency speakers by means of 100w exceeding push-pull circuit.
  • The circuit configuration is as follow:
    • 1st stage: differential circuit of 12AX7
    • 2nd stage: 12BH7
    • Cathode-follower 12BH7 parallel
    • A-class operation up to 30W
    • AB-class operation for more than 30W
    • Wide frequency range is obtained by NFB circuit (Frequency response 10Hz~50kHz ±1dB)
    • Massive Tamura’s output transformer is employed
    • High and low 2-compositions transformer ensure instantaneous power supply and prevent power interference.
  • High grade capacitors and resistors are employed for the key locations learned in years’ development.15mm thick aluminum front panel is scraped out by hand workWBT input and speaker terminals are employed.Wiring and soldering are all done by hand.


Valves employed:
12AX7 x 1, 12BH7 x 3, 211 x 2
Rated output:
120W (6Ω/THD2%)
Frequency response:
10Hz~50kHz (±1dB/THD0.06%)(at 1kHZ/30W)
Damping factor:
Input sensitivity:
1V/Input impedance 100kΩ
Power consumption:
Load impedance:
6Ω/16Ω(Interchangeable, 6Ωstandard)
400(W) x 450(D) x 405(H) mm

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