MA-1 Mk 3.3

Recipient of the Golden Ear Award (TAS 2000), the MA-1 has enjoyed an enviable reputation. Now the Mk. III.2 series builds on the advances of decades-proven technology. An improved output section and enhanced driver circuit contribute to superior low-level detail, smoother sound, wider bandwidth and AC power immunity. The new, rugged, non-magnetic chassis features classic looks with superior layout. Setup of the amplifier is simple with it's automatic tube biasing system. Even the controls and switches are ergonomic without sacrificing performance.

The MA-1 is extraordinary in every way. Not only is normal operation easy on the vacuum tubes, the effect of a tube failure on the unit is entirely inconsequential. Despite its extreme performance, the MA-1 is known for remarkable ease of setup, ease of operation, and day-to-day consistency. You will not be disappointed.

Featuring new custom wire, V-Cap Teflon coupling caps, custom resistors, and all the other extras Atma-Sphere is known for.

  • Balanced Differential Design®
  • Class-A operation
  • Patented Circlotronic® direct-coupled (OTL) output stage
  • Automatic biasing system
  • V-Cap Teflon coupling capacitors come standard
  • Built in VU meter for tube and output monitoring
  • Easily monostrapped for greatly increased power
  • Uses only one gain stage for supreme clarity of sound
  • Proprietary precision components used throughout
  • Low-noise "star" grounding topology
  • Fully hand wired point to point
  • Stable with all input and load conditions
  • Exclusively uses Octal-Triode based vacuum tubes
  • Classic open chassis construction with Wrinkletex™ finish


Output Power: 140 watts per channel into 8 Ω load, 135 watts per channel into 4 Ω load.


  • Input Impedance: 100KΩ single-ended, 200KΩ balanced.
  • Output Impedance: 2.3 Ω

Input: 2.8V sensitivity (RCA and XLR true balanced input).

Tube Complement (per channel): 14 x 6AS7G output tube, 5 x 6SN7 driver tube.

Gain: 25 dB (for 8 Ω).

Power Bandwidth: 2Hz-75KHz within ½ dB.

Frequency Response (1 watt, open loop):

  • 20 Hz squarewave Tilt; unmeasureable.
  • 1Hz-200KHz within 3 dB.


  • Total Harmonic Distortion (THD) typically 0.5% at full power.
  • Intermodulation (IM) distortion typically under .005% at full power.
  • Phase shift less than 1° @ 20KHz.

Output Section Risetime: 600 V/µs.

Power Consumption: 500 watts.

Power Supply Storage (per channel): 600 Joules.

Dimensions (per chassis): 18" deep x 17" wide x 8.5" tall (46 x 43 x 22 cm).

Weight (per chassis): 36 lbs. 16.3 kg) without tubes.

Warranty: 3 year general coverage, 1 year for output tube.



Optional Features: Power Supply Boost - $2,600.