MA-1 Mk. 3.3
monoblock music amplifier 
Recipient of The Absolute Sound's prestigious "Golden Ear Award" in 2000, the MA-1 enjoys an enviable reputation. Now the Mk. 3.3 series builds on 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 rugged, non-magnetic chassis features classic looks with superior layout. Setup of the amplifier is simple with it's automatic biasing system. 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, day-to-day consistency and of course extreme musicality.

Featuring our new custom wire, V-Cap Teflon coupling caps, custom resistors, and all the other extras for which we are known, the MA-1 shines as an example of why our amplifiers are the best amplifiers worldwide, regardless of cost.
  • Balanced Differential Design®
  • Class-A operation
  • Patented Circlotronic® direct-coupled (OTL) output stage
  • Automatic biasing system
  • V-Cap copper foil Teflon coupling capacitors
  • 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
  • Three-year general coverage warranty with one year warranty on output tubes

Output power

140 watts per channel into 8 Ω load
135 watts per channel into 4 Ω load


Input Impedance: 100 KΩ single-ended, 200 KΩ balanced
Output Impedance: ~2.3 Ω (power method standard measurement)


2.8 V sensitivity
RCA and XLR true balanced input

Tube complement

( per channel ) 14 x 6AS7G output tube
5 x 6SN7 driver tube


25 dB ( for 8 Ω )

Power Bandwidth

2 Hz-200 KHz within ½ dB

Frequency response

( 1 watt, open loop ) 20 Hz squarewave Tilt; unmeasureable
1Hz-300KHz 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

( per channel ) 500 watts

Power Supply storage

( per channel ) 600 Joules


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


( per chassis, without tubes ) 36 lbs. ( 16.3 kg )


Three year general coverage
One year for output tubes


Audio Measurements 
Marc Mickelson, February 2002 

Sounds Like...

Laura Dearborn
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Various, user submitted 
For all support requests, or any questions about your Atma-Sphere product, contact us directly at (651) 690-2246 or send us an email.

Optional Features

Power Supply Boost
      uses custom built filter caps for MA-2
Caddock® resistor package

Meter Panel finish options

Gray hammertone
Brushed anodized black
Brushed anodized silver
Brushed anodized gold
Custom finishes available upon request


Jumper plugs for high efficiency speakers
      Replaces tube in the voltage amplifier section of Atma-Sphere
      power amplifiers, thus reducing gain for high efficiency speakers.
      Recommended when efficiency of speaker is over 100.


Balanced Interconnect
Balanced phono cable
      1 meter, DIN to XLR or RCA with ground post to XLR


Contact your local dealer for pricing information.
Or, call (651) 690-2246 or email us with any questions.