SoundStage! Reviewer's Choice 2004

Golden Ear Award Harry Pearson

Golden Ear Award Jonathan Valin

The MA-2, simply put, is the one of the finest amplifier made anywhere in the world at any price. It is now updated to the Mk. III, with an improved gain stage with even wider bandwidth and greater transparency than before. Switchable feedback has been added as well. Bias is automatic. Audio purists have craved the design features of this amplifier since the beginning of HiFi, but only Atma-Sphere has succesfully put them all in the same place at the same time. The MA-2 Mk. III is one of the most powerful production OTLs available (and certainly the most reliable), with vastly enhanced ability to drive difficult loads. The MA-2 remains 15 years ahead of the competition!

The MA-2 offers total improvement. It has bass impact and plumbs low frequencies that other amps seem unaware of. Yet it is smooth, detailed, tuneful with ultra-speed that belies such a large tube amplifier. You can play it day in and day out without noticeable artifact, unlike many amplifiers in the recent press (to say the least)! The improvement the MA-2 offers is obvious on any system in 5 seconds flat. It is not subtle.

The MA-2 in particular is noted for its superior performance on Sound Lab, Wilson Audio, JM Labs, Magnaplanar and Avalon loudspeakers (90% of all MA-2s built are running on these speakers). These speakers need an amplifier that is capable of serious power, able to bring out the bass capability of the speaker with proper control and impact, while also able to portray detail, delicacy and speed. The combination is unusual in any audio amplifier and something that makes the MA-2 an easy choice.

FEATURES

• All triode
• Class-A operation
• Patented Circlotronic® Output TransformerLess (OTL) operation
• Balanced Differential Design®
• matched V-Cap Teflon® coupling capacitors
• Switchable input impedance
• Handcrafted point to point wired- no circuit boards!
• Mono construction
• Easily monostrapped for more power
• Standby switch for long output tube life
• Automatic Bias
• No tube matching required
• Simple, reliable circuit - one stage of gain
• XLR (true balanced input) and RCA input connectors
• Built with our proprietory custom wire
• Dual AC power circuits for each chassis
• Custom-built Caddock resistors
• "Star" ground circuit for low noise
• Patented black epoxy wrinkletex finish
• Five-year warranty - One year on tubes

SPECIFICATIONS

• 220 watts/channel into 4, 8 or 16 ohm load
• Power bandwidth: 2 Hz - 85 kHz within 1/2 db (open loop)
• Frequency response (1 watt, open loop): l Hz - 100 kHz within 3 dB
• IM Distortion: less than .05% at full power
• THD: less than 1%
• Square Wave Tilt: unmeasurable
• Phase shift: less than 1 degree @ 20 kHz
• Power supply current: 80 Amps
• Input impedance: 100K single-ended, 200K balanced- selectable to 600 ohms
• Output section risetime: 600 V/micro-second
• Output Impedance: ~1.75 Ohms (open loop)
• Power Supply Storage: 1200 Joules in output section, 100 Joules in Driver supply.
• Power consumption: 800 watts/chassis
• Tube complement: 20 6AS7 output tubes and 6 6SN7 driver tubes.
• Dimensions: 28" l x 17" w x 10" h
• Weight: 103 lbs./chassis