Atma-Sphere M-60

Atma-Sphere M-60

Atma Sphere M-60

Hi-End Audio Tube Amplifiers, 2 x 60 Watts, OTL monoblocks, Mk 3.3

For years now the M-60 in its various forms has been the subject of the Soundstage! Hall of Fame Award, The Absolute Sound Golden Ear Award and Editor’s Choice, with numerous accolades in the press and on the web.

The M-60 Mk. 3.3 continues that tradition with classic styling and its award-winning state-of-the-art performance. The M-60 gives you the features and precision performance of our larger models in a beautiful, 60-watt package. The amp operates class A and is unconditionally stable with reliability proven over many years.

The power tubes are inexpensive, readily available and do not require any matching. Sporting a classic, open-chassis construction, the M-60 Mk. 3.3 sets the bar for hi-end amplifier performance.


– Balanced Differential Design®
– Class-A2 operation
– Patented Circlotronic® direct-coupled (OTL) output stage
– Dual-mono chassis construction
– Automatic bias – no adjustment needed
– Built in VU meter for tube and output monitoring
– Easily monostrapped for greatly increased power
– Standby switch for long output tube life
– 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 electronics – no circuit boards!
– 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, one year warranty on output tubes

Output power
60 watts per channel into 8 Ω load
45 watts per channel into 4 Ω load
80 watts per channel into 16 Ω load

Input Impedance: 100 KΩ single-ended, 200 KΩ balanced Output Impedance: ~4.1 Ω

3 V sensitivity ( for full output )
RCA and XLR true balanced input

Tube complement
8 x 6AS7G output tube ( per channel )
4 x 6SN7 driver tube ( per channel )

20dB (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

Power supply storage
140 Joules ( per channel )

Total Harmonic Distortion (THD) typically 1% at full power.
Intermodulation (IM) distortion typically under .04% at full power.
Phase shift less than 1° @ 20KHz

Output section risetime
600 V/µs

1 dB

Power consumption
300 watts ( per channel )

Dimensions & Weight
13″ deep x 17″ wide x 8″ tall (33 x 43 x 20 cm) per chassis
30 lbs (13.6 kg), per chassis, without tubes

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