Atma-Sphere M-60 Mk. 3.3 OTL Monoblock Amplifiers

Tubed power amplifiers
Atma-Sphere Music Systems M-60 Mk. 3.3

Wrapping up the listening with an all-time favourite tune, Toto’s ‘Africa’ [Toto IV, Columbia], a song that was on the radio a lot when I first encountered Atma-Sphere as a company in 1982. Africa offers up a compelling mix of percussion and vocal harmonies that have made it a classic rock staple. The M-60’s brought out the best in this SACD recording with drums, xylophone and marimba’s anchoring syncopated rhythms that drive the song forward. Soaring vocals moved along across a wide and clear soundstage. The rains were indeed blessed. 

The Atma-Sphere M-60 Mk 3.3 power amps proved to be sonic marvels. The classic ‘Pace, Rhythm and Timing’ was joined by body, space and dimensionality. There was also that hint of tube magic without any overbearing coloration. Things sounded as they should with just enough colour to provide a sonic character that would keep me coming back for more. Truly one for the music lover. 


Type: valve power amplifier

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

Tube complement: 8 × 6AS7G output tubes and 4 × 6SN7 driver tubes per channel

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

Gain: 20dB (for 8 Ω)

Power Bandwidth: 2Hz–75KHz 
within ½ dB

Frequency response: 1Hz–200KHz 
within 3 dB

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 

Feedback: 1 dB

Dimennsions (W×H×D): 43 × 20 × 33cm per chassis

Weight: 13.6kg per chassis (without tubes)

Price: $7,700/per pair USD

Manufacturer: Atma-sphere

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