MA-3 Mk. 3.1

The MA-3 is the culmination of a massive project Atma-Sphere began in 1998 at the behest of one of their customers. It was 7 years in design, with 15 different chassis and 12 different circuit concept explorations. The goal: to build the largest OTL amplifier the world has ever seen, while at the same time retaining the qualities our amps have made famous.

There is clearly a need for such an amplifier that can make serious power while being completely transparent and musical; fortunately Atma-Sphere OTL technology is well-suited to the task. Since Atma-Sphere is not limited by issues that plague conventional amplifier designs, the MA-3 retains a wide bandwidth and low distortion simultaneouly. No transformer-coupled amplifier can produce 200, yet alone 400 watts and get it right at every audio frequency; yet the MA-3 makes 500 watts easily, without electronic artifacts. It's high-power amplifier that is fast and truly musical!

The MA-3 has all of the features as the other models in the lineup, plus a few not seen in any other amplifier ever produced. It is class A, all-triode, and fully differential, with the patented direct-coupled output circuit and patented automatic bias control. There is only a single gain stage in the amp, so the signal path is very direct - something unknown in amps of this class. And with all it's customised components, including custom precision Caddock resistors and tailor-made filter capacitors, it is one of a kind inside and out.

The overall output power of the MA-3 can be varied by turning on or off banks of output tubes; the amp can operate on 1/3, 2/3, or all of the output tubes. This makes the amp very easy to live with! Of course, even at lower power levels, the MA-3 retains the innate authority and musical character that defines it as state-of-the-art.

Furthermore, the MA-3's power supply has a built-in AC line processor that regulates the line voltage coming into the amp! As a result, line voltage has no effect on the MA-3; it will make full power even if the AC line level has dropped to only 100 Volts.

Atma-Sphere included a very easy to use built-in tube tester (which can be used at any time the amp is on), allowing one to test the output tubes 'on-the-fly' in a matter of seconds. Bias and DC offset functions are automated, using an Atma-Sphere-patented method, with meters to monitor the tubes, output power, line voltage and other features.

Specifications

Output Power

500 watts per channel, 2-16Ω

Impedance

Input Impedance: 100 KΩ single-ended, 200 KΩ balanced
selectable to 600 ohms

Input

2.5 V sensitivity
RCA and XLR true balanced input

Tube Complement (per channel)

42 x 6AS7G output tube
12 x 6SN7 driver tube

Gain

23dB ( for 8 Ω )

Power Bandwidth

2Hz-100KHz within ½ dB

Frequency Response

( 1 watt, open loop ) 20 Hz squarewave Tilt; unmeasureable
1Hz-200KHz within 3 dB

Distortion

Total Harmonic Distortion ( THD ) typically 0.5% at full power
Intermodulation ( IM ) distortion typically under .004% at full power
Phase shift less than 1° @ 20KHz

Output Section Risetime

600 V/µs

Power Storage Capacity (per channel)

1/4 Farad

Power Supply Weight (per chassis)

152 lbs ( 68.9 kg )

Power Supply Dimensions (per chassis)

34" deep x 21" wide x 12.5" tall (86 x 53 x 32 cm)

Amplifier Weight (per chassis)

80 lbs (36.3 kg)

Amplifier Dimensions (per chassis)

31.5" deep x 21" wide x 15" tall (80 x 53 x 38 cm)

Panel Meter Functions

VU level
Individual tube condition
Tube Bias status
DC Offset status
AC line voltage
AC line regulator voltage

Warranty

Three year general coverage
One year for output tubes

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