The MA-3 is the culmination of a massive project we began in 1998 at the behest of one of our
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. The end result is arguably the the best amplifier in the
There is clearly a need for such an amplifier that can make serious power while being completely
transparent and musical; fortunately our OTL technology is well-suited to the task. Since we are
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 our other models, plus a few not seen in any other amplifier
ever produced. It is class A, all-triode, and fully differential, with our 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.
We 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.
500 watts per channel, 2-16Ω load before clipping
Input Impedance: 100 KΩ single-ended, 200 KΩ balanced
selectable to 600 ohms
2.5 V sensitivity
RCA and XLR true balanced differential input
Tube complement (per channel)
42 x 6AS7G output tube
12 x 6SN7 driver tube
1-100KHz within ½ dB
Power Storage Capacity
1/4 Farad per channel (more than any production amplifier)
Frequency response (1 watt, open loop)
20 Hz squarewave tilt: unmeasureable even at full power
1Hz-200KHz within 1/2 dB
Total Harmonic Distortion (THD) typically .5% at full power
Intermodulation (IM) distortion typically under 0.004% at full power
Output section risetime
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
Individual tube condition
Tube Bias status
DC Offset status
AC line voltage
AC line regulator voltage
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For all support requests, or any questions about your Atma-Sphere product, contact us directly at (651) 690-2246 or send us an email
Contact your local dealer
for pricing information.
Or, call (651) 690-2246 or email
us with any questions.