The first time i heard about Atma-Sphere was around year 2001, as an end consumer while living in japan. At the time I talked to Ralph of Atma-Sphere on the phone. I was impressed with his friendliness and support. Lo and behold, i met him in person at the rocky mountain audio fest and we hit it off. Good word from Tri Mai (of Triplanar tone-arms) did not hurt either. A hand shake later, we have been happy partners since November 2006 when we started representing these exceptional OTL amps and preamps/phono stages.

Atma-Sphere amps are:

Atma-Sphere preamps (phono stage optional) include:

Information below is copied from Atma-Sphere website with permission from Ralph.

Atma-Sphere Stereo Music S30 MK 3.1

After numerous requests for a lower-powered amplifier, Atma-Sphere unveiled the S-30 at the HiFi ’99 show in Chicago, where it was warmly received (Sam Tellig comments in the August ’99 STEREOPHILE: “I lust after this amp”). The S-30 Mk3.1 improves on the success of it predecessors, is even more compact and easier to use. It is the unchallenged state-of-the-art in low power tube amplifiers. The S-30 Mk3.1 is easy to live with, operate and has the same features as our larger amplifiers.

For audiophiles who seek the ultimate in amplifier design and are realistic about their budget, the S-30 gives you the same precision and performance which has garnered Atma-Sphere’s awards. Operation is simple- bias is automatic. The tubes and output power of the amplifier are monitored with the large VU meter. The amp is stable with any load and uses patented handwired circuitry proven over 3 decades. Built with octal-base signal triodes and a classic appearance, the S-30 outperforms and sounds better than any single-ended amplifier ever produced, not to mention conventional push-pull designs. Its fully-balanced circuitry and proven class-A triode operation make the S-30 the ideal choice for the discriminating audiophile.


  • Exclusively octal triode-based, vacuum tube circuitry
  • Class-A operation
  • Patented Circlotronic® direct-coupled (OTL) output stage
  • Balanced Differential Design®
  • Dual-mono construction
  • Automatic bias
  • Built in VU meter for tube and output monitoring
  • Easily monostrapped for greatly increased power
  • Simple, reliable circuit; only 1 stage of gain employed
  • XLR and RCA input connectors
  • Proprietary precision components used throughout
  • Low-noise “star” ground circuit
  • Fully hand wired point to point!
  • Classic open chassis construction with Wrinkletex finish
  • Three-year general coverage warranty, one year on output tubes


  • Power Supply Boost option – $400
  • V-Cap Teflon® coupling caps $500
  • Caddock® Resistors $1100
  • Meter panel color options: anodized brushed gold, black or silver, no charge


  • 30 watts/ch into 8-ohm load/45 watts into 16-ohm load
  • Power bandwidth: 2Hz-75KHz within 1/2 db
  • Frequency response (1 watt): 1Hz-100KHz within 3 dB
  • THD typically 1% at full power
  • IM distortion typically under .04% at full power
  • Phase shift: less than 1 degree @ 20KHz
  • Input impedance: 100K single-ended, 200K balanced
  • Output section risetime: 600V/micro-sec.
  • Stability: stable with all loads and inputs
  • Feedback: 2db
  • Power consumption: 400 watts
  • Tube complement: 10) 6AS7G output tube
  • 6) 6SN7 driver tube
  • Dimensions: 13″ L x 17″ W x 8″ H

Atma-Sphere Music Amplifier M-60 MK 3.1

Atma-Sphere Music Amplifier M-60is winner of multiple awards including Reviewer’s Choice, Golden Ear, Hall of Fame, and The Absolute Sound 2008 Editor’s Choice.

For years now the M-60 in its various forms has been the subject of the Soundstage!.com 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. 3.1 continues that tradition with classic styling and its award-winning State-of-the-Art performance. The M-60 Mk. 3.1 gives you the features and precision performance of our larger models in a 60 watt, easy-to-live-with package. The amp operates class A and is unconditionally stable with proven reliability. The power tubes are inexpensive, readily available and do not require any matching. Now sporting a classic open chassis construction, the M-60 Mk. 3.1 sets the bar for amplifier performance.


  • Exclusively triode-based, vacuum tube circuitry
  • Class A operation
  • Automatic Bias- no adjustment needed
  • Patented Atma-Sphere direct-coupled (OTL) output stage
  • Balanced Differential Design®
  • Mono chassis construction
  • Easily monostrapped for greatly increased power
  • Standby switch for long output tube life
  • Single stage of gain
  • Rear-mounted XLR and RCA input connectors
  • VU meter for power and tube monitoring
  • Proprietary, precision grade components used throughout
  • Low-noise “star” ground circuit
  • Fully hand-wired electronics; no circuit boards!
  • Classic open chassis construction, with Wrinkletex finish
  • Three-year general warranty, one year on output tubes


  • Custom volume control $1200.00
  • V-Cap Teflon® caps $500
  • Power supply boost $400
  • Caddock® resistor package $1100
  • Meter panel color options: anodized brushed gold, black or silver,no charge


  • 60 watts/channel into 8 ohm load/ 45 watts/ch. into 4 ohms/ 80 watts/ch. into 16 ohms
  • Power bandwidth: 2 Hz – 75 kHz within 1/2 db
  • Input impedance: 100Kohm single-ended, 200Kohm balanced
  • Input voltage for full output: 2.83V
  • Frequency response (1 watt): 1 Hz – 100 kHz within 3 dB
  • Intermodulation Distortion: .05% @ full power
  • THD: typically under .5% with proper setup.
  • 20 Hz square wave tilt: unmeasurable
  • Phase shift: less than 1 degree @ 20 kHz
  • Power supply storage: 140 Joules/chassis
  • Input impedance: 100K single-ended, 200K balanced
  • Output section risetime: 600 V/micro-second
  • Output Impedance: ~4.1 Ohms
  • Feedback: 1 db
  • Power consumption: 300 watts/chassis
  • Tube complement: 8 6AS7/channel and 4 6SN7s
  • Weight: 30 lbs./chassis
  • Dimensions: 17″ wide x 13″ deep x 8″ high

Atma-Sphere MA-1 MK3.1 amplifier

Atma-Sphere MA-1 MK3.1 amplifier is recipient of Golden Ear Award from The Absolute Sound in year 2000. The MA-1 has enjoyed an enviable reputation. Now the Mk.3.1 series builds on the advances of our decades-proven technology. An improved output section and enhanced driver circuit contribute to superior low level detail, smoother sound, wider bandwidth and AC power immunity. The new, rugged, non-magnetic chassis features classic looks with superior layout. Setup of the amplifier is simple with automatic bias. The controls and switches are ergonomic without sacrificing performance.

The MA-1 Mk.3.1 is easy to live with. It is easy on tubes and and tube failure is inconsequential. Despite its extreme performance, the MA-1 is known for remarkable ease of setup, ease of operation and day to day consistency. Atma-Sphere’s new custom wire, V-Cap Teflon coupling caps, custom resistors and the features below are why Atma-Sphere amplifiers are the best worldwide, regardless of cost.


  • Balanced Differential Design®
  • All triode
  • No tube matching
  • Class-A operation
  • Automatic bias
  • Patented Circlotronic® Output transformerless operation (OTL)
  • Handwired mono construction
  • Easily monostrapped for more power
  • Standby switch for long output tube life
  • Simple, reliable circuit –one stage of gain
  • XLR and RCA input connectors
  • V-Cap Teflon coupling capacitors- standard
  • Custom built wire and resistors
  • Precision components used throughout
  • “Star” ground circuit
  • Neo-classic chassis is available in custom finishes
  • Three-year warranty – One year on tubes


  • Caddock Resistor package $1100
  • Power Supply Boost (uses custom built filter caps for MA-2) $2400
  • Meter panel color options: brushed anodized gold, black or silver, no charge


  • 140 watts/channel into 8 ohm load/135 watts into 4 ohm load
  • Power bandwidth: 2 Hz – 100 kHz within 1/2 db
  • Frequency response (1 watt): 1 Hz – 200 kHz within 1/2 db
  • IM distortion: less than .05% at full power
  • THD: nominally less than 0.5% with proper setup
  • 20 Hz Square Wave Tilt: unmeasurable
  • Phase shift: less than 1 degree @ 20 kHz
  • Power supply storage: 600 Joules/chassis
  • Input impedance: 100K single-ended, 200K balanced
  • Output section risetime: 600V/micro-second
  • Output Impedance ~2.3 Ohms (power method standard measurement)
  • Power consumption: 500 watts/chassis
  • Tube complement: 14 6AS7s and 5 6SN7s per channel
  • Weight: 36 lbs./chassis
  • Dimensions 18″ L x 17″ W x 8.5″ H

Atma-Sphere Music Amplifier MA-2 MK 3.1

Atma-Sphere Music Amplifier MA-2 is winner of Reviewer’s Choice 2004 as well as two Golden Ear Awards by Harry Pearson and Jonathan Valin of The Absolute Sound. 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. 3.1, 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. 3.1 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.


  • 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


Custom finishes possible. Contact us for details.


  • 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 0.5%
  • 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

Atma-Sphere Music Amplifier MA-3

Atma-Sphere Music Amplifier MA-3is a project Atma-Sphere began in 1998 at the behest of one or its customers. It was 7 years in design; 15 chassis and 7 circuit designs were explored in depth. The idea behind the project is to build a larger version of Atma-Sphere amplifiers than the world has seen before, while at the same time keeping it easy to live with.

One of the biggest problems with amplifiers of this much power output is performance. Tube amplifiers are traditionally best sounding in low power embodiments and high power tube amplifiers often have such poor bandwidth that credulity is strained to call them high fidelity! Transistor amplifiers regardless of price retain the artifact that continues to identify them as transistor amplifiers to the casual listener, regardless of power or cost.

So there is clearly a dreadful need for an amplifier that can actually make serious power yet remain utterly musical. Fortunately, our OTL technology is well suited to the task since we are not limited by issues that plague conventional amplifier designs. At last it is possible to build a truly high power amplifier that is all-tube and has wide bandwidth at the same time. No transformer-coupled amplifier can produce 200, yet alone 400 watts and get it right at every audio frequency; the MA-3 makes 500 watts easily, without electronic artifacts: a high power amplifier that is actually musical.

The MA-3 has all of the features as our other models, plus a few not seen in any amplifier ever produced before. It is class A, all triode, and fully differential, with Atma-Sphere’s patented direct-coupled output circuit. There is only a single gain stage in the amp, so the signal path remains very direct, a feature unknown in amps of this class. Construction is point to point handwired with our custom wire.

What’s new are several features that make the amp very easy to own and operate: There is a built-in on-the-fly tube tester, allowing one to test (and if desired, match) the power tubes in circuit with ease. The output power can be varied, by turning output tubes banks on and off. One can operate the amp on 1/3, 2/3 or all of the output tubes. This saves on the life of tubes and is a useful tool for managing the heat output. Even at lower power levels, the MA-3 retains the innate musical character that defines it as state-of-the-art.

Bias and DC Offset functions are automated. Meters are supplied to monitor the tubes, output power and other features. The amplifier power supply has a built-in AC line processor that regulates the AC line. Line voltage has virtually no effect on the MA-3- it will make full power even if the line voltage is only 100 Volts.

Meters functions include: VU level, tube condition, Bias and DC Offset status and automatic AC line voltage condition. The amp is built on four chassis. The amp unit can be stacked on the power supply unit (as seen above) or operated side by side. Dual speaker posts are used for more flexible operation. Other features are standard per our other amplifiers:

  • Class A
  • All-triode
  • Fully differential operation (Balanced Differential Design®)
  • Single gain stage
  • Patented OTL output circuit
  • Zero feedback
  • Automatic Bias and DC Offset control- no controls to adjust
  • Regulated AC line voltage treatment built-in
  • Built-in tube tester- test tubes on-the-fly
  • Meters for DC Offset, output power, tube condition, AC power and AC regulator
  • Bank-switchable output level- 1/3 power, 2/3 power or full power
  • Balanced (XLR) and single-ended (RCA) inputs
  • Hardwired throughout with our custom wire
  • Dual speaker posts
  • High energy power supplies- custom built filter caps
  • Matched V-Cap Teflon® coupling caps
  • Custom built Caddock® resistors
  • Welded, ground, brushed and two-tone anodized chassis
  • Easy tube availability with long tube life- no tube matching!
  • Standby function


  • 500 watts/channel, 2-16 ohms
  • Bandwidth 1-100KHz within .5 db
  • IM distortion: 0.04% at full power
  • Input impedance 100K single-ended, 200K balanced, selectable to 600 ohms
  • Output section risetime 600V/microsecond
  • 1/4 Farad of power storage capacity per channel- the most of any production amplifier!.
  • The power supply chassis is 21″ wide, 34″ long and 12.5″ high. Weight: 152 lbs.
  • The amplifier chassis is 21″ wide, 31.5″ long and 15″ high. Weight: 80 lbs.

Atma-Sphere MP-1 Mk. III Preamplifier

Atma-Sphere MP-1 Mk. III preamplifier, recipient of Golden Ear and Reviewer’s Choice Awards, introduced in 1989, the MP-1 was the world’s first fully-differential balanced-line preamplifier. MP-1 is transformation in the world of preamplifiers. It easily outperforms passive volume controls (PVCs), transformer volume controls (TVCs) and conventional line stages. Atma-Sphere developed and controls the patents which allow for this breakthrough; no matter what type of preamplifier or volume control system you thought was the best in the past, the MP-1 is an easily audible improvement. The MP-1 doubles as a state of the art headphone power amplifier.

In 1989, the first MP-1 was the introduction of balanced line technology to the world of high end audio. It was the first all-tube preamplifier to offer an all-differential zero feedback package with a direct-coupled high current output capable of driving 600 ohm balanced lines. Even 200 foot interconnects are no problem! Back then it was breakthrough technology, and remains so today, as the MP-1 Mk. 3.1 has years of refinement, patents and awards. Our Circlotronic® technology has transparency unimaginable to those who have not heard it. Our patented direct- coupled output solves a major tube preamp problem: the output coupling capacitor. This capacitor has to be large enough to play bass, but large capacitors of any type can’t play the mids and highs so well. Getting rid of it is a breakthrough. Transistor preamps often use direct-coupling, but: they sound like transistors! Thus a lot of audiophiles have gone to using passive devices, thinking they have found the answer. This is only because they have not heard technology that works, and frankly, no-one could blame them since the MP-1 (and the MP-3) stand alone in the world of active preamps that work!. If you are not running an MP-1 or MP-3 passive controls may well be the next, albeit distant, best choice.

The MP-1 complements the design of our balanced-line amplifiers and works well with any amplifier with balanced inputs. Phono cartridges are naturally balanced sources; the MP-1 complements them as well. Audio is recorded in the balanced domain- now you can play it back that way too.

Balanced lines have been in use in the recording and broadcast industry for decades to eliminate interconnect cable issues. This is how high fidelity recordings existed before the exotic interconnect cable industry did (the high-end audio industry sort of re-invented the wheel, not knowing what was already out there…). The balanced line system is better because it is resistant to RF, hum, noise and cable differences. Long cables are easy too. This virtually eliminates the need for an exotic cable to achieve state of the art performance.

The MP-1′s capabilities, due to its patented direct-coupled output in an all-tube package, is unique. Our Balanced Differential Design® insures a minimal number of gain stages (three from phono input to high level output), low distortion, wide bandwidth and dynamic range: the State of the Art in preamplifiers.

“…the MP-1′s ability to bring me closer to the original musical event was head and shoulders above that of any preamp I’ve ever heard in my home system…I’ve always felt that the highest praise a reviewer can bestow upon a product are the three little words, “I’m buying it.” …What more can I say? Yes, I’m buying it.” -Steven Stone, STEREOPHILE, Dec.’93, Vol.16 No.12

“During my time with the MP-1 Mk III it worked flawlessly and easily proved itself the finest-sounding full-function preamp to grace my system to date. So in touch with the musical performance did it put me, so addictive was its clarity, that, for me, the MP-1 Mk III recalibrated my expectations for stereo reproduction. I urge caution if you plan to audition the MP-1 Mk III: You may not be able to walk away without it. But you can’t walk away with the one here — I’m keeping it.” …Tim Aucremann, Soundstage.


  • Balanced Differential Design®
  • Headphone compatible with a simple connector
  • XLR connectors for phono and aux
  • XLR output connections
  • Patented direct-coupled Circlotronic® output
  • Fully regulated supplies featuring our proprietory regulator
  • Zero feedback design throughout
  • Dual-mono construction
  • Differential passive phono equalization
  • Precision 24 position stepped volume control built from a Shallco® custom switch
  • Two tape monitors (tape functions use RCA’s)
  • Precision components used throughout
  • Total system phase switch
  • Teflon® custom coupling caps
  • “Star” grounding used throughout
  • Outboard power supply
  • Two-tone antique finish
  • Three-year warranty


  • NEW! Remote Volume Control $950.00
  • V-CAP Teflon coupling caps for phono $500 (replaces a set of polystyrene parts in the output of the phono section)
  • V-CAP Teflon caps throughout (includes the phono location above) $1500
  • Caddock resistor package $1700
  • Caddock volume control $2600
  • Low output MC stepup transformers (for cartidges under 0.2mV) $750
  • Damping package $600
  • Dual outputs $75.00
  • Alternate panel finishes available


  • Line stage bandwidth: .1 Hz – 400 kHz, +0 db, -3db (-0.5db @ 250KHz)
  • Line stage gain 14 db
  • Line stage input impedance 500K single-ended / 1M balanced
  • Line stage output 32 V into 600 ohms
  • Output impedance 30 ohms
  • Phono gain: ~60db
  • Phono bandwidth: .5 Hz – 100 kHz, -.5 db
  • Phono input impedance 47K- easily set with rear panel loading strip
  • RIAA accuracy: within .07 db
  • RIAA phono sensitivity: 0.15 mV
  • Phono section max output: 120 V p-p
  • Phono input overload: 250 mV
  • Power supply storage: 170 Joules
  • Tube complement: 8 12AT7s, 10 6SN7s
  • Dimensions: 17″ Wide (19″ panel width), ~12.5″ Deep, ~6″ High, 2 chassis
  • Weight ~45 lbs.