Atma-Sphere MP-1 Mk II Preamplifier with Phonostage

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  • Regular price $3,499.00

Atma-Sphere MP-1 Mk II Preamplifier with Phonostage & Solid-State Regulator

Serial number: 310. Unit is new old stock so does not carry a factory warranty but we will extend our own 90-day warranty on this unit. It's in excellent condition and tubes test new. 

In 1989, the first MP-1 introduced balanced line technology to the world of high end audio. It was the first balanced, fully-differential preamp ever made, with innovations that were breakthroughs at the time and remain so today. With decades of refinement, patents and awards, the MP-1 is a paragon of the audio world.

If the MP-1 is something you've not encountered before, it is unique in the world of preamplifiers. It easily outperforms conventional line stages and any passive or transformer volume control on account of its patented direct-coupled output which allows for greater transparency while also preventing coloration from interconnect cables. With only three stages of gain in the entire preamp (including the phono section), the Balanced Differential Design® is an elegant signal path that assures low distortion, wide bandwidth and dynamic range. 

Atma-Sphere's patent solves a major preamp problem: the output coupling capacitor of the preamp. This capacitor has to be large to play bass (especially driving solid state amps), but large capacitors can't play the mids and highs properly no matter how good the capacitor is. Getting rid of it is a transparency and bandwidth breakthrough. Until we created our patent, there really was no way to do this reliably with vacuum tubes. Transistor preamps often use direct-coupling, but sound like transistors! Some audiophiles have gone to using passive devices, thinking they have found the answer. This is only because they have not heard technology that works. The MP-1 and the MP-3 stand alone in the world of active preamps that work!

The MP-1 is fully differential and balanced because the Balanced Line system eliminates interconnect cable coloration, which is why the recording and broadcast industry has used it for the last 55 years. This is why high fidelity recordings existed before exotic (high end audio) cables did! The balanced line system is better as it resists interference and noise, as well as cable artifacts (sound changes with different cables) and cable length. This eliminates the need for an exotic cable (and its cost) to achieve state of the art performance.

The MP-1 nicely complements our balanced-line amplifiers, but works well with any amplifier. Phono cartridges are naturally balanced sources; since audio is recorded in the balanced domain, now you can play it back that way, too; this elimintates the artifact of the tone arm interconnect cable. The MP-1 works well with very low output moving coil cartridges (less than 0.2mV) and is a state of the art headphone power amplifier. 


  • Balanced Differential Design®
  • Robust output that can drive 32 ohm headphones
  • XLR connectors for phono and aux (paralleled RCA inputs optional)
  • Dual XLR output connections (RCA outputs optional)
  • Patented direct-coupled Circlotronic® output
  • Fully regulated supplies featuring proprietory circuitry
  • Zero feedback design
  • 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
  • Low-noise "star" grounding topology
  • Power supply isolated in seconds chassis
  • headphone compatible with a simple connector
  • optional RCA input and output connections available
  • other options: click on 'Order' above
  • Three-year general coverage warranty with one year warranty on output tubes


Line stage frequency response: .1 Hz - 400 KHz, +0 dB, -3dB ( -0.5 dB @ 250 KHz )
Line stage gain:12 dB
Line stage input impedance: 100 K Ω single-ended / 200 K Ω balanced
Line stage output: 32 V into 600 Ω
Output impedance: 30 Ω
Phono Stage (note, these specifications are from the Mk 3.3 which has an improved phono stage, so these are for general reference only)
Input impedance: 47 K Ω, adjustable with rear panel loading strip
Input overload: 300 mV
Max output (at clipping ): 120 V peak-to-peak
Gain: > 66 dB
Phono bandwidth: .5 Hz - 100 KHz, -.5 dB
RIAA accuracy: Within .07 dB
RIAA phono sensitivity: (for 0.5 V @ 1 KHz ) 0.15 mV
Power supply storage: 170 Joules
Tube complement: 10 x 12AT7 (phono section), 6 x 6SN7 (line section)
Dimensions (per chassis): 13" deep x 17" wide x 5.5" tall ( 33 x 43 x 14 cm )
Faceplate dimensions: (standard 3U rack, sans mounts ) 19" wide x 6" tall ( 48 x 15 cm )
Weight (per chassis): 42 lb (19 kg)


Upscale Audio 90-Day Warranty