The home of High End OTL tube amplifiers
Handmade in the USA since 1976

 An insight into how we build our award-winning OTL amplifier
"Making the Atma-Sphere M-60"

Atma-Sphere S-30, OTL valve music amplifier


The S-30 is the unchallenged state-of-the-art in low power vacuum tube amplifiers. With its simplicity of operation, small footprint, and all the features of our larger amps, the S-30 represents the high-water mark of compact OTL design.

Atma-Sphere M-60


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.

Atma-Sphere MA-1


The Atma Sphere MA-1 is extraordinary in every way. Despite its extreme performance, the MA-1 is known for remarkable ease of setup, ease of operation, day-to-day consistency and of course extreme musicality. A masterpiece! 

Atma-Sphere MA-2


Introduced in 1990, the MA-2 was the largest production triode amplifier and the largest production OTL in the world for nearly 12 years. In that time it set the bar for quality that has yet to be surpassed. The Atma-Sphere MA-2 is one of the finest amplifiers made anywhere in the world regardless of price. Not only is it one of the most powerful production Output Transformerless amps available, it is also the most reliable!

Atma-Sphere MA-3


The Atma-Sphere MA-3 amplifier 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 world!

Our Hi-End Tube Preamplifiers

UV-1, MP-1 and MP-3

Atma-Sphere UV-1


The UltraViolet preamplifier is based on a circuit that we have used for many years, but not marketed before. Over a period of decades, the circuit has seen a lot of refinement. It is a simple circuit (and obviously a complete departure from our other products), based on a very capable and refined 6SN7-based line section with a simple phono section based on 12AT7s. We have seen this preamp best preamps costing up to five times more; when we say 'refined', we mean it!

Atma Sphere MP-3


The AtmaSphere MP-3 extracts more ambient information with greater image specificity, bass definition and dynamic range than any single-ended preamplifier, owing to its patented direct-coupled output. Furthermore, MP-3 preamplifier perfectly complements the balanced design of our amplifiers or any balanced power amplifier. The patented innovations, developed specifically for this preamplifier, make the MP-3 one of the best preamps made today.

Atma-Sphere MP-1


The first balanced, fully-differential preamp ever made, with innovations that were breakthroughs in '89 and remain so today. MP-1 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 decades of refinement, patents and awards, the MP-1 is a paragon of the audio world. 


Atma-Sphere MA-1

Golden Ear Award

The MA-1 shines as an example of why our amplifiers have won so many awards over the years.

Atma Sphere Awards

About us

Atma-Sphere is a small company in Saint Paul, MN that has been making world-class vacuum tube music amplifiers since 1976.  We are known for our unique approach to circuit design, resulting in multiple patents and the creation of the first, truly reliable Output TransformerLess (OTL) amplifiers. We made the first balanced-line products in the world of high-end audio, including the MP-1, which was the world's first balanced-line preamp. All of our amps and preamps are hand-crafted and made-to-order according to each customer's needs. All of our components are hand-selected, and often custom-manufactured especially for us, right down to the wire we use. The resulting products are unique in the world with an unmatched capacity to reproduce music with intrinsic reliability. 


1742 Selby Avenue
St. Paul, MN 55104


Tel : +1 651-690-2246


French version