Audionet Stern Linestage and Heisenberg Monoblocks

Teutonic Masterpieces

Equipment report
Solid-state power amplifiers
Audionet Stern Linestage and Heisenberg Monoblocks

From Audionet’s beginnings in January 1994, Thomas Gessler’s goal has been simple: to create the finest amplifiers. As Audionet moves into its 26th year, Thomas will tell you that over the past quarter of a century, there have been no amplifiers on the market that measured better than his. Still, toward the end of 2013, shortly before Audionet’s 20th anniversary and just before the major team expansion of 2014, Thomas had formed the basis for what would become his “Lighthouse” project: the creation of new products that would be generally recognized and remembered as true milestones in the history of audio electronics.

This “Lighthouse” project would take an utterly unfettered approach, with no cost limits or production deadlines. The effort would require time, unconstrained thinking, and perhaps even more of a fresh approach than any work he and his team had undertaken to that point. 

Both the concept of naming these “Lighthouse” machines after famous scientists (and hence calling them the Scientist Series) and the idea of involving the highly accomplished German industrial designer Hartmut Esslinger, founder of the Frog Design Group and probably best known in the U.S. for his work with Apple, were the contributions of Audionet Branding & Marketing director Jan Geschke (Mercedes-Benz, Porsche, Dali, and Dynaudio). 

Jan reached out to Hartmut via a mutual friend, Dietmar Henneka, a famous Stuttgart-based freelance and automotive photographer. Once up to speed on what Thomas and the Audionet team had in mind, and excited by the thought of what he might be able to contribute, Hartmut committed to the project. In fact, the very reason he chose to work with Gessler and his team was because, in his own words, “Audionet is a fanatic company.” 

The Stern linestage (named for Otto Stern, a German American and 1943 Nobel laureate in physics) and the Heisenberg monoblocks (named for Werner Karl Heisenberg, a German theoretical physicist and one of the key pioneers of quantum mechanics) are exquisitely executed examples of industrial engineering—so much so, in fact, that the Stern has earned a place in the Smithsonian National Gallery. Unquestionably, its use of a unique, patented Floating Pane Design, which provides optimal resistance against microphonic effects and maximizes thermal stability, contributes significantly to its eye-catching look. Essentially, these machines do not have a fixed body. They are, instead, made up of six massive floating panes, which do not touch each other and are resonance-optimized by pads on an aluminum frame.

Much like the previously reviewed MAX monoblocks and PRE G2 linestage (Issue 279), but with everything taken to an even greater extreme, these machines exhibit great attention to overall design by magnetically and capacitively optimizing the circuit and eschewing the use of any ferro-magnetic materials. All the mounts and bolts of assembles, such as those used for the transformers, are made of stainless steel, and the circuitry and power supply layout is dual mono to maximize channel separation. Considerable attention was paid to board and circuit layout to maximize air flow and afford optimum cooling, helping to provide stable quiescent currents throughout the entire chassis. Finally, all analog circuits are galvanically separated using opto-couplers.

 With Stern, both input and output sections, as well as the volume control, are implemented using enhanced discrete Audionet operational amplifier modules, which include advanced mica capacitors. The volume control uses a double-ball-bearing axis, with magnetic ratchet and optical sensing, and is controlled by electronic switches and a real-time-linearized precision-resistor network.