Our Ianus Series amplifiers is the showcase of our unique TriodeFet technology

After years of developing and refining our technologies we are proud to introduce the TriodeFet technology, and our Series of amplifiers that implements this truly innovative technology. The Ianus Series is promising to offer a final answer to the tri-lemma of: Tube vs Solid State vs Hybrid battle.

Our technology is neither a hybrid topology (in the usual sense of a tube-driving-solid state stage type), nor a solid state-driving-tube kind of stage. Note: Usually a hybrid topology is implemented as either a tube voltage gain stage-driving a transistor output stage/current buffer, or in some cases, as a solid state voltage gain driving a tube power stage.

The TriodeFet is not a Hybrid technology but a rather new way of using hollow and solid state devices.

A bit of history

We developed an early version of this technology in 2012, and launched our first design using the TriodeFet – the Ianus monoblock. After 7 years of rethinking how we could further refine and retune the system, we developed the second generation of the TriodeFet technology. Left is the Ianus (Mk1) monoblock amplifiers, circa 2013. These amplifiers were based on Generation 1 TriodeFet technology.

In General

Fets – Field Effect transistors used in many audio amplifiers, present the following characteristic transfer curves.

Typical Mosfet transfer curves

Characteristic transfer curves of a typical triode.

Triodes are probably the most linear active element engineers have ever invented. Their linearity is unmatched by any silicon based active element. However, the triode is a high-output impedance, high voltage/low current device, making the use of impedance matching transformers mandatory when driving low impedance loads – such as our loudspeakers. In a hybrid design, a tube will usually provide voltage gain, and a transistor stage will act as current buffer to the low impedance load (speaker). However the problem arises when you try to implement circuits that are designed to be only using tubes together with circuits designed to be only using transistors. For each of the voltage and current stage, regardless of being tube or solid state, the transfer curves of each active element will dictate the distortion characteristics of each stage (voltage and current). Not only in level, but also (especially so) in harmonic distribution.

So… What if we had a low voltage/high current active device, which had the linearity of a triode and at same time would be able to source enough current to drive low impedance loads directly?

Enter the TriodeFet.

What is a TriodeFet

The TriodeFet, can be seen as a three terminal active element, just like a Mosfet or a triode. The real breakthrough is that its transfer curves are identical of a true high quality triode, with the only differentiator from a true triode is that, the Y-axis (current) is in scaled in Amperes and not milliamperes. What this means, is that you can design circuits that were never before possible either by using tubes or transistors. This new active element can be used to develop simple, very linear circuits, which are stable down to very low impedances, while the TriodeFet’s inherent linearity is making the use of the problematic negative feedback redundant.

Generation 1 TriodeFet transfer curves

Generation 2 TriodeFet transfer curves

By using the Triodefet device as output active element, we can make full use of its triode like transfer curves, and transistor-like low voltage/high-current operation, and come up with very simple and straight-forward designs that have very high linearity, benefiting from the inherent linearity of the TriodeFet. This new active element can be used in very high bandwidth circuits, with high degree of linearity, without the use of global of local feedback, or use of other degeneration techniques etc.

The Ianus Series

After we finalized our second Generation of TriodeFet technology, we felt it was time to re-launch the Ianus name, under a Series of designs using the newest developments. Ianus is the two-faced Roman god. It symbolizes the duality of the nature of the TriodeFet. At the same time, the two-faced god gazes in opposite directions, symbolizing the past and present. We felt that this name symbolism is completely appropriate for this project. Our first design to be released is our flagship of the Series, the Geminae. It’s smaller brother the Essentia will follow in Q4 2020.