“Launched at Munich High End May 2023, the Ianus Protos Integrated amplifier uses TriodeFet technology and has features that make it unique in the already innovative Ianus range.“ - Stavros Danos, Designer
 
Single Ended Single Stage?
 
The Ianus Protos integrated amplifier and its amplifier siblings in the Ianus range, uses TriodeFet technology, and it is based on it’s bigger brother, the Aperio.
 
Just like the amplifier based in,and contrary to the bigger Geminae model, the Protos is using the TriodeFet active element in a very different topology, as this is a Single Ended design It goes a step beyond to be the only integrated amplifier which is Single Stage as well. One stage from input to output posts.
 
The Design Concept
 
Like the bigger Essentia model, incredibly, there is no driver stage and no input stage! However this is not just an amplifier but a complete integrated amplifier.That means that from the input to the speaker outputs, there is only one stage of amplification.
 
This extremely simple topology we feel is a breakthrough in amplifier design, and is an elusive design goal for many, including our lab. This feat was only possible to execute after the breakthrough of our TriodeFet technology, and now we are finally able to use an active element that has the needed specifications for the purpose: Extremely high linearity, high voltage gain, high current gain and very high input impedance.
 
The Aperio and Protos integrated amplifiers use a common circuit core but with many differences in PSU design and output stage.
 
‘The Protos’ means ‘The First’. The Protos started as an exercise as to how small and simple we can make an amplifier out of lessons learned developing our bigger TriodeFet amplifiers. We strongly believe this is smallest sample of the technology, as the Minimum Complexity principles dictate how simple things can be designed and implemented. The Protos is indeed the First, and the smallest offspring of our TriodeFet technology.
 
The volume control is implemented by  R2R relay-switched resistor array , instead of the complex (TVC) multitap input transformer used in our bigger models.
 
Practically maintenance free
 
The TriodeFet technology, in contrast to a SET amplifier design that is using big output tubes, is essentially maintenance free as the internal tubes used for curve creation are rated at more than 10,000 hours lifespan. Its unique single stage nature means that it is as sonically transparent as it can get. The amplifier power delivery is 20W (8ohm) full class A.
 
Triode or solid state?
 
Neither. TriodeFet technology does not sound like a hybrid, tube or solid state amplifier. It sounds how an ideal tube amplifier should sound..
 
The triode-like transfer curves of the TriodeFet means the Ianus Protos like the bigger brother Aperio and Essentia, sounds very much like the very best Single Ended tube amplifier. A superb midrange and treble, accurate timbre and the huge soundstage we expect from big bottle tube amplification.