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@ montesquieu  yes , the informations are from Silvio , this is the full text 👇

Some technical information regarding the different versions of the products (both the Model 5 and the Model 88 followed about the same path).

The first and second versions are very close in circuits and components – the main differences are on the way they are assembled, with a great evolution on the second regarding printed circuit boards and wiring (although most of the component directly connected to the tubes still, even today, soldered directly to the sockets).

In the third generation we changed the main transformer (from EI to Toroidal), something that improved the general dynamic and reduced the noise of the amplifier. We have also changed several components, as coupling capacitors, main audio resistors, connectors, etc. and have improved the power supply circuit.

With the introduction of the Maggiore amplifiers in 2011 we decided to make an special edition of the Model 5 specifically to work with it during the 2011’s show (we didn’t have at that time the Maggiore L50 preamplifier). In this case the main changes are on the components – special resistors, capacitors and wiring that match the ones carefully selected for the Maggiore line. The result was so good that we decided to make also an special edition for the Model 88 with the same concept. So, both Model 5 SE as the Model 88 SE are special editions of the third generation, with main differences on the components used.

The fourth generation follows the same concepts of the SE products (special components) with some additional changes on the audio and power supply circuits and an evolution on the output transformers. But maybe the biggest change in performance was the introduction of the use of special coupling capacitors that were developed by Jupiter condensers with our guidance – a project that took us two years of a very close partnership. At some point is very hard to define which parts are better per se but these specific components were developed having as reference both the Model 5 and Model 88 so I am sure we achieved the best possible performance for these specific products.

I’m now finalizing our fifth generation of these products, with major changes on the power supplies circuits (including totally different Power Transformers) and on the chassis of the preamplifiers, as we are also introducing our phono preamplifier (will be the “Model 9”) that can be “stacked” with these new Model 5. Maybe I should here explain a little bit about our philosophy regarding the power supplies…

I have to say that Both the Model 5 as the Model 88 work without any feedback on their audio circuits, something that is really much harder to implement with low noise and thermal stability but that, at the end, allow us to achieve a unmatched performance. But I would like to remember that what we call “audio circuit” is only a kind of “control” path for what, at the end, really “moves" our speakers drivers – the power supply current. So, it’s fundamental that this path also have all the care we normally take on the audio circuit regarding instantaneous and dynamic performance. In our case, all our power supplies has no regulation at all, something that could be considered as a kind of feedback (a very strong one, by the way). This is a really rare concept (I use the word "rare” but I don’t know any other company that uses it), probably because most of our “formal” Engineer education is directed to think about tensions (not currents – although everything are, at the end, moved by it) and looks as pretty clever to keep a fixed tension on the power supplies at any cost (even the audio performance, in our thoughts!).

Besides it we work with a minimum of capacitance on our power supplies (1000 times less when compared with some manufacturers), another concept that makes our power supplies much faster than the usual ones.

On the fifth generation of our products we have completely redesigned power supplies that now are even better, faster and with lower noise figures than the original ones. I believe this was our biggest change ever – the result of these new circuits are simple incredible .

Best regards,

Silvio

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