Technical notes on transformers



I would like to spend a few words to explain how we build the transformers used in our SUT units. I think that skilfulness is an advertising tool when it is rational and clever and most of all when it is used for the sake of obtaining electrical and musical performances. That is why we don’t keep the techniques we use a secret; indeed, I am proud of them.


My moving coil transformers are wound on a core made of MUMETALL with a large U-I shape. The nickel content of this high-permeability alloy is around 80%. I prefer the use of nickel over amorphous materials, which often tend to give a sound that is too analytical, in my PERSONAL judgment. The U-I shaped Clinamen cores are used by very few manufacturers (the E-I shape is usually used). They allow a PERFECTLY BALANCED assembly of the coiling, to the advantage of the primary/secondary coupling that reflects into an excellent linearity of response and control of parasite parameters. Indeed, the coils are wound not on one but two reels, each inserted on each vertical element of the ‘U’. Primary and secondary windings are interspersed for the purpose of increasing their coupling and improve the dispersed inductance. The high magnetic permeability of the alloy used (initial permeability greater than 15,000) together with the large sections of the nucleus used allows to obtain the necessary inductance with few turns; this helps to contain the dispersed inductance (proportionally to the square of the turns ratio). The loss of insertion is very high, due to the low resistance of the windings. Also, the primary inductance is very high in order to ensure an extremely linear response in width and in phase up to 10 Hz. Finally, the bandwidth is free from resonances within the audio band.


The dimensions (and consequent the volume) of the cores I use are two:

  • 12.5 sq cm for the transformers of the SUT "Triple Gain"
  • 28.5 sq cm for the transformers of the group "El Misti"

The " El Misti " line is at present the top of the range; indeed, provided that we don’t go over certain limits, greater cores allow to have low insertion losses and dispersed inductance, which result in greater dynamics and listening resolution. Nevertheless I’d like to highlight that even the 12.5 sq cm volume of the core in the ‘Triple Gain’ is a value hardly achieved in our competitors’ offers.


Lastly, towards the end of 2024 we will offer a new line, top of the range, with a nucleus equal in volume to the ‘El Misti’, but made of VACOPERM rather than Mumetall. This alloy, with an even greater permeability than Mumetall, allows us to push to absolute levels the performances of the Clinamen SUT units.