What are the sonic characteristics of these power supplies. It apperars Krell, Lexicon, Anthem, ATI & others, use Torroids. Is Denon comprimising sound quality, using E-core xformers, while doing too many things, like dual 5.1 systems, MultiEQ...?
There is no dramatic difference between a toroidal transformer and a conventional transformer. Both work in same way. Basically the difference is just the mechanical form of the transformer.
The main difference is that the traditional transformer and toroidal transformer are wound to a different form of transformer core. The traditonal tranformer use typically so called "E"-cores which are made of stacks of iron. Toroidal transformer used a toroidal transformer core (shape of "O"). a torrid core provides a closed magnetic circuit and doesn't loose any flux into free space as it would if the same core was in the shape of a rod. lost flux is lost energy, therefore, a torrid will provide higher inductance, tighter coupling , higher efficiency, and higher Q, and on and on. The whole concept is to physically concentrate the flux where it is needed. Also, because the flux is concentrated in the core, components that would normally be affected by being in the proximity of an inductor/transformer, can be mounted closer to a torrid, and a torrid will generally be smaller than an inductor or transformer using more conventional core shapes.
In principle a perfect toroidal winding has no external magnetic field, and in practice toroidal transformers do have lower external fields, but transformer designers tend to design toroids to run closer to saturation, which increases the external field, largely eliminating the advantage.
Toroids are popular in hi-fi amplifiers because they allows claims about low external field, and - much more important - because the weight of the wound toroidal transformer is lower than than equivalent conventional transformer.
The "squashed" profile of the toroidal transformer also gives it more surface area per unit VA than a conventional transformer, so it dissipate more heat per unit temperature rise, which the designers exploit by running them at higher current density.
In all practical purposes the toroid is more space efficient and can possibly generate less external fields than a typical E-core. We will have to see how well the 5805 analog designers managed this problem. Knowing Denon, its likely NOT an issue!
