Nemesis was a design of Jean Hiraga, at the time Editor-in-Chief of the French L'Audiophile. It was published in issues 34 and 35 in spring 1985. L'Audiophile was a very high-end audio diy journal, strongly oriented to the Japanese audio diy scene.
This is the circuit schematic (c) L'Audiophile
The inside picture on the left shows the very minimal PC board, holding the few passive components, with the Exicon lateral MOSFET ECF10N16 on the heatsink. The original MOSFET (a 2SK135) has been obsolete for many years, but Exicon (available through Profusion Plc in the UK) have been making very good replacements with often better specs than the originals.
On the right you can see the linear post-regulator with LT1085, and on the real right under the aluminum bracket hides the Hypex 180W SMPS supplying the 40VDC for both amps. The original Nemesis had a linear supply with an EI mains transformer and over 100.000uF of supply caps per channel. Still, because of the output transformer, it was very difficult to get rid of hum that would be coupled from the mains transformer to the output transformer. A large chassis for physical separation of the transformers as well as painstaking rotation of one with respect to the other would minimize hum, but I did not find it satisfying. The solution with the SMPS followed by a simple linear regulator made the amp very quiet.
More to follow
The output transformers are very large and heavy for the output power (some 10-12W), because they carry the supply current for the output stage which is about 1A. To avoid saturation, the output transformer needs an air gap in the core. But that air gap drops the inductance so now you need more windings to compensate for that, and in the end you end up with a large transformer.
