The ARMADA SET amplifier project
The ARMADA project was a joint project between Harvey “Gizmo” Rosenburg (architect) Lundahl Transformers (hardware supplier) and Jim Dowdy (solder slinger and advisor) started in the last century. Due to the early death of Harvey “Gizmo” Rosenburg, the Armada project was never completed. (One may question if a project like this will ever be completed, but that is a different issue).
Below please find some schematics and comments provided by Jim Dowdy, solder slinger and friend of Dr Gizmo. CAD drawings by Randolph Carter, IDSA.
- The AV20 + PX25 Interstage transformer coupled Armada (bottom part) is the more “musical ” of the group to me (Jim).
- The AV20 + PX25 L-C coupled Armada ( top part) is a bit cleaner and quicker sounding. I am sure that some will prefer it over the above.
- The third (L-C coupled) Armada version utilizes 1/2 of a 6SN7 or a 6J5 in liu of the AV20 front end. I have not built this version, but the schematic is included due to the difficulty in locating AVVT AV20s.
The design of the power supply units is left to the reader. Harvey “Gizmo” Rosenburg preferred using tube regulated supplies, but this is a matter of taste. As a transformer manufacturer, I (Per Lundahl) think that the hybrid power supply suggested by Andrea Cuioffoli is a good solution that combines tube characteristics with efficient transformer utilization.