This is the photo history of a complete redesign/conversion of a Heathkit AA-151 to a full triode circuit. Only the original chassis and transformers were used in this completely designed amplifier. The new amp uses 12AX7’s with EL-84 fixed bias outputs with a regulated power supply and ultra low noise phono preamp.
More progress updates soon – Completion ETA March 6, 2015
Before Shots:
Before Top: Stock (as received)…
Before Bottom: Stock (as received)…
Modification Progress Shots:
After Photo 1 – Chassis stripped down. All components to be reused, including the chassis, switches and controls were ultrasonically cleaned – ready for some serious mods.
After Photo 2 – Chassis components remounted, ready for wiring.
After Photo 3 – Current status: Transformers mounted — with 70% of component wiring completed. Wiring-up the transformers and the phono stage is next… those components are still in the bags.
Stay tuned for updates of the finished amplifier with performance specs and a Youtube video of how it performs.