When you’re looking to build an amp on a budget, one of the hardest pills to swallow is the cost of a suitable power transformer. Wouldn’t it be nice if there was a cheap alternative you could pull from the scrap heap?
Like most things in life, I never want one of anything. One computer, one guitar, one motorcycle… No, I want that British chime. I want that pentodey grind. I want a Vox. So I built one!
Projects tend to grow. Evolve. Transform. Take on a life of their own. Some of them find bizarre ways of staying alive, or coming back to life after you think they’re long dead. Sometimes they start as one thing, become something else, and come around full circle to be what you started with in the first place. This is one of those “living” projects that just keeps on changing.
One day I dug through my pile of salvaged transformers and came across an interesting little piece. It’s an inter-stage percussion transformer from a Hammond M3 organ, part A0-24113-0. It is listed as T5 in the AO67, M100, and other circuits. It’s about 1.5″ x 2″, not very big. Hammond used it as an inter-stage signal transformer that also coupled in a low-impedance signal on a third winding. Everyone who has ever scrapped a Hammond organ has one of these sitting around, so there are plenty of them out there for cheap or free. I fed it a little AC...