So the worship leader of our church and I were looking for some stuff in a thrift shop today. They had about 5 organs there, but most were SS. HOWEVER we did manage to find one that is TOOB. It's a Gulbransen APF-4. Picked it up for $45!
1x12AX7
2xEL84
1xEZ81
The thing works like a charm. The tubes are original from Holland. Even the rotary speaker works. Sounds pretty good, although the E cap cans almost surely need to be replaced. He wants me to add an FX loop to it. I can't find a schem, but I'm sure the design is pretty simple. Maybe a standard gain stage and cathodyne PI?
From what I read, the PT supplies voltages to other parts of the organ as well. Not just the amp. The lower notes only sound alright through the rotary speaker. One of them though makes a weird R2D2/Skrillex noise when you step on it.
