The Leslie Model 30A
This model called the "Vibratone" was the first Leslie Speaker that was made for the Hammond Organ in 1938 by Donald Leslie of his newly formed company called Electro Music. This was a single speed model (fast & off) that had no provision for controlling the rotors from the organ console (no half-moon switch) instead, it had 2 toggle switches mounted on the left side of the cabinet and you had to have the cabinet close to the organ. You had 1 switch that turned the upper horn rotor on or off, and another switch that turned the lower bass rotor on or off.
The amplifier contain in this model had a power output of 35 watts and contained (4) 6L6 tubes in the output stage. The upper horn rotor unlike later models was made out of paper mache' and spoke through the top of the cabinet rather than through louvers on the front and sides. (notice the brown bottle of oil which was the original Leslie oil for the rotor bearings) This early model Leslie used a 15 inch "Electro-Dynamic" speaker for the bass rotor as well as the compression driver for the horns. What this means is that BOTH speakers did not have a permanent magnet, like speakers of today have, but a large coil of wire which was used as an electro-magnet. The way the coil was wired it acted as a filter choke for the amplifier's power supply.
Below is an original schematic of the amplifier
The tubes that were used in this first release model were 2-5Z3, 4-6L6, and 2-6P5. This Leslie tone cabinet at the time was used with the Hammond Model "A", "B", and "BC".
There aren't many of these baby's around, but they are certainly worth $$$ if you find one not to mention they sound great especially the low end from having a tall cabinet.