QUESTION:  Will a 147 amp work in a 122?

ANSWER:  A 122 cabinet is identical to a 147 cabinet. Both use the same speaker for bass and the same treble driver for highs as well as the standard Leslie 800 HZ crossover. Two speed models are the 122, 147, 145, 251 and a few other obscure models. Single speed versions of the 147 are the older 47 and the shortie cabinet 45. The single speed versions of a 122, which is 40 watts, are the single speed 22H, also 40 watts, and the 21H with either  20 or 30 watt amplifier. The 20 watt amplifier runs four 6V6 output tubes. The larger 30 watt amplifier runs four 6L6 tubes. The newer 22H running the 40 watt amplifier with a pair of 6550 output tubes. The difference is in the amplifiers. If you have an organ that is set up with a kit for a 122 including the front rail mounted Choral/Tremolo half moon switch then the answer is no, they are not interchangeable. If you have an organ with no kit then you'll eventually have to add one and you could add the 147 kit if that is the amp in your Leslie. If your organ is set up for a 45, 47 145 or 147 Leslie then of course a 147 amp will work. Both work on the standard Hammond / Leslie 5 or 6 pin cable but the wiring is totally different. The amps are NOT interchangeable. Sparks will fly if you try using a 147 amp where there should be a 122 amp and vice-versa. The main difference is the 122 uses low voltage; up to 90 volts DC to switch speeds. A 147 uses high line voltage AC 110 volts for speed switching. There is much more to the difference. If you want a more in depth description, just email me. I have been restoring, fixing, rebuilding and modifying Hammond organs and Leslie speakers for over 30 years. I knew Don Leslie personally until his death several years ago. He lived about 15 miles from me in Altadena California. I know all about hot rodding organs and Leslie speakers and how to convert useless Leslies such as thefour channel  205/610 family into either a 122 or a 147 for use on any Hammond organ. I'm sort of the guru of the mods in Southern California for bottom rotor only Leslies like the 25, 120, 125, 820, 825 and others by simply adding the top horn and the associated components to go with it. If you need any more information just email me back with your specific question. You might want to print this out for future reference. This kind of information is not always easy to find on the internet.