These Leslie tone cabinets are designed for single-channel organs whose pedal range extends down into the lower frequencies. The sound is "separated" with the highs reproduced by a horn rotor and the lows reproduced by a bass rotor. Both the horn and bass rotors can be operated at two speeds : Fast (Tremolo) or Slow (Chorale). These models also features a traditional tube amplifier for the "warm tube" sound.

The model 147A, which shares the same cabinet design as the 122A, is recommended for single-channel organs with self-contained speaker systems, such as Hammond Organ model A-100 and spinet models such as M, M-2, M-100 and L-100.