The Earl of Whirl--Capturing the motion and emotion of the Leslie speaker cabinet.

The Earl of Whirl
Capturing the motion and emotion of the Leslie speaker cabinet.

By Brian Knave

Can’t fit a Hammond B-3 into your home studio? That didn’t stop the author, who recorded organist Dan Eisenberg by putting the Leslie in the studio (see photo on p. 126) and the B-3 in the backyard (click for pop-up).

Just as Helen of Troy’s beauty launched a thousand ships, the sound of the Leslie “tone” cabinet has launched a thousand emulations. But even the best of them—and there are some good ones—pale in comparison to the real thing. What makes the Leslie sound so compelling? In a word, motion. The sound from a Leslie cabinet moves not only outward but also in a circular direction around a pivot—sort of like the sparks from a fireworks pinwheel. As the sound spins out at varying speeds from the Leslie’s rotating components, the listener hears a complex blend of Doppler effects (including frequency and amplitude modulation), phase shifting, frequency masking, and ambient reverberation. That highly animated sound is further colored by the Leslie’s tube-driven amplifier, which often is driven to distortion.

It’s no wonder most musicians and producers prefer recording the real thing to using an emulation. But is it really possible to accurately capture the magical sonic phenomenon you encounter in a nightclub while listening to the likes of a Jimmy Smith, Joey DeFrancesco, or Larry Goldings (to name just a few masters of the classic Hammond B-3/Leslie combination)? No, not really. No matter how well you record a Leslie, the experience of being in the room with the Earl of Whirl is simply not going to translate fully through a pair of stationary speakers. But take heart: many of the elements that make up the Leslie sound can be documented faithfully in the recording studio.

Brick House

FIG. 1: This conceptual diagram shows the basic inner workings of a Leslie. Note that one of the treble horns produces no sound.

Of the many Leslie models that were built, the most popular are the 145, 147, and 122, which I will focus on. Those models share several features, including a three-compartment cabinet design. The top compartment houses a rotating treble horn with identical-looking bells that face opposite directions from each other. Note that only one of the bells channels sound; the other is a dummy that acts as a counterbalance so the assembly spins smoothly without wobbling. Also worth noting is that the horn assembly is mounted off-center in the cabinet—an important detail in some miking setups.

The cabinet’s closed middle compartment contains the high- and low-frequency drivers and 800 Hz passive crossover. The treble unit is a 3/4-inch Jensen compression driver (the kind used in P.A. speakers) connected to a vertical tube that feeds into the rotating horn assembly. Bass frequencies are handled by a 15-inch speaker that fires downward into a rotating wooden drum located in the cabinet’s lower compartment (see Fig. 1). The lower compartment also houses the Leslie’s 40-watt monophonic tube amplifier.

The treble horn and wooden drum are turned by rotors driven by two dual-speed motors, letting the player choose between slow and fast rotation speeds—for chorus and tremolo, respectively—independently for each element. Interestingly, the wooden drum turns clockwise and the treble horn counterclockwise. In addition, the two units’ rotation speeds, though roughly the same at slow and fast settings, differ during ramp-up and ramp-down times because of the wooden drum’s greater mass—yet another factor that can deepen the complexity of the sonic stew.

Reprinted with permission from

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