Capturing the Leslie speaker cabinet.
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Two AKG C 460 microphones capture a stereo image of Eisenberg’s Leslie model 122 while an AKG C 414 B/ULS brings in the lows (click for pop-up).

These and other construction details can be critical to the recording engineer because Leslie owners tend to modify their cabinets in various ways. Organ players who kick bass, for example, often don’t want chorus or tremolo on the low notes, so they might disable the motor that turns the wooden drum. Other players, for whatever reason, sometimes disable the top motor. Obviously, in either case, the recording engineer who is unaware of the modification is at a disadvantage. If the top motor is disabled, for example, the engineer needs to manually align the sound-producing horn with the mic.

Other Leslie mods include mechanically linking the top and bottom rotors so that they turn at the same speed (this gives a more dramatic Leslie sound); switching out the power amp for a more powerful one or disabling it and using an external combo preamp; using different treble and bass drivers (typically because the stock ones were blown); installing a different crossover; or even bi-amping the treble and bass drivers. Although none of these modifications should influence the recording as much as disabling a motor, any will alter the sound and therefore may also affect how you record the Leslie.

You may encounter numerous other original Leslie models, including the older models 45, 47, and 22 (which are identical to the 145, 147, and 122 except that they have single-speed rather than dual-speed rotors). Other original Leslie models, such as the 51, do not contain amplifiers and must therefore be connected to an external amp. In addition, since CBS bought the Leslie company in 1965, several new models have been produced, including the 122A, 122XB, and 147A, as well as larger models made for multichannel organs. It is important when recording new or unusual Leslies to survey the construction carefully in case the unit employs a design change (a side-firing woofer, for example) that would affect sound production.

Tight Ship
Like a neglected drum set that squeaks and rattles each time it is struck, a rickety old Leslie can be a Pandora’s box of extraneous noise. Therefore, in addition to checking for any modifications, another important step is to listen carefully to the cabinet while the musician plays at full recording volume. (If the instrument is an organ, make sure the player uses the same drawbar settings that will be used during recording.) If you hear creaking, buzzing, or other unwanted noise—I specify “unwanted” because some of the resonances and distortions produced by a Leslie cabinet may be desirable—have the musician play chromatic scales slowly from lowest note to highest so you can pinpoint the note or notes that set off the noise. If you don’t hear the offending sound on single notes, try chords.

After determining which note or group of notes cause the noise, locate where the unwanted sound is coming from. The last Leslie I recorded had an obnoxious sympathetic buzz that I traced to some loose wood plies on the bottom-most panel. After discovering that I could stop the buzz with my hand, I put a piece of foam rubber on the spot and weighted it down with a 10-pound dumbbell. That didn’t completely stop the buzz, but it did damp it sufficiently for the recording.

Other common sources of noise are the Leslie’s motors, rotors, belts, and pulleys—any parts that move, basically. Hopefully, the player maintained those mechanical parts well. If not, you need to track down the noises and squelch them or move the microphones back from the source to minimize pickup of the unwanted sound.


Reprinted with permission from Magazine, March, 2001
2000, Intertec Publishing, A Primedia Company All Rights Reserved