Review: PSP L'otary

Detailed Plug-In Simulation of a Miked Leslie Cabinet
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Accurately emulating the iconic sound of a Leslie rotating speaker in software is no easy feat. Not only does the developer have to model the sound and characteristics of the amplifier in the Leslie, but it has to model the effect of two separate speaker elements that rotate independently at changeable speeds. PSP Audioware took on the challenge and the result is PSP L’otary ($99), a plug-in that not only simulates a Leslie, but also re-creates how it sounds through a variety of miking configurations.

The plug-in runs in 32- or 64-bit mode on Mac and Windows and supports RTAS, VST, AAX, and Audio Units.

PSP L’otary is based on two classic Leslies, the 122 and 147. The GUI is split into three sections, with controls for the high-frequency Horn on top and the low-frequency Drum on the bottom. Controls are arranged in color-coded groups, so that it’s easy to tell which knobs go with each function. The center section contains global controls, including an EQ with fixed Bottom, Low-Mid, Presence, and Top bands. Each band can be cut or boosted by 12 dB. The Mech knob adds sampled noise from both motors, as well as turbulence caused by the horns—useful if you’re going for absolute authenticity of the Leslie experience.

Setup lets you select one of five mic-placement configurations (utilizing a stereo pair for the horn and one on the drum), based on standard Leslie miking schemes. An additional setting called Amp gives you a simulated DI feed from the Leslie’s amplifier, bypassing all the spinning parts.

The Amplifier section features Input Level, Type (Tube, Solid [-state], and Thru), and Drive controls, allowing you to dial in overdrive and gain boost. The Ambience section controls the size and characteristics of the room where the Leslie is situated.

Horn and Drum sections each include Fast and Slow parameter knobs, which set the upper and lower limits of their spin speeds. Control the Horn and Drum together with the Speed Lever, a continuous control that goes from slow (Chorale) to fast (Tremolo), and anywhere in between. The speed of that transition is controlled by the Inertia knobs: Set them to change instantly when the Lever is moved to a different setting, or slowly ramp up or down. Speed, Inertia, and all of L’otary’s parameters can be automated. Further options for sound shaping include controls for mic distance, preamp gain, and filtering (highpass on the Horn; lowpass on the Drum).

A Low CPU mode can be turned on in place of the higher-quality Brilliant mode. There are 16 presets, including a 147 and a 122 patch, and includes room for 15 more settings. I was a bit disappointed with the presets, which were too few and not very inspiring.

I compared PSP L’otary with the rotating speaker sections of several organ instruments. I’d listen to the complete internal sound, and then turn off the rotating speaker effect and insert PSP L’otary instead. Without fail, PSP L’otary sounded more realistic. It wasn’t always as pleasing as the instrument’s Leslie simulation—although it often sounded better—but it always sounded more like the real thing.

I also found the plug-in useful for processing guitars, vocals, synths, sampled electric pianos, and more. PSP L’otary is definitely the most authentic Leslie simulation I’ve ever heard.

Realistic Leslie behavior and sound. Mic choices. Tube and solid-state overdrive. Ability to alter room size. Four-band EQ. Reasonably priced.

Preset selection is small and uninspired.


Mike Levine is a musician, composer, and producer from the New York area.