Back in the 40s, only a few manufacturers tried making these types of cabinets to emulate a pulse or vibrato effect on instruments such as organs, guitars, and keyboards, and can use this effect with a live performance or a studio recording.
Many decades later, this technology has become lighter, smaller, and cheaper, where you can now find them as a more standalone version instead of a large cabinet.
But how do all the parts work together in these newer models, and does this differ much from the technology that was used back in the 70s?
In this article, we take a closer look at this technology and see the things you can do with the technology and the various forms you find it in.
Read on to find out more about this interesting piece of emulation kit.
Overview Of A Rotor Cabinet
Before we look into how the system works, it’s a good idea to know what all the parts are to see how it functions on an individual level, and perhaps your current system shares some of these parts.
At the top, you’ll see a molded ABS horn that projects the frequency, a custom-made 15” woofer that helps with low frequencies, an A.C motor with low-noise ball bearings, and a hand-crafted all-tube amplifier that is designed for Leslie models of this cabinet.
You can also find a high-power, solid-state amplifier and molded foam drum that sits just beneath the woofer and acts as a cover for the output, so it works at whatever speed you set it to.
If we’re talking about Inputs, you can find that these models have an 11-pin Leslie connector, and some have a ¼” line input jack and footswitch jack.
You’ll find these cabinets have a master volume control and a power on/off switch, and for other instruments, you can get these cabinets custom-made to meet your requirements.
For example, you might like the vintage look of the interface panel and request that it be put in, or if it means you have a better time using it if you’re not a fan of the new Leslie systems.
How Does A Rotor Cabinet Work?
If you see videos of this cabinet working, you’ll notice that it spins, and this isn’t just for looks and has an interesting function.
This spinning results in a pitch modulation by exploiting the Doppler effect, producing either a pulse or a unique vibrato.
If we use it as an organ cabinet, a model allows its sound deflectors to rotate at the speeds of chorale or tremolo.
What makes this equipment interesting is the impressive sound that is produced during rotation, which is known as rise or fall.
With the use of the two sound deflectors, one for bass frequencies and the other for high frequencies, you’ll notice that effects are created when changing the speeds.
This is since the bass rotor always accelerates and decelerates more slowly than the high-frequency horn.
If you listen to an organ being played that has one of these cabinets hooked up, you will notice the frequency rise and fall as various keys are played.
What Is It Like Using A Leslie Speaker?
If you have an old-style cabinet, you’ll find it’s as easy as switching it on and letting it do this work, but if you’re using an organ, you’ll have to ensure that the wiring is compatible with the organ’s input, which might be an issue if you have a newer model.
You could add a second cabinet to your setup, but this might be more effective for those doing a live performance or recording, where they want to enhance the sound even more.
What’s even better is that in modern times, manufacturers have been able to make these speakers into rotary speaker effect pedals that have a simple design that you can easily toggle the speeds and can be adjusted independently.
These newer systems emulate the classic speaker and have one mic for the bass and two for the treble rotor or the horn that we looked at earlier.
Is There Software That Can Emulate This Effect?
We’re glad to say that, yes, there is the potential to use this effect on software such as logic pro, provided by Apple, and you have various options from the motor controls to the microphone type, so there’s a lot to experiment with here.
There are multiple parameters, such as the cabinet type drop-down menu, the type of sound you want to emulate by model, a single motor, a split of the bass router signal, and impulse responses that can direct the signal.
You can have it routed slightly to the left and have the treble rotor signal go more to the right to get a more balanced sound that works with any type of audio from any instrument.
You could also add effects, edit, mix, or add loops to your projects that can take your recording to the next level and is great for those who want to emulate a particular sound.
As long as you have a good grip on this software, it can be used by pretty much anyone.
I often add a rotor cabinet to my drones or long cello notes to give it more movement and make it sound more interesting.
Frequently Asked Questions
Should I Use A Leslie Speaker?
Considering that this speaker can enhance many instruments and even vocal outputs, you might want to reserve these devices for live performances, as it can be difficult to hear the richness from a recording or through a sound system.
However, if you’re in a professional recording environment, you can use up to 3 or 4 microphones to record the outputs on the speaker.
Getting that classic Leslie sound might take some adjustment with the microphones, so it depends on how knowledgeable you or a sound engineer are with this style of recording, and consider using software that could make this process easier for you.
The great thing about using a virtual Leslie is that you can replicate the sounds from the classic B3 or C3 models, with the option to use later models that can give you a variation of the Leslie sound.
There are many ways that you can tweak and restrict the effects of the rotating parts, so it might be worth experimenting with it to see if this method is one that improves your recordings.
How Do I Choose A Rotary Speaker Effect Pedal?
You might have seen many variations of this pedal, some that look a bit more complicated than others, and the best thing to do here starts with a simple design that allows you to change the rotor speed, and you can control the proximity effect and the top end frequencies.
You can then look at more robust designs that use an overdrive to mimic the warm distortion of the Leslie cabinet.
This might take some experimentation on your part, but you can practice until you get the sound that you’re looking for.