Review Roundup: Rotary Speaker Simulator Pedals

A buying guide to rotary speaker simulator pedals
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When it comes to killer organ sound, the rotary speaker is more than half the battle. A real Leslie or good simulation will make even a static organ bank from an old ROMpler sound credible; a bad simulation will make a great sound cheesy. The same is true of the vintage Hammond B-3 and its siblings, which didn’t achieve legend status until paired with Don Leslie’s invention. Luckily, the quality of the emulation that can now be packed into a stompbox is largely stellar. In this roundup, we’ll break down the features you need to know about, then survey the current product landscape.

Do You Need a Rotary Pedal?

If you have a recent portable drawbar organ and you’re happy with its onboard rotary effect, the simple answer is no. If you have an older one—early Nord Electro, Roland VK series, Hammond XB2 or XK2, etc.—adding a current rotary sim is a monumental sonic upgrade that is a lot cheaper than replacing the whole instrument.

Likewise, we’ve never met a workstation or stage combo keyboard whose organ patches or mode couldn’t be improved by an outboard rotary simulation. Many keyboards, such as the Korg Kronos, Kurzweil PC3 and Forte, and Yamaha Motif series let you set up multis with sounds of your choosing routed to alternate outputs. This lets you pass organs through a rotary pedal but send pianos and everything else to the main P.A., which is a great solution for taking just one keyboard to the gig.

Simulations should also not be dismissed as alternatives to the real thing. Unlike vintage tube models, current solid-state Leslies such as the 3300 are loud enough to stand tall in a guitar-heavy rock band, but car space, stage space, setup time, and available mixer channels for miking can make bringing one impractical. A parallel case for recording is that since what you hear in the final product is a miked-and-panned Leslie through stereo speakers anyway, a good simulator saves time and hassle—and may be the only option if your home studio is short on mics.

A Quick Leslie Primer

No speakers actually move inside a Leslie cabinet. A stationary woofer and tweeter, crossed over at 800 Hz, are mounted with the woofer firing downwards into a rotating drum-shaped baffle and the tweeter firing up into a rotating horn. Only one side of the treble horn passes sound; the other is blocked and serves as a counterbalance. Many early Leslies only ran at what we now call fast speed—given Don Leslie’s original quest to create the tremolo and ambience of a theater pipe organ—but of course also having the slow “chorale” speed is the standard. A sometimes overlooked detail is that the horn and drum spin in opposite directions.

The unobstructed bass and treble “windows” are thus swinging around at you once per rotation, which creates the signature sound. It’s a complex cocktail of simple ingredients: Vibrato (pitch modulation) created by the Doppler effect; tremolo (amplitude modulation); these two things also happening to any sound bouncing off the walls; and, depending on the room, a bit of phase shifting from the interaction of direct and reflected sound.


What makes for a good simulation? First of all, there are two standards of comparison. One is having a real Leslie (likely a 122 or 147) next to you and playing—or listening in an intimate enough club that you’re hearing the Leslie directly. The other is the sound of a miked Leslie as heard on your favorite recordings or through the P.A. at a larger venue. The second is easier to achieve, but some of the pedals in this roundup get closer to the first than ever before. Listening in stereo, or even in mono if you monitor through a single powered floor speaker, you should be convinced of two distinct motions for the bass and treble frequencies. The vibrato shouldn’t overpower the tremolo, nor vice versa. The effect shouldn’t rely on phasing—if it sounds like a phaser, as you might use on a Rhodes sound, it’s too much—nor on exaggerated stereo panning. Most importantly, there should be a sense that the sound is circulating around a central point as opposed to just oscillating “in and out” of the speaker(s).

A word about stereo: All the pedals in this roundup have stereo outputs and create a stereo signal from a monaural one. But what about stereo inputs? They’re nice but not strictly necessary. Unlike piano, orchestral, or synth sounds, which can and do benefit from sampling, the signal a vintage B-3 sent to a vintage Leslie was monaural. Sure, your modern organ or “clone” has stereo outs, but they’re mainly there for the benefit of the built-in rotary simulation, plus whatever nonorgan sounds the thing makes. Switch those off, and at the level of raw tone generation, all the same frequency information should be in both channels. Stereo-izing is just part of the magic of a good rotary simulation—and again, shouldn’t be leaned on too heavily. So while you should take the pedal’s output in stereo if your house P.A. supports it, running into the pedal in mono is fine.

A tip for your own listening tests: Just about any simulation can get a great Jimmy Smith sound or similar (e.g., lower drawbars and slow speed). High frequencies are more directional, and what happens to them at fast speeds is harder to replicate. So pull the 16', 8', and the top two or three drawbars and hit the gas. This frequency spread will also help you listen for the differences between the two virtual rotors.

The Lineup

With the help of San Francisco Bay Area organists Brian Ho and Wil Blades as well as Keyboard editor at large Stephen Fortner, we studio-and gigtested five pedals—the Electro-Harmonix Lester K, GSi Burn, Hammond “Cream” Digital Leslie Pedal, Neo Instruments Ventilator II, and Pigtronix Rototron. The instrument sources, which had their internal rotary effects bypassed, included a Hammond XK-3C as well as a vintage A-100, a Studiologic Numa Organ, the KB3 mode on a Kurzweil K2661, some sampled organ sounds from a Yamaha Motif ES, and a Roland VK7.


Lester K

$179 street;

After decades of releasing innovative effects pedals, EHX has major credibility. We last encountered their B9 and C9 Organ Machine pedals, which are designed to make a guitar sound like an organ. Although the rotary effect is one of many interesting sonic affectations for a guitarist (think Stevie Ray Vaughan or Pink Floyd), it’s an essential for keyboardists. And we’re way pickier about it. Can EHX bring it?

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If you’re looking to improve the sound of an older “clone” or sample set and keep the expense to a minimum, the answer is a resounding yes. Stephen Fortner was surprised and delighted at what it did for VK7, older Kurzweil KB3, and Motif sounds. “You can certainly hear both virtual rotors going,” he observed. “Spin-wise it reminds me a lot of the internal sim on the Studiologic Numa, but on side-by-side listening, the latter has a pronounced chorus effect you can never quite separate out. Which is to say the Lester K may be more technically correct.”

The controls are simple—input volume, drive, separate pots for slow and fast speed (but no control over transition rates between the two), and upper/lower rotor balance. You can make the slow and fast speeds both inauthentically so—about 10 o’clock for slow and 1 o’clock for fast got closest to the Leslie 142 that was powered up at the time. Drive is nice and warm, and though it doesn’t go all the way to Jon Lord levels of distortion, it also doesn’t get too obviously buzzy when pushed hard; EHX’s experience in the guitar space is of obvious benefit here.

Footswitch operation gives positive feedback, although it lacks that stiff click you’d feel on many stompboxes; whether you like this or not is a matter of personal preference. Furthermore the bypass is buffered—a useful carry-over from the guitar world.

EHX also sent us their Lester G model, which includes all the features of the Lester K but has a mono Hi-Z input for guitarists (the K has stereo ins) and adds an expression pedal input, a compressor with variable attack and sustain, and, ironically, an acceleration/deceleration control, which the K lacks.

The Lester K is the most affordable pedal in this roundup by a wide margin. One trade-off is that it has more of a noise floor than the more expensive pedals, but perhaps not more so than a vintage Leslie. A larger trade-off is in the realism of those tricky high drawbar frequencies at fast speed: This is where the Lester K starts to sound electronic. But it’s still better than the internal simulations from most organs and workstations of, say, ten or more years ago. Which is to say, it can add a lot of oomph to a lot of still-gigged-on instruments for not a lot of money.



$449 street;

GSi (Genuine Soundware) is the Italian developer that brought us such instrument plug-ins as VB3 (organ), Mr. Ray (Rhodes), and Mr. Tramp (Wurly), and they share chief engineer Guido Scognamiglio with the reborn organ clone maker Crumar. Burn throws everything they have at rotary simulation, and operationally, it comes off more like a studio effect that happens to be in a pedal instead of a rack. It’s the only unit here with memory presets, menus, and all parameters addressable via MIDI. Those parameters are extensive, offering customization of the sound on par with what you’d find in a Hammond XK-3C or SK-series organ.

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This includes gain for the real tube overdrive, woofer and tweeter volumes, separate fast and slow motor speeds for the treble and bass rotors (expressed in Hertz), separate rise and fall transition times for each rotor, three values for the amount of pitch modulation involved in the rotary effect, three values for the bass-treble crossover point, and various settings for horn resonance and timbre, which an experienced rotary buff could use to get closer to different years and models of cabinets and whether the plastic diffusers are still on the treble horn or have been removed as some Leslie owners used to do.

Onboard reverb options are also available in abundance. The first setting encountered upon pressing Edit, though, is an overall effect type that covers a huge variety of cabinet models and miking schemes as well as several non-rotary effects such as phaser, ping-pong delay, and a Step Filter that seems intended for copping the intro to the Who’s “Won’t Get Fooled Again.” (The usefulness of this in a live band is undermined by the fact that Burn doesn’t support MIDI tempo sync nor tap tempo.)

Although poking around the two-line LCD to edit all the settings can get tedious—especially in how it requires jockeying between the Edit and Exit buttons to navigate menu levels—a free software editor/librarian (Mac/Win) puts everything right in your face.

A TRS remote jack is for a speed footswitch or half-moon lever; you can also add an optional adaptor cable that puts a MIDI port on the other end, letting you control run/stop and speed with CC messages (using a mod wheel or the speed buttons for your keyboard’s internal sim) while leaving the other MIDI port open for other applications such as firmware updates and talking to the software editor. There’s no USB port, though, which would make both those tasks easier in today’s world.

How well does this highly programmable “rotary construction kit” do the core job of realism on organ sounds? With high honors. Brian Ho thought it had a “slightly more ballsy, strident, and hyped tone” than the Ventilator II. Stephen Fortner praised the overdrive: “It tends to break up gradually and naturally the way a tube Leslie does. Overdrive effects on some organs, by contrast, can sound like you’re cross-fading in a distorted signal.” Of the all-important sense of rotation, he said, “Over a wide range of presets, there’s a nice throaty warble that’s not relying excessively on vibrato. There’s almost this vintage ballpark or roller rink quality to it, though I noticed that compared to other pedals, it sounded much better in stereo than in mono.”


“Cream” Digital Leslie Pedal

$399 street;

Parent company Suzuki has owned the Hammond and Leslie brands since 1985, and while some players have preferred their competitors over the years, their current generation of products is so good that that will change. Hammond’s flagship stand-alone rotary pedal is no exception. Originally simply called the Digital Leslie, the nickname “Cream” now distinguishes it from two recent and more compact offshoots—the Leslie K and G pedals, respectively intended for keyboards and guitar.

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The cabinet selector offers four options: 122A, 147A, the 18V single-rotor “Vibratone” preferred by blues guitarist Stevie Ray Vaughan, and finally the Hammond PR40 tone cabinet, which doesn’t rotate but sounds sweet and opens a historical window into how founder Laurens Hammond would have preferred you hear the organ. Though the fast and slow speeds themselves are factory-set according to Hammond’s measurements of ideal vintage models, they share a common rise/fall knob for the rotors’ transition times when switched.

Hammond’s own website says the sim is derived from their SK keyboards, but the latest firmware updates convinced us it’s more realistic. The 122 and 147 cabinet models in particular, according to Fortner, have “spot-on frequency responses and rotational speeds compared to the real things, and I’ve owned both.” Ho observed that the Cream “really opened up when connected to a real [vintage] organ,” and agreed that it “sounded better than the SK sim.” The sound swirls around convincingly, and the effect sounds good in mono—an important consideration since the sound systems in many venues are wired that way.

The Cream’s overdrive is the subtlest of the lot, adding a level boost and some grunge but nothing close to driving-your-Leslie-with-a-Marshall type distortion. That subtlety is also found across the full knob sweeps of the other settings: Hammond seems to be going for the purest, most “stock” listening experience—that first of two standards we discussed in the introduction—as opposed to playing back our memories of how a Leslie’s character was exaggerated by this or that recording technique. (As one Hammond rep quipped, “We’re not in the caricature business.”) If there is a trade-off here, it’s that if you want more drama—an accentuated Doppler effect or the “motorboat” tremolo that results from miking the bass rotor on-axis—you may find that the available settings don’t push the extremes you’re after.

One possible inconvenience: Despite having enough room on the chassis for dual inputs, the Cream places stereo on a single TRS jack. So to run both your keyboard’s outputs in, make sure you keep a Y-cable handy.

All in all, the Hammond Cream pedal is an excellent choice for those who are after a highly accurate rendition of playing a clean, stock Leslie 122 or 147 that’s fresh from the store. For this purpose, it gives you all the settings you need and none that you don’t, contributing to ease of use. Its sound and build quality also prove that today’s Hammond company has not just a legal right to the Leslie name, but a common-sense one as well.

Though the Leslie K wasn’t available in time for this roundup, Hammond did lend us a G. It features the same cabinet models (except for the PR40), audio ins and outs, a Red Line knob to set maximum tremolo speed, and separate dry and wet mix knobs. Since it’s focused on guitar but can be used with keyboards, we’ll cover it in more depth when this article goes online.)


Ventilator II


Even though the Ventilator II was favorably reviewed in our December 2014 issue (as was the first-generation model in 2010), it owns so many hearts and minds among keyboardists that no rotary roundup would be complete without it. We’ll start by recapping the basic controls.

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The unit’s tank-like construction houses five knobs in a recessed channel, with each knob performing two functions; you get to the secondary page of functions by holding the Bypass and Slow/Fast buttons at once. (As on the Lester K, these are the “solid but not clicky” type.) The first knob shares overall fast and slow speed control; the second, rotor balance and rise/fall time; the third, overdrive and cabinet emulation mode; the fourth splits the mic distance of the low rotor with how a connected remote speed switch works; the fifth, high rotor mic distance and overall level. A unique feature is that by dialing the low mic distance (not speed) to zero, you can get the “Memphis sound” of a stationary bass rotor without removing any low-end content from the sound.

Though this approach offers more parameters than the Hammond pedal and requires far less menu-diving than the Burn, it can still be inconvenient. For example, while playing you may want to tweak fast and slow “speed limits” at the same time, but these two are on one knob and a Shift operation is needed. Then again, with any of these pedals, most organists are likely to set it to the one sound they prefer.

About that sound: Many players consider the Ventilator II a unicorn among rotary pedals. To Brian’s ears, it had “a great sense of 3-D compared to the other pedals” and a “nice and creamy overdrive,” and was also his favorite simulator in mono for “those quick, one-speaker, in-and-out gigs.” While Fortner thought that that the Hammond Cream was “more like a Leslie 122 or 147 up close,” Brian said the Ventilator II was “more like a 122 in a room.”

With the benefit of the Hammond pedal being around (which we didn’t have in 2014), Fortner continued, “There’s no question that if you play through the Ventilator II cold, it sounds stellar, with a great sense of moving spatial location and moving air. But after a lot of A/B’ing with the Cream, the two seem to be philosophical opposites. Where the Hammond sounds very stock, the Ventilator II sounds more like a modified Leslie miked in a reflective room. Analogous settings on the Vent can get more extreme on either end, though the Burn still takes the cake if you want to go way outside.” That’s not to say there’s intentional room simulation or reverb being added; there isn’t.

As similar as the settings could be made, the Ventilator II had a more pronounced Doppler effect than either the Burn or the Cream, and subtly more phasing (unless of course you turned on the Burn’s actual phaser). Though playing or recording through the Ventilator II will certainly get you compliments on rotary sound, it’s inherently more dramatic than its Hammond counterpart, which will be more to some players’ tastes than others.




The Pigtronix Rototron has the distinction of using all analog circuitry to generate its effect, which makes it unique. Full stereo throughput is complemented by TRS control jacks for both the high and low rotors, which means you can employ two expression pedals for continuously variable control over bass and treble rotation speeds, independently.

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Slow and fast speeds are separately adjustable (speed switching via the usual stompbutton shares a common rise/fall time). The most dramatic control over the sound, though, is via the Depth knob. Fully counterclockwise, you get a shallow vibrato-chorus effect reminiscent of setting C1 on a vintage Hammond as heard through a stationary tone cabinet. All the way clockwise, you get exaggerated Doppler and deep tremolo that sounds as if both rotors of a speaker were recorded on-axis through very directional mics and, if you listen in stereo, panned hard. The best settings for an ideal Leslie sound put both the Fast Speed and Depth Knobs at 1 o’clock.

The Pigtronix website claims that its analog-only design “sounds warmer, fatter, and feels far more realistic that the digital rotary effects currently available from other companies.” We’ll go with warmer and maybe even fatter, as the analog factor definitely lends something that is very immediate and present. High frequencies in particular come across very smoothly and the fast speed imparts a very pleasing shimmer. We could see reaching for this to modulate a Rhodes, Wurly, Clav, or even synth—either because the patch sounds a bit too digital or because the Rototron’s take on modulation is so smooth and creamy. It’s also super clean and quiet.

But realistic on organ? We can’t see it being an upgrade from the internal simulations on the various clones we had around, with the possible exception of the Roland VK7. Fortner did offer one counterpoint: “This reminds me, more than a little, of a rotary simulator that was also analog and was the most-wanted model of its time—the Dynacord CLS-222. Call up some YouTube videos of that—which actually sound quite good—and you’ll see what I mean.”

It should also be said that the Rototron definitely sounds cooler than what usually happens when you turn up the mod wheel on a general-purpose workstation or ROMpler’s organ patches. We’d recommend it most to an analog enthusiast who wants to add a unique modulation tool to their keyboard rig.