October 11, 2013, by Daniel Abelson
I don’t typically write about products, mostly because I’m more interested in the human element in sound reinforcement.
To me, gear is the lesser part of the equation. Seventy percent of great sound is your contribution; the accumulated skill and experience of the show’s engineers and crew. Manufacturers create great tools for our industry, but I’m convinced that talented, experienced personnel using average gear will deliver consistently better results than average crews using the finest equipment available.
However, I do appreciate new gear when it makes the daily lives of engineers easier. Recently I was in Boston to review a performance of the Rolling Stones 50 and Counting tour, as the guest of Dave Natale, who has mixed the band since 1994 (Read about it here).
The evening before the show, Natale mentioned the Stones had been using a new device that simulates the sound of a rotating Leslie speaker on the Hammond B3 organ, and he stressed that it solved many problems and made the crew’s day easier.
Rising & Falling
Technically speaking, the Leslie speaker is not a reinforcing or amplifying device, it’s a sound enhancement device that uses Doppler shift to apply frequency modulation to the audio program coming from the instrument. This modulation adds a depth to the sound that, depending on the rotation speed of the horns, sounds floaty and dreamy when set at low speed or offers a rich bubbly vibrato at high speed.
The change of pitch occurs as the horn spins towards and then rotates quickly away from the listener. Physically it’s the same effect as the whistle on an approaching train, which rises in pitch as it nears and falls as it passes.
Most Leslie models feature a woofer that loads face down into a rotating drum, and a high frequency phenolic diaphragm compression driver mounted face up coupled to a rotating horn. Speed-switchable, belt-driven motors provide the rotation.
Although they share similar driver configurations, the balanced-in model 122 was typically paired with the B3, while the unbalanced model 147 was used by legions of guitarists in the 1960s and 70s to add depth and space to their signature sound.
Top and I/O panel views of the Ventilator. (click to enlarge)
As many of you likely well know, a Leslie presents challenges. For one, miking it can be a hassle, usually done with three mics on a pair of panned high channels and one low channel. In highly ambient environments, one often has to place the Leslie in an isolated spot offstage to control leakage.
Also, the belt-driven mechanics make noise, and the “wuh wuh” caused by rotating horns cutting through the air is particularly prominent if the speaker is tightly miked. There is a great variance of frequency response from cabinet to cabinet. Finally, most Leslies were made in the 1950s and 60s, and after decades of road use they often break down at inopportune moments.
Doppler effect is remarkably difficult to simulate. Many companies have attempted to provide an adequate Leslie substitute with varying degrees of believability. Clearly though, if someone successfully modeled that belt-driven Doppler-shifting tube-smacking dreamy Leslie sound in a stomp box, it would solve a lot of problems. Crews could be spared carrying, repairing, miking, and isolating an organ speaker whose technology hails from 60 years ago. It would make the lives of sound and backline crews much easier.
Fortunately, the smart designers at Neo Instruments of Germany have created the Ventilator. Chuck Leavell, the Rolling Stones keyboard player for 30 years, is responsible for elevating the profile of the Ventilator to a group of talented and seasoned audio professionals.
“I was introduced to the Ventilator by a very good Hammond technician in this part of the world named Greg Black (blackhammond.com),” Leavell explains to me. “One day he called and asked if I had heard about the Ventilator. My usual reaction, because I had tried every Leslie simulator over the years, was ‘yeah right.’ He assured me that this unit was special and encouraged me to listen to it. I tried it, was amazed, and thought to myself, ‘Is this as good as I think it is?’
“At the time I’d been working some with John Mayer, who works with a very talented engineer, Chad Franscoviak,” Leavell continues. “Chad just loved it and I have nothing but the highest respect for him. That really confirmed my thoughts about the Ventilator.”
For years Leavell has kept his Leslies in road cases that convert to iso booths, with mics permanently mounted inside the units. The obvious advantage of the Ventilator is elimination of the closed-in sound that happens with an iso booth situation, which still sounds like a Leslie in a box. The other problem the Ventilator solves is the wind noise (from the rotating horn and drum). There isn’t the need to use wind screens or to worry about mic placement.
“For those that may be wondering,” he adds, “I haven’t talked to anyone from Neo. I don’t have any kind of endorsement arrangement or anything, I don’t even know them. I bought the four units I own.”
When approached by Leavell about using the Ventilator with the Stones, Natale confirms that initially he wasn’t very excited about trying the box.
“You know I don’t like anything, so I don’t look for anything new because what works still works,” he states. “We were rehearsing in Paris, and when Chuck brought it in, I went ‘oh my what is this thing? Why do I have to try it?’ And then I thought ‘don’t be a jerk. He brought in this piece so let’s listen to it.’ So we set it up. Chuck played about two chords and I came running back in the room screaming ‘it’s amazing!’.”
According to the manufacturer, the Ventilator is a “digital FX device that simulates a Leslie model 122 rotary speaker cabinet miked up with a stereo pair for the highs and a single mono mic for the lows.” This configuration mirrors the mic setup used by most touring engineers I know. The folks at Neo have done a remarkable job of developing algorithms that recreate the rotating Doppler effect.
• Independent emulations of bass and treble rotors
• Reproduction of the Leslie’s mechanical properties
• Emulation of the 122’s frequency response
• Identical 800 Hz crossover point as found in the 122
• Adjustable rotary speed and acceleration
• Adjustable drive section that simulates distortion and power tube saturation typical of the Leslie’s amplifier
• Variable placement of virtual mics
• Relay-equipped true bypass circuit
• Port for a remote footswitch or organ-mounted “half moon” speed switch
• Full rotary stop
Natale states, “In this case I think it’s justified to tell people about this device because it gives you more consistency. It’s one less thing you have to worry about. What happens if the catering staff walks across upstage and knocks one of my mics off?
“You can adjust the drive without maybe blowing up the speakers in your Leslie like we used to do. You can control the acceleration, which I grant you is maybe a bit subtle of an effect for an arena with a million cubic feet of air, but it’s cool.
“I would always record with a Leslie. It’s a wooden box. It has a tone and a certain frequency response. But for live, now I don’t need a harness of three 100-foot mic cables to the edge of town to isolate the box. With the Ventilator, the unit is right next to all the keyboard DIs. It’s consistent. There’s no leakage. You should be able to deal with leakage if you’re a live engineer, but if the mics are in different positions from day to day it won’t be very consistent.
“Another great thing is there is no wind noise, that’s really great. (The Ventilator does model wind noise, and this is audible if you adjust the distance setting to the closest-to-the-cabinet position). I think it’s a really good product. Solid metal construction, small, weighs a lot less than a Leslie, no moving parts except knobs and switches.”
The Home Trial
I’m fortunate to own several vintage instruments, including a B3 and 122 and 147 Leslies. Even after glowing confirmation from two experienced engineers and a world-class musician, before writing this article I still wanted to do an A-B comparison of the Ventilator against the real thing in a listening environment I trusted.
So I set up a rotating “speaker” shoot-out in my music room, and in this setting, the Ventilator passed my 14-day home trial. Of course the B3 through the simulator did not sound exactly like my 122. I’m sure the Neo folks listened to a line-up of 122s before they selected the particular speaker they modeled. Considering the previously-mentioned variance in frequency response from one Leslie to another, no doubt the unit they modeled does not sound identical to the 122 I own.
Most importantly though, the Ventillator provided a realistic and legitimate alternative to the vintage device. The frequency response, timbre and overall instrument envelope were darn close, close enough that within a band’s ensemble mix I doubt a trained ear could consistently pick out one device from the other.
Composer musician Dr. Lonnie Smith, a true guru of the Hammond B3, working with a Ventilator.
I admit my tests were completely subjective – one listener, non-scientific. And I confess I wouldn’t choose to use it in an organ trio with jazz artists like Joey De Francesco, Ben Sidran, or the late great Jimmy Smith. In those settings, where the Hammond is the centerpiece of the program, the Leslie is probably the appropriate choice. But in many of the large venue presentations we support, including those with accomplished players like Leavell, practitioners of the live audio craft could recommend the Ventilator to their artists and reap the benefits of this well conceived and executed tool.
“I just love the thing, I really do,” Leavell tells me in parting. “As much of a vintage head as I am, whether it be a Wurlitzer or a Fender Rhodes or a Clavinet, it’s hard to find instruments that come that close to the real thing. But the Ventilator certainly does.”
Besides providing sonic legitimacy, the Ventilator doesn’t have any moving parts beyond pots and switches, only weighs a couple of pounds, takes no truck space, is not likely to break down, and you don’t have to mic it. It’s a very good substitute for a Leslie, and a problem-solving tool that could make your day easier.
Finally, for those who might wish to read the pre-eminent pro audio discussion of the Leslie speaker, I suggest Cliff Henricksen’s “Unearthing The Mysteries of the Leslie Cabinet.” Henricksen is a talented loudspeaker designer who grew up playing the Hammond in R&B bands.
After 40 years of playing with speakers, Danny Abelson is still infatuated with why things sound the way they sound. In his day job he is a consultant specializing in the electronic systems installed in college and professional sports facilities.
Editor’s Note: Neo has informed us that it is coming to market with two new mini Vent models, one for guitar and the other for organ. There will also be a new “pro” version in the coming months. Cabinet simulation for the Leslie 122 is included in all of them, of course, just like in the original.